(Lutjanus malabaricus) to re-instill eafood Council

Transcription

Management of 'tough fish syndrome'
in tropical Saddletail snapper
(Lutjanus malabaricus) to re-instill
market confidence.
Andrew Forrest, Sue Poole, Paul Exley,
John Mayze, and Carl Paulo
Queensland Government
NORTHERN
TERRITORY
eafood Council
WORKING TODAY FOR A SUSTAINABLE TOMORROW
Australian Government
Fisheries Research and
Development Corporation
Project
2010/207
Manag e m e nt of tough fish synd rom e
Management of 'tough fish syndrome'
in tropical Saddletail snapper
(Lutjanus malabaricus) to re-instill
market confidence
Andrew Forrest, Sue Poole, Paul Exley,
John Mayze, and Carl Paulo
Project
2010/207
August 2012
Forrest and Poole (20 1 2)
iii
Management of tou g h fish syndrom e
ISB N : (978-0-7345-0428-9)
Management of 'toug h fish synd rome'
malabaricus) to re- i n st i l l market confidence
in
tropical
Sadd l etail
snapper
(Lutjanus
Andrew Forrest, Sue Poo l e , Paul Exley, John Mayze , and Carl Paulo.
Final report of project number 2 0 1 0/207 submitted to the Fisheries Research and
Development Corpo ration in August 2 0 1 2.
Copyright Fisheries Research and Deve lopment Corpo ration
Agricultu re , Fisheries and Forestry, Queensland . 20 1 2.
and
Department
of
Th i s work is copyrig ht. Except as permitted under the Copyright Act 1 968 (Cth) , no part of
this publication may be reproduced by any process, electronic or otherwise, without the
specific written permission of the copyright owners. Information may not be sto red
electronical l y in any form whatsoever without such permission .
Disclaimer
The auth ors do not warrant that the i nformation i n this document is free from errors or
omissions. The authors do not accept any form of liabil ity, be it contractual , tortious, or
otherwis e , for the conte nts of this d ocument o r for any consequences ari sing from its use
or any reliance placed upon it. The informat i o n , opinions and advice contained i n this
docume nt may not relate , or be relevant , to a reader's particular ci rcumstance. Opi n io n s
expressed by t h e authors are t h e ind ividual opi n i o n s expressed b y those persons and are
not n ecessarily those of the publisher, research provider or the FR DC.
The Fish eries Research and Development Corporati on plans, i nvests in and manages
fisheries research and development through out Australia. It i s a statutory authority within
the portfolio of the federal M i nister for Agriculture , Fisheries and Forestry, jointly funded by
the Austral ian Government and the fishing industry.
Information i n this report is provided as general advice only.
For app l i cation to specific circumstances, professional advice should be soug ht.
The D e partment of Agriculture , Fisheries and Forestry, Queensland, has take n all
reaso nable steps to ensure that the i nformation contai ned in this publication is accurate at
the time of pub l icatio n . Readers should e n sure they make appropriate i nquiries to
determ i n e whether n ew i nformation is available on the particular subject matter
The Fish eries Research and Development Corporatio n plans, i nvests i n and manages
fisheries research and developme nt th roughout Austral ia. It i s a statutory authority within
the portfolio of the federal M i n ister for Agriculture , Fisheries and Forestry, j o i ntly funded by
the Austral ian Government and the fishing i ndustry.
For enquiries or further copies of this report, contact
Innovative Food Tech nologies
Crop and Food Scie nce
Department of Ag riculture , Fisheries and Forestry
39 Kesse ls Road
COOPERS PLAI N S QLD 4108 AUSTRAL I A
Or
Fisheries Research and Developme nt Corporation
P.O. Box 222
DEAKIN WEST ACT 2600 AUSTRAL IA
iv
Manag e m e nt of tou g h fish syndro m e
Acknowledgements
Many thanks to the stakeholders of the Northern Finfish Fishery for su pplyi ng of
fish at their own cost, without which this work could not be possible. Particular
thanks to o u r industry partners who contri buted financially, namely Bi l l Passey
(Australia Bay Seafoods), Horst Fisher (Northern Seafoods) , Steve Hinge
(Goldband Nom inees Pty Ltd) and David Caracci olo (NT Fish Pty Ltd ) .
Thanks also t h e skippers of the vessels that participated in this project. I n
particular, Grant Nicolias, skipper of F V Starlight f o r g iving m e space on his
vessel to perform our experim e nts, and taking the time to expl ain the ins and outs
of the fishery g round and the fishing m ethods employed . And to Raymond
Passey of FV Territory Leader for providing so much time and effort with h is crew
to e nable the authors to complete this project.
Many thanks also to An i ta Sykes and Janet Stark of CSI RO Food Science for
com pletion of sarcomere analysis.
A ve ry special thank you to Katherine Sarneckis, Chief Executive Officer of the
Northern Territory Seafood Cou ncil for her ti reless support and strict ad herence to
timelines .
T h e authors wou ld also l ike t o acknowledge the su pport a n d f u n d i n g contribution
of the Fisheries Research and Develop ment Corpo rat i o n without wh ich this
research wou ld not be possible.
v
2010/207
Management of tough fish synd rome in tropical Saddletail
snapper (Lutjanus malabaricus) to re-instil l market confidence.
P R I NCI PAL I N VESTI GATO R:
AD D R ESS:
Sue Poole
I n novative Food Tech nologies
Departm ent of Agricu lt u re , Fisheries
Forestry
1 9 Hercu l es Street
Ham ilton OLD 4007
Tel : 07 3406 8689 Fax : 07 3406 8698
and
O BJECTIVES:
1 . To identify any post-capt u re practices that m ay i nf l uence the occu rrence of
tou g h fish syndro m e (TFS ) .
2. To identify l i n ks between TFS and specific phys iological factors i n tropical
Sadd l etai l snapper
3 . T o establish variability o f TFS i n relation t o season a n d captu re location
4. To develop recomm endations and st rateg i es for i ndustry stake holders to
m i n i m ise the i m pact of TFS
5. To com m u n icate findings and reco m m e ndations to stakeholders and assist
with the implementation of any changes to cu rrent fis h i n g and hand l i ng
practices
vi
NON-TECHN I CAL SU MMARY
OUTCOMES ACH I EV E D TO DATE
A major ach ievement of this research is the confirmation of fish age being the
prim ary d river of tough n ess i n cooked Saddletai l snapper fles h . Knowing the
cause provides confidence to develop solutions and m ake business decisions for
the reef fish fisheries.
The influence of other fish physiolog ical factors was shown to have little im pact
with respect to fish flesh tou g h ness. Add itionally, there was no apparent
con nection betwee n flesh toug h n ess and seasonal ity nor year to year co nditions.
The poss ibil ity of tou g h n ess being engendered throu g h inappropriate ch i l l i ng
imm ediately post captu re was ruled out as a facto r contri buti ng to toug h fish
syndro m e (TFS) .
The outco m e following on from identification of the cause of TFS su rrou nded
developing procedu res for reducing the i ncidence of tough fish where the cause
was preventable. Howeve r, as post-harvest hand l i n g was not a contributor to
tou g h n ess, im plementing alternative handling procedu res was irrelevant.
The focus of this outcome s hifted to developing strateg ies to ensure fish at risk of
exh ibiting TFS did not enter the value chai n . Th is was add ressed by provision of
currently available tech nology on non-i nvasive u ltrasonic i m ag ing and near i nfra
red spectroscopy ( N I RS) to the i ndustry partners. Add itional ly, the authors
proposed several alternative approaches to address m i n i m ising the i m pact of TFS.
Each approach was considered f u l ly with industry at a special stakeholder m eeting
( November 20 1 1 ) and options reduced to the two most favou red by the key
mem bers .
Due t o t h e obvious passion and comm itm ent from industry towards resolving the
TFS iss u e , and although beyond the scope of the project as stands, add itional
work was undertaken : an assessm ent of consumer perceptions of tough ness in
cooked Saddletai l flesh and 'proof-of-concept' trials with enzym e treatment of
tou g h f i l l ets .
The cu rrent project was able to establish an accu rate incidence of TFS in
Saddletai l snapper and was des igned to su bstantiate the perceived correlation
between fish age and flesh tou g h n ess, as we l l as assess the influence of other
l i n ked factors . A total of 504 Saddletail snapper, caught over 4 years from
northern Australian waters , were subjected to flesh textu re analysis. Of the total,
the m ajority (71 %) demonstrated a textural firm ness i n the range of 40-60
m i l l ijoules/gram (mJ/g) req u i red to shear the fles h .
As previously reported the prim ary d river o f tou g h n ess i n cooked Saddletail
snapper flesh appeared to be age of fish. Work i n this cu rrent project confi rm ed
this i nference, with resu lts demonstrating a h i g h ly significant correlation between
fish age and flesh firmness. The previous work identified a pote ntial seasonal
influence for toug h n ess. Additional data collected d u ring this work allowed
analysis four years of seasonal informati o n . Analysis of the g reater sample
popu lation demonstrated influence of seasonal effects was not s i g n ificant over the
fou r years exam i n ed .
T h e influence o f sex, size a n d weight o f fish was assessed with respect t o cooked
flesh texture. It was established that although male fish are sign ificantly larger
vii
Management of toug h fish syndrom e
than female fish of equ ivalent age , no d ifferences exist between t h e cooked flesh
textu res of fish of equ ivalent age. Stress is often attributed as affecting the textu ral
quality of fish flesh and a ready m easu re of the stress experienced is final p H .
Resu lts showed differences i n m ean fi nal pH val u es i n fish were h i g h ly s i g n ificant,
however there is no obvious relationship con necting pH to cooked flesh
tou g h ness.
Cold shock syndro m e can occu r i n tropical fish when their temperatu re is reduced
abru ptly from ambient and resu lts in phys ical stiffen i n g characteristics s i m i lar to
rapid o nset of rigor mortis. To establish whether this effect was influencing
tough ness of flesh from Saddletai l snapper, trials were u ndertaken at different
ch i l l i n g rates i m m ediately post-captu re of fis h . No s i g nificant differences i n the rate
of rigor mortis development were observed between three chilling temperatu res.
However, a clear pattern i n the developm ent of rigor was i l l u strated from the m ean
rigor values of fish from each ch i l l i ng m ethod. Fish su bjected to the coldest ch i l l i ng
med i u m (ice s l urry) showed a faster rate of rigor developm ent than fish held at
warm er tem peratu res. Fish rem ai n i n g at am bient h ad delayed onset of rigor with
su bsequent slower deve lopment.
Our work has i l l u strated no cold shock i n Saddletail when subj ected to a sudden
and large temperatu re differential beyond the normal rigor mortis developm e nt
process. Nor was there any d iffe re nce i n sarcomere length observed betwee n fish
ch i l led at different rates. Both these findi ngs su pport the concl usion that
toug h ness i n Saddletai l snapper is not d irectly cau sed by the fish expe riencing
cold-shock syndro m e .
Consumer perceptions o f tough ness
Texture analyses i ndicated and range of cooked flesh qual ity with respect to
deg ree of toug h n ess. It became critical to u nderstand the consumer perception of
tough ness and ' how tough is too toug h ' . This is i nformation is requ i red to establish
at what level Saddletail snapper beco m es u n acceptable to the consum ing public
and therefore, what proportion of the catch is affected .
Resu lts from a threshold of rejection consumer assessment showed a clear trend
of reducing acceptability with i ncrease i n toug hness. When this tou g h n ess l evel is
applied to data collected from all Saddletai l snapper over fou r years, 1 1 . 6% of all
fish exceed this valu e of 72mJ/g i n f i rm ness. When the perceived toug h ness is
reduced to 60mJ/g , the proportion of the catch exceeding that l evel increases to
25%. This i l l u strates that 1 in 4 wit h i n the catch m ay be perceived negatively at
the consum e r plate. Based on 2009-20 1 0 fishery data such a proportion equates
to $ 1 3 M reve n u e .
Strategies to mini m i se TFS i m pact i n t h e marketplace
No sim ple assessm ent m ethod is available for on-board use to m easu re a
parameter that will predict the flesh textu re of whole Saddletail snapper. From in
depth discussions with i ndustry stakeholders to develop strategies to address this
con u nd ru m , t h ree possible approaches were defined.
The aim is to differentiate fish with a higher probabil ity of exh ibiting TFS from the
rest of the catch . As male Saddl etai l are m uch larg e r than female of equivalent
age , length/age correlations are ineffective for Saddl etail snapper without sexing
the fish. So our focus tu rned to d iffe rentiating between males and fem ales of
mature age . A s u m m ary document was prepared on cu rrent applications of
sensi ng and i m ag ing tech nology.
viii
Managem ent of tough fish synd ro m e
There a r e several process ing tech nologies that may s h o w prom ise with respect to
m itigating the tough ness of flesh when cooked. These have been reported here
and com m u n icated to the stakeholders. There is valu e in a sim ple strategy based
on cons u m e r information. Experience suggests that stil l o n ly a sm all proportion of
the population has knowledge of Saddletai l snapper and its eating qualities.
Education on the texture of Saddletai l flesh and its su itabi l ity for specific cooking
styles may rem ove the cons u m e r su rprise at the firm ness of the fles h . Any such
prog ram m e wou ld need to h i g h l ig ht the positive qualities of Saddletail , of which
there are many.
Consensus among the key i ndustry stakeholders was for concept development of
enzym e processing treatment for tough f is h . Proof-of-concept trials u ndertaken
demonstrated add ition of a plant based protease prior to vacuum packag ing
supplied sig nificant im provem ent in cooked fil let textu re. Th is research has the
pote ntial to provide stakeholders with a valu e addition pat hway for fish identified
as high risk of developing TFS, and warrants f u rther i nvestigation within a
com mercial fish processing envi ronment.
KEYWO R D S :
Saddletai l snapper, Lutjanus
age, consumer percept i o n ,
malabaricus,
flesh tou g h ness, fish texture, fish
ix
Managem ent of tough fish syndro m e
TA BLE O F CONTE NTS
1.
Backgrou nd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.
The problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 . 2.
Cu rrent industry information
.
.
1
1 . 3.
Cu rrent science knowledge
.
2
1 . 4.
This project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 . Need
6
3 . Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. M ethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. 1 .
Planned field trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2.
Transport a n d log istics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3.
Sample processing ( H FSP Coopers Plains Q L D ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4.
Rigor assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.5.
Tem peratu re logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
4.6.
Texture analys is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 O
4. 7.
Sarcomere Length Determ i n ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
4.8.
Esti mation of fish age by otol ith increm ent and pred ictive m odel based on
otolith weig ht . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
4.9.
Consu m e r Assessment: Threshold of rejection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3
4. 1 0 . Statistical analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
5 . Resu lts and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5
5. 1 .
Rigor m o rtis prog ression and 'cold shock' ( FT6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5
5.1 . 1 .
Rigor m ortis prog ression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5
5 . 1 .2.
Sarcom ere Length Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
5.1 .3.
Cold Shock a n d Rigor mortis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
5 . 1 .4.
Tem perature logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
5.1 .5.
Field Trip S u m m ary ( FT6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.
Analysis of TFS across years and seasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.2. 1 .
Sam ple Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Texture data f o r a l l trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6
5.2.2.
Analysis o f resu lts b y field t r i p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7
5.2.3.
5.2.4.
Analys is o f resu lts b y t r i p a n d sex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 8
5.2.5.
Analys is o f resu lts b y estim ation o f f i s h age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1
5.2.6.
S u m m ary o f age, season and texture analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6
5.3.
Current applications o f sensing or imaging tech nology in fish biology . . . . . . 3 7
U ltrasound i m ag i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.3. 1 .
5.3.2.
N e a r infra-red spectroscopy ( N I RS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.3.3.
Potential supplier details : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1
5.4.
Consu m e r assessment o f Saddletail texture : Threshold o f rej ection with
regard to texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.4. 1 .
Resu lts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.4.2.
5.5.
Enzym e treatm ent of Saddletai l snapper to improve cooked textu re . . . . . . . . 48
5.5. 1 .
Trial 1 : Determ ination of effective dosage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Trial 2 : I ncreased dosage a n d efficacy over time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.5.2.
5.5.3.
Trial 3 : Short soak time treatme nts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1
5.5.4.
Trial 4 short soak t i m e a n d ove rn ight storage u nder vacu u m . . . . . . . . . . . . 52
5.5.5.
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4
6 . Benef its and adoption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
7. Further deve lopment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
7. 1 .
Cons u m e r threshold of rejection for cooked Saddletail snappe r . . . . . . . . . . . . . . . 57
Determ i n e efficacy o f u ltrasound imaging f o r determ i n i ng the sex of
7.2.
Saddl etai l snapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
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iii
Management of toug h fish syndro m e
7.3.
Optim isation o f e n zym e treatment o f Sadd letail snapper with in com m ercial
protocols
57
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. 59
8 . Planned outcomes
9 . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.1 .
Cold shorte n i n g and 'cold shock' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.2.
D rivers o f TFS i n Saddletail snapper. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0
9.3.
Available technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.4.
Consu mer preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.5.
E nzym e treatm e nt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
1 0.
11.
Appendix 1 : I ntel lectu al P roperty
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67
Appendix 2 : Project Staff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
1 2.
1 3.
Appendix 3 : Con s u m e r panel questionnai re
68
Appendix 4. Com m e nts from consum ers relating to question 6 and qu estion 7
1 4.
of the consumer assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
1 4. 1 . Like comm ents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
1 4. 2 . Dislike Com m ents
.
76
1 5.
Appendix 5: Discussion m aterial and stakeholder m eeting m inutes ( Novem ber
20 1 1 ) 81
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iv
Managem ent of tough fish synd rom e
LIST OF TABLES
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1 . Field trip and sample col lection summary across project. . . . . . . . . . . . . . . . . .
2 . Su m m ary of chilling treatm ents
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3 . Observed rigor stage and scoring system
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4 . Categories of texture used for consumer assessment . . . . . . . . . . . . . .
5 . Su m m ary o f sarcomere length analysis
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6 . Su m m ary of tem perature loggers . . . .
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...
7. Su m m ary of field trips
8 . Su m m ary of m ean resu lts for both sexes of Saddletail snapper . . . . . . . . . . . . . . . . .
9 S u m mary of field trip data for male and female Saddletai l snapper
1 0 . S u m m ary of r2 values from Figure 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 1 . Resu lts summary from consu m e r acceptabi l ity assess m ent.
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1 2 . S u m m ary of l i ke com ments relating to texture . .
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1 3 . S u m m ary of dislike com m ents relating to texture
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1 4. S u m m ary of trial 1 enzym e treatment. .
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1 5 . S u m m ary of Trial 2 treatments .
...
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1 6 . S u m m ary of day 1 resu lts for trial 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 7 S u m m ary of day 3 resu lts for trial 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 8 . S u m m ary o f resu lts from trial 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 9 S u m m ary of resu lts and com ments for Trial 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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v
Management of tou g h fish syndro m e
LIST O F FIGU RES
Figure 1 . Rigor assessment by observed fish flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
Figure 2 . l n stro n text u re analyser with sample loaded i nto the Kram er-Shear cel l . . . 1 1
Figu re 3 . Photograph of sample preparation for textu re assessment by l n stron . . . . . . 1 2
Fig u re 4 . Mean rigor scores over 4 hours for Saddletai l snapper i n three m ed i a
tem pe ratures (standard error bars are shown) .
.. . .
15
Figu re 5 . Tem peratu re logger i n bri n e tank ( red tag) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7
Figu re 6 . Daily temperatu re log of bri n e tank for all fishing day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8
Figu re 7 . Tem peratu re data for logger #26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
Figure 8 . Fi rst 48 hou rs of ch i l l i ng and storage for logger #26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
Figu re 9 . Tem peratu re data for logger #92 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figu re 1 0 . Tem peratu re profile from starboard fish hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1
Figu re 1 1 . B i n of frozen red Em peror d u ring u n load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1
Figu re 1 2. B i n of frozen m ixed Cod frozen together and emptied i nto ice b i n . . . . . . . . . . 2 2
Figure 1 3 . Mixed b i n of frozen Cod and Sadd letai l snapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figu re 1 4. Frozen Saddletai l i n m ixed bin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 1 5 . Saddletail snapper exh ibiting tem peratu re abuse sym ptoms . . . . . . . . . . . . . . . . . . 24
Figure 1 6 . Frequency h istog ram of text u re data for all fish (FT2 to FT8) . . . . . . . . . . . . . . . . . 27
Figure 1 7. Mean work done val u es for m ale and female Saddletail s n apper. . . . . . . . . . . 29
Figu re 1 8. Mean m uscle pH ( u ltimate) for male and female Saddletail snapper . . . . . . 29
Figu re 1 9 . Mean fish weight for male and female Saddletail snapper . . . . . . . . . . . . . . . . . . . . . . 30
Figure 20. Mean fork length for male and female Saddletai l snapper. . . . . . . . . . . . . . . . . . . . . . 30
Figu re 2 1 . Relationship ( l i near) between fish age and otolith weight for all Saddletai l
snapper collected during FT3 and FT5 ( n =2 1 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1
Figu re 22. Estimated age and work done for all fish from FT3 to FT8 (n=373) . . . . . . . . 32
Figu re 23. Estimated age and work done for FT3 (r2 =0.65), FT5 (r2 =0 . 47) , FT?
( r2 =0. 27) and FT8 (r2 =0. 57) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figu re 24. Estimated age and work done for all trips and both sexes . . . . . . . . . . . . . . . . . . . . . . 33
Figu re 25. Estimated age and work done (all trips) for all female (r2 =0. 5 1 ) and m al e
(r2 =0. 42) Saddl etai l snapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figu re 26. Estimated age and work done (all trips) for Saddletail snapper landed in
autu m n (r2 =0.4 7) and spring ( r2 =0 . 49) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 27. The H itach i Aloka SSD-500V portable convex sector/l i n ear u ltrasound
scanner commonly used i n small animal appl ications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figu re 28. An i m age from Davis et al (2006) showi n g the use of the SW- N I RS device
40
on a C h i nook salmon
Figure 29. Age categories of consumer pan e l lists . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 3 0 . Seafood pu rchase freq u ency of panell ists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 3 1 . Seafood pu rchase frequency of panell ists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figu re 32. Com monly pu rchased seafood products for panellists ( n = 1 38) . . . . . . . . . . . . . . . 44
Figure 33. Trial 1 sam ples after 24 hours storage at 4 "C
...
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49
Figu re 34. Sam ples prior to assessment during Trial 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 3 5 . Cross section of control sam ple from Trial 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 36. Cross section of 50g/L enzym e treated sam ple from trial 4 . . . . . . . . . . . . . . . . . . . . . 53
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vi
Manag e m e nt of tough fish syndrome
1 . Backg round
Saddletai l snapper constitutes a sign ificant proportion of the catch i n offshore
f i nfish fisheries i n northern Australia. A small but s i g n ificant proportion of these
fish beco m e 'tough' at the point of cookin g , res u lting in an i n edible product.
Cu rrently it is not possible to identify affected fish earl ier than the consumer plate.
The occu rrence and the lack of any m ethodology to detect or manage Tough Fish
Syndro m e (TFS) is responsible for a strong consu m e r backlash which has
resu lted i n a su bstantial reduction in price, cancel led orders and wasted product.
Th is project proposal is a di rect res u lt of primary f i nd i ngs from FRDC proj ect
2008/208 Improving profitability to Industry through the identification and
management of 'tough fish syndrome' in tropical Saddletail snapper (20 1 0). The
findings from FRDC 2008/208 evidence su pport of a correlation between season
and flesh firm n ess, but it is insufficient to defin itively identify the causative age nts
or form u l ate managem ent options for the syndro m e . There may also be other
influencing factors. To e l i m i n ate u n l i nked i nfluences and gain m eani ngfu l data on
which to develop m anagem ent strateg ies, it is proposed that s i m ilar m ethodology,
as used in 2008/208, continue to be appl ied t h rough this proposed project.
The proj ect application for 2008/208 was developed at the specific urging of the
reef fish val ue chain in the Northern Territory, Queensland and Western Austral ia.
I ndustry stake holders i n all th ree j urisd ictions are sufferi ng large reven u e losses
caused by TFS. Outcomes from the research (both 2008/208 and this proposed
proj ect) d i rectly add ress the profitabil ity issues of reef fish fisheries and the local
and export demand for reliably h i g h q u al ity Australian product.
The prim ary challenge is to positively identify the cause of the syndro m e (wh ich
FRDC 2008/208 has, in part, ach i eved). This wi l l facil itate development of
management strateg ies to re-instill consu mer confidence i n the quality of
Saddletai l Snapper and reef fish in general .
1. 1.
The problem
TFS is exh ibited by some tropical reef fish i n which the textu re of the flesh
tou g h ens severely after cooki ng, rendering the fish i nedible. Such flesh toug h n ess
only man ifests its self on the consu m e r plate. P rior to this poi nt the fish is not
visually different to any other fish, the fish f i l l et and the raw flesh has sim ilar
textu re to that of non-tough fish, but u pon cooking a 'to u g h ' fish wi ll have a texture
that is described as "extremely rubbery" , "car tyre-like" . Market awareness of the
risk is now widely entrenched with buyers refusing to handle specific reef fish.
Queensland wholesalers (Cardi nal Seafoods, Mackay Reef Fish Supplies) refuse
to buy Grass Em peror off the boats as they consider the i ncidence of TFS to be
u n acceptably h i g h . TFS is consequently causing sign ificant reve n u e loss for the
industry, as fully evidenced by the recent cancellation of large retail supply
contracts for Saddl etai l Snapper.
1.2.
Current industry information
TFS has been observed for several years, with i ncreasing reported incidence over
the last th ree to four years . As most of the avai lable evidence is subjective , it is
difficu lt to accurately state the real i ncidence. Rigorous data on the i ncidence of
Management of tou g h fish syndrome
TFS wit h i n catches is n eeded to quantify the problem and determ i n e the causative
factors .
TFS h as been reported across all Australian tropical reef fish fisheries and i n fish
caught by all m ethods of captu re : dropli n e , trap and trawl . The problem appears to
be pervasive and affects a sign ificant proportion of several com m e rcially
sig n ificant species . Most tropical snappers are affected and specifical ly, species
such as Saddletail snapper, Crimson snapper, Red em peror and Golden snapper
are i m p l icated . Reports indicate that occu rrence is not consistent, with only a
proportion of fish from any one catch affected. There are no obvious com m on
factors denoting which fish will be 'toug h ' although col loqu ial evidence s u ggests
that larger fish (>3kg) are more l ikely to exh ibit this syndrome.
Com m u n ications with stakeholders reveal that Saddletail snapper is a dom i nant
part of a m u lti-species fishery across the tropics. All fish landed m ust be m arketed
because retu rning lowe r-val u e species to the water is not an o ption. A large
proportion of ' redfish' in a catch severely reduces the profit marg i n for any given
trip, so much so that the species is often sold with a m i n imal or no marg i n s i m ply
to preve nt wastage.
Round table d iscussions with m ajor stakeholders i n the fishery i l l icit the belief that
TFS cou ld also be i nfluenced by cooking m ethod or style. They suggest a
sim ilarity of situation as with d ifferent beef cuts - g ravy beef and eye f i l l et steak
are not appropriate for sam e cooking tech niques. I ndustry was keen that this
proj ect proposal consider this aspect and as such, a cooking com po n ent has been
incorporated i n this applicatio n .
Dialogue with those i nvolved i n reef fisheries across northern Austral ia, indicates
there are locational d ifferences related to the i ncidence of TFS. It appears that
large Sadd letail Snapper (9-1 0kg) reg u l arly cau g ht off Agnes Waters (at the reef
drop-off, l ower Queensland east coast) do not exh i bit TFS. S i m i l arly, m ost
Saddletai l snapper caug ht in m id-latitude Western Australian waters are not
'to u g h ' . The syndro m e seems to only be prevalent in fish caug ht in tru ly tropical
latitudes across northern Australia. Again, the i ndustry is eager to u nderstand
whether this is, i n fact , a reality and if it is the case - why?
1.3.
Current science knowledge
Textu ral variation issues in fish m uscle text u re has previously bee n identified in
m any species including Atlantic halibut (Hagen et al. 2007) , Atlantic Cod ( Love
1 979) and Japanese ayu ( Ito et al. 1 992). H owever, the m ajority of research has
focused on issues s u rrou nd i n g the potential for tissue to soften or g ape post
harvest rather than excessive f i rm ness of the cooked m uscle.
Tough ness issues i n terrestrial ani m al sou rces of m eat have been broad l y
investigated a n d reported . Two extensive reviews in this area have been
pu blished by Shorthose and H arris ( 1 9 9 1 ), and Harper ( 1 999 ) . What is clear fro m
these reviews is the natu re o f the relationship between m uscle struct u re,
physiolog ical function , phenotype, gene expression and l evels of m etabolic
enzymes is so com plex as to make determ inations of cause and effect with
respect to meat tough n ess extrem e ly difficult ( H arper 1 999) . Upon the d eath of an
an imal adenosi n e triphosphate (ATP) production ceases and the actinomyosin
com plex becomes m o re tightly associated . This is the process cal led rigor mortis.
The rate at which rigor mortis com m e nces is d riven by the level of g l ycogen
present within the m uscl e .
Forrest a n d Poole (20 1 2)
2
Management of tough fish syndrome
However the relationship between m u scle g lycoge n , u ltimate m uscle pH,
sarcomere length and tou g h n ess is a com plex relationship. I n short, beef from a
non-stressed an i m al rapidly ach ieves a p H <5 . 7 before the onset of rigor mortis
(Tornberg 1 996) . Howeve r, pre-sl au g hter stress depletes the amou nts of m u scle
g lycogen and slows the rate of pH reduction post mortem . Devi ne and Crystal
( 1 998) have demonstrated that m uscle tou g h n ess wi l l be m axim ised if the a fi nal
m uscle pH falls i n the range of 5 . 8-6.2.
Pre-s laug hter stress has also been identified as playi ng a role i n fish m u scle
qual ity. G lycogen depletion res u lting f rom pre-s lau g hter stress reduces the time
taken to go i nto rigor mortis and can also cause a stronger rigor mortis. Sig holt et
al ( 1 997) demonstrated 1 0 m i n utes of pre-s laughter stress i n farm raised Atlantic
sal mon ( Sa/mo salar) resu lted in sign ificantly softer f i l l ets measu red by texture
analyser and descriptive sensory analys i s .
T h e role o f nutrition has b e e n identified a s b e i n g a sig n if icant factor i n t h e quality
of Atlantic cod ( Gadus morhua) by Love ( 1 979 ) . More recently, starvation prior to
slaug hter has been demonstrated to s i g n if icantly i ncrease the hardness of raw
f i l l ets (E i n e n and Thom assen 1 998) . Howeve r this effect was not apparent afte r 1 2
days storage on ice, and a sensory panel fou nd the starved fish (between 30 and
86 days) to have a sign ificantly decreased fresh flavou r. E ien and Thomassen
concluded starvation prior to slaughter was a weak tool for chan g i n g f i l let quality in
Atlantic salmo n .
Beef sarcom eres with i n t h e myofibril lar structure tend t o shorten du ring rigor
mortis ( D ransfield 1 992) . However, the m echanism for shortening is not wel l
understood. Carefu l tempe rature control du ring t h e f i rst 2 4 hours post-slaug hter
has been identified as a key preventative m easu re to reducing the i m pact of
sarcom e re shortening ( Koohm araie et al. 1 996) . Beef m u scles that are stretched
u nder tension by attachment to im mobile bones rarely demonstrate short
sarcomeres ( Harris and Shorthose 1 988) .
Very l ittle research i nvestigating the relationship between fish m uscle sarcom ere
length and textu re has been published. Yoon et al ( 1 9 9 1 ) exam i n ed fish m uscle
sarcom ere lengths d u ring investigation i nto the relationship between
trimethylam i n e oxide (TMAO) i n freeze induced texture changes observed in
frozen fish m ince. Yoon concluded that TMAO had no role i n the developm ent of
tough ness in m i n ced fish m uscle. Sig u rgisladottir et al (200 1 ) i nvestigated the
d ifferences in m uscle m icrostructure and textu re of fresh and smoked farmed
Atlantic sal m o n ( Sa/mo salar) . Muscle fibres were fou nd to shorten during the
salti ng and dryi ng process. However sarcom e re lengths did not change.
In beef the two prim ary sou rces of textural variation are con nective tissue and
m yofibril lar structu re ( Harper 1 999). These structu res are also considered by
Harper to i nteract m echan ical ly. Harris and Shorthose ( 1 988) and others suggest
m yofibril lar structu re contributes more than con nective tissue with regard to overal l
tough ness i n beef. However Kuypers and Kirth ( 1 995) determ ined that con nective
tissue did m ake a contribution towards tou g h n ess in beef, and this contribution
was disproportionally g reate r than wou ld be expected with respect to the weight of
con nective tissue i n muscle.
Collagen content has previously been identified as having a d irect i nflue nce on the
textu re of raw fish (Sato et al. 1 986) . More recent authors have achieved m ixed
resu lts. Li et al (2005) demonstrated no relationship between f i llet firm n ess and
3
total col lage n content and a weak relationship (p=0 . 057) between alkal i i nsolu ble
col lagen and f i llet f i rm ness . Whereas Hagen et al (2007) fou nd a stronger
rel ationship (p<0. 00 1 ) between alkal i i nsoluble col lagen and f i llet texture
describing 24% of the observed variation.
Perhaps of more interest is the form ation of m ature i ntermolecu lar cross - l i n ks
between collag e n fibres ; providing tensile strength to the col lage n fibres . The
form ation of these cross- li nks has been determ ined to occu r with age wit h i n the
con n ective tissue m atrix ( Bailey 200 1 ). Both Li (2005) and Hagen (2007) identifi ed
a strong relationship between the m ature col lagen cross- linking com po u n d ,
hyd roxylysyl pyrid inoline ( PYO) , a n d raw texture in Atlantic S a l m o n (Li et al. 2005)
and Atlantic Hal ibut ( H ag e n et al. 2007) . The l i n ear relations hip identified by
Hagen accou nted for up to 64% of observed variation.
A f u rther com plication su rrounds the role of cooki ng i n determ i n ation of meat
tou g h ness. Several authors have identified low correlations betwee n the
tou g h ness of cooked beef and the properties of raw meat ( Devine and Ch rystal!
1 99 8 ; Lepetit and Culioli 1 994) . Cooking has also been previously u nsu itable for
rheolog ical testi ng of fish m uscle ( D u n ajski 1 980) . E i n e n and Thom assen ( 1 998)
have also suggested that pre slaughter starvation effect raw and cooked fillets in
diffe re nt ways .
Many factors have an influence on the eating quality of flesh textu re i n fish. These
factors include:
1 . Physio log ical factors such as size, condition , age, g ender and sexual
matu rity, season , m uscle structure, collag e n content, diet and capture
location;
2 . Capture m ethods including i m m ediate post-captu re hand l i n g , onboard
chilling m ethod and storage t i m e ;
3 . Cooki ng practices including cooking m ethod, cooking t i m e ; and
4. Phase of rigor mortis of the fish at cooki n g .
U nder ideal hand l i n g conditions, tropical fish go i nto a n d through r i g o r m o rtis
slowe r and m ore gently than temperate species (Cu rran et al. 1 98 6 ; Poole 1 99 1 ) .
I t is also known that tropical fish can suffer from 'co ld-shock' syndro m e s i m i lar to
that occurring in beef carcasses when chilled suddenly (Cu rran et al. 1 986) .
I nvestigations using nucleotide analysis with i n the F R D C 2008/208 failed to reveal
any s i g n ificant cold shock event, however this can not be com pletely discou nted .
Analysis of sam ples by e lectron m icroscopy (carried out as part of the work)
revealed a trend that suggested a cold shock event m ay have occu rred wit h i n fish
exh ibiting tou g h ness.
Textu ral i rreg u l arities have been demonstrated to be seasonal in some fish
species ( Hage n et al. 2007) . Specifical ly, d iffe rences i n col lagen types present,
their rol e and deg ree of cross-l inking of collagens is associated with textural
variab i l ity in raw f i llets . For exam ple, Hagen demonstrated that aquacu ltu red
halibut harvested in spring wou ld res u lt in firmer texture than other s easons.
Resu lts from the cu rrent study ( F R DC 2008/208) being u ndertaken h ave
illustrated a sig n ificant difference between the textu ral firmness of Saddletai l
snapper cau g ht i n late spring/early s u m m e r to those cau g ht i n autu m n . S i g nificant
diffe rences were also observed between m ale and female fish caught i n early
s u m m er. However, these d ifferences were less s i g n ificant when fish were
capt u red i n aut u m n .
4
Management of tough fish synd ro m e
1.4.
This project
Th is proj ect bu i lt upon the resu lts al ready obtained from the previous study ( F R DC
2008/208) to obtain a clearer u nderstanding of the role of seasonal effects. The
role of 'cold shock' i n the developm ent of TFS has also been investigated.
Stake holders have also been provided with a review of non-i nvasive tech nologies
that m ay assist i n identifying fish with a h i g h risk of developing TFS , as we l l as
som e product concepts that di rectly add ress the use of fish exh ibiting TFS.
5
2 . Need
Data o btai n ed from field trips as part of the current project ( F R D C 2008/208)
indicate the development of TFS m ay not be due to inappropriate onboard
handl i n g practices. Textural issues appear to be due to a com b i n ation of
biological, g eog raph ical and seasonal factors . Resu lts from the cu rrent research
suggest a s i g n ificant i nfluence of both sex and season on the tou g h n ess observed
in Sadd letail snapper. Cu rrent fi ndings do not discount potential compou nding
influences such as 'cold shock' for exam ple.
The need for stakeholders is to develop an u nderstanding of these effects o n the
developm e nt of TFS within the Sadd letai l s n apper resou rce. Once this has been
ach i eved, strategies can be developed to best m anage the issu e . This m ay
i nvolve the use of non-i nvasive technology to identify fish at risk of exhibiting TFS
and remove them from the supply chai n .
Further work is also requi red t o f i nd su itable m arkets f o r fish identified a s h i g h risk
of TFS. This m ay i nclude novel product concepts not cu rrently utilised with the
val u e added seafood product market.
These outcom es wi ll al low stakeholders to m arket their prem i u m product with
confidence, ach ieve an i ncrease in price com m ensu rate with pre m i u m qual ity reef
fish and ensure the ongoing sustai nable use of the resou rce. And also su pport the
developm e nt of val u e added seafood products from those fish identified as high
risk of developing TFS.
Th is proposed project addresses the focus of i ncreas i ng profitabi l ity and optimum
util isation of fish identified by the NT, Old and WA with i n their respective cu rrent
fisheries research and developm e nt priority docu m e nts.
6
3.
Objectives
1 . To identify any post-capture practices that may i nf l u ence the occu rrence of
TFS
2. To identify l i n ks between TFS and specific physiological factors i n tropical
Saddletai l s napper
3 . To establish variabil ity of TFS in relation to season and capture location
4. To develop reco m m e ndations and strateg ies for i ndustry stakeholders to
m i n i m ise the im pact of TFS
5 . T o com m u n icate findings and recommendations to stake holders a n d assist
with the i m plementation of any changes to cu rrent fish ing and handling
p ractices
7
Management of tou g h fish synd rom e
4.
4. 1.
Methods
Planned field trips
Three major field trips were conducted over the cou rse of the project . A s u m m ary
of the field trips is presented in Table 1 . The trial names used for this project are a
conti n u ation from those i n the previous work ( F R D C project 2008/208) .
.
. t.
Ta bl e 1 . F1e Id trip an d samp e co II ect1on summary across pro1ec
Total Fish
P roject
Trial Name
Season/Vear
Fishi ng/Transport
2008/208
FT1
Oct 2008
Trap/Fresh
50
2008/208
FT2
Dec 2008
Trawl/Frozen
111
2008/208
FT3
Apr 2009
Trawl/Frozen
1 01
2008/208
FT4
J u n e 2009
Trap/Frozen
31
2008/208
FT5
Oct 2009
Trawl/Frozen
1 09
20 1 0/207
FT6
Oct 2 0 1 0
Trap/Fresh
45
20 1 0/207
FT?
Dec 2 0 1 0
Trawl/Frozen
99
20 1 0/207
FT?
Dec 2 0 1 1
Trawl/Frozen
83
4.2.
(629)
Transport and logistics
Fish landed fres h were packed i nto approved air freig ht Styrofoam boxes and sent
to Brisbane by Austral ian Ai r Express the same day. Fish landed frozen were sent
to Brisbane by frozen truck transport.
4.3.
Sample processing (HFSP Coopers Plains QLD)
Fish were kept frozen at -29 "C prior to processi n g . Fish were allowed to relax at
4 "C for 24 hou rs and then i m m ersed i n am bient tap water for 2 hours prior to
fil leting and sam ple collectio n . Fork length, weight, sex, and u ltimate pH of m uscle
were recorded at this time. M u scle pH was recorded using a TPS pH u n it (Model
n u m ber WP 80, Spri ngwood , QLD).
4.4.
Rigor assessment
The prim ary aim of th is experim ent was to determ ine whether 'cold shock'
previously observed in tropical species (Cu rran et al. 1 986; Parry et al. 1 987)
cou ld be forced by standard com m e rcial fish practices applying to Sadd letai l
snapper. And if so, determ ine whether this 'cold shock' phenomenon causes a
shorten ing of m uscle fibre sarcomere length as is seen du ring 'cold shorte n i n g ' i n
land based anim als carcasses.
Live landed Saddletail were euthanased by brain spike prior to i m m ersion in the
chi ll i n g media. Three temperatu re profiles were utilised for the chilling process
di rectly after euthanasia. These were ice s l u rry ( 0 - 1 "C) temperate seawater ( 1 2-
8
Manag e m e nt of tough fish syndro m e
1 5 "C) and ambient seawater (29-30 "C) . A total o f 1 5 f i s h were assessed per
treatm ent. A s u m m ary of the treatm ents is presented i n
Table 2 . Su mmary of c h i l l i n 1 treatments.
Treatment
Tem perat ure
No of fish assessed
Ice Slu rry
0-2 "C
15
Tem perate
1 2- 1 5 "C
15
Ambient
29-30 "C
15
Sam pled fish were assessed for rigor development prior to i m m ersion and then
every 30 m i n utes for 4 hours. After wh ich, fish we re transferred to the brine tank to
cont i n u e c h i l l i ng and storage as per the standard protocols of the vessel .
Rigor assessment was ach ieved b y use of a f ive point category scale t o describe
the state of rigor. The five categories correspond approximately to the angle of
flexi bil ity observed in the fish. Fish were scored as presented i n Table 3 .
.
Tab l e 3 Ob served riQor staQe an d sconnQ svstem.
Presence of rigor
Observed bend i n fish
horizontal)
( 0 of bend from
R i gor score
No rigor
-go o
1
Some rigor
-60-70 °
2
Moderate rigor
-45 °
3
S i g n ificant rigor
-20-30 °
4
Fu l l rigor
-o o
5
Sam pled fish were placed right-hand side down on a nylon cutting board so that
the tail would hang over the edge of the board . Each fish was pos itioned so that
the end of the pelvic f i ns aligned with the edge of the board to allow for equ ivalent
tai l hang. Also, the fish was positioned so that a line from the end of the pelvic fins
to the bottom jaw l i n e was perpendicu lar to the edge of the board . This m ethod is
illustrated in Figure 1 .
9
Figu re 1 . Rigor assessment b y observed fish flex i b i l ity.
To confi rm the prese nce of 'cold shorte n i n g ' , tissu e samples were taken for laser
diffraction analys is as described by ( Bouton et al. 1 973) . Sarcom ere l engths were
m easu red using a h e l i u m -neon gas laser diffraction tec h n ique on u nf ixed portions
taken from frozen (-20 °C and -80 °C) sam ples. The laser has a wavelength of
635 n m , and was used as the l ight source to obtain diffraction patterns from
m uscle f ibre sam ples held between glass m icroscope s l ides .
This process provides a n accu rate m easu re o f sarcom ere length and m uscle
fibres exhibiting cold-shorten i n g wi l l display sign ificantly shorter sarcomere length
than non-affected m uscles. This work was com pleted by An ita Sykes and Janet
Stark of CSI RO Food and N utritional Sciences, Coopers Plains.
4.5.
Temperature logging
Tem peratu re logg ing of 2 whole fish, brine tank, and both fish holds, was
conducted during FT6. using a Therm ocron tem perature logger (OnSolutio n ,
Bau l kham H i lls, N SW). Tem pe ratu re values were taken every 1 5 m i n utes.
4. 6.
Texture analysis
Textu re analysis was performed on cooked portions of Saddletai l f i l let. The left
side of the fish was always used as the rig ht side h ad tissue sam ple taken from it
and resu lts wou ld have been com prom ised .
Fillets were vacu u m -packed i nto plastic bags and steamed at approximately 95 °C
for 20 m inutes . The f i l l ets were then allowed to return to room temperatu re (24 °C)
prior to texture analysis. This wou ld take approximately 2 hours .
Analysis was conducted o n an l nstron 5543 texture analyser ( l nstron Corporatio n ,
8 2 5 U n iversity Ave n u e , Norwood M A , U SA. ) u s i n g a S O O N load cel l a n d a
mod if ied Kram er-Shear cel l . The m od ification was to rem ove two of the five
10
Manag e m e nt of toug h fish syndro m e
blades. This was decided after a fish ide ntified a s bei ng tou g h i n prel i m i n ary
assessme nts gave val u es that were i n excess of the load l i m it of the cel l . Figure
2shows the l nstron i n use with a sample of Sadd letail i n the modified Kram er
Shear cel l .
F i g u re 2 . l nstron textu re a nalyser w ith sample loaded i nto the Kramer-Shear cel l .
Two sam ples per fil let were taken for assessment. These sam ples were taken
longitudi n al l y from the shou lder end of epaxial myoto m e . The sam ples we re
placed with i n the cell so that the blades were cutting across the d irection of the
m uscle fibres. A photog raph of a f i l let be ing sampled is presented i n Fig u re 3 .
Forrest and Poole ( 20 1 2 )
11
Fig u re 3 . Photograph o f sample p reparation for textu re assessment b y l nstron.
Two forms of data were collected during this analysis. The first is peak force of
shearing and is expressed in newtons ( N ) . This is the m axim u m force req u i red to
shear the cooked m u scle. The second is total energy req u ired to shear the cooked
m uscle and is expressed in m i ll ijou les (mJ ) . The resu lts presented here are also
d ivided by the we ight of the sam ple (g) and expressed i n m i l l ijoules per g ram
(mJ/g ) .
4. 7.
Sarcomere Length Determination
Sarcom ere l engths were m easu red using a heliu m - neon gas laser diffraction
tech n ique on u nf ixed portions taken from frozen (-2o · c and -80 'C) samples. The
laser h as a wavelength of 635nm , and was used as the light sou rce to obtain
d iffraction patterns from m u scle f ibre sam ples held between g l ass m icroscope
s l ides. Sarcom ere length was dete rm i n ed from the d iffraction pattern displayed on
a f rosted screen ( Bouton et al. 1 973) . S arcom ere length ( µ m ) was calcu lated from
the average d istance ( m m ) of the i n n e r and outer diffraction bands from the centre
of the screen. The m ean of 4 readings was taken per sample (not every sam ple
had 4 read i ngs) . This work was com pleted by Anita Sykes and J anet Stark of
CSI RO Food and Nutritional Sciences, Coopers Plai n s .
4.8. Estimation of fish age by otolith increment and
predictive model based on otolith weight
Fish age data was sought after analysis of resu lts from FT2 in 2008 ( Forrest et al.
20 1 0) . During this work, a small but sig n ificant relationship was identified between
fork length and work done. From this point o n , oto l iths were collected from all field
trips . H owever, otol iths were not col lected d u ring FT2 and no age data exists for
those fish sam pled.
12
Manag e m e nt of toug h fish syndrom e
Saddl etai l collected d u ring f ield trips FT3 and FT5 were exam i n ed for age
estimation
with the ass istance of Queensland Fisheries staff from Southern Fisheries Centre,
Deception Bay using the standard m ethod of increment determ ination of otol ith
cross-sections (Fisheries-Queensland 2009) .
During the cou rse of this work our access to Queensland Fisheries became
seve rely l i m ited and another m ethod of fish age estimation was sought. The age
data collected from FT3 and FT5 was used to develop a predictive ( l i near) m odel
that wou ld assist in providing an estimate of fish age from otol ith weight.
4.9.
Consumer Assessment: Threshold of rejection
Sam ples of Saddletai l snapper used for this assessment were dupl icate fil lets of
the previous field trip used for textu re determ inations (field trip 8) . U pon i n itial
processi n g , the left side fil let is used for texture assessment, and the right s ide
f i llet is kept frozen for retent ion (-29 "C ) . It is these right side f i l l ets that were used
for consu m e r assessm ents.
As these fish have all been assessed for cooked texture, we can establish
categories of textu re valu es for sam ples to be allocated to. For this assessm ent,
fou r categories of texture were established. Textu re values are expressed in
m i l l ijoules per g ram (mJ/g) of cooked fish sam ple. These are presented in Table 4.
Table 4. Catego ries of textu re used for consumer assessment.
Texture category
Texture range (mJ/g)
Mean texture (mJ/g)
1
35.43 - 40 . 1 4
37.58 (±1 .82)
2
48 . 0 1 - 5 1 .05
49.66 (±0 .99)
3
55.80 - 63.59
59.40 (±2 .83)
4
68.33 - 76.48
7 1 . 9 8 (±2 . 5 1 )
Consu m e r assessments are usually conducted via one of two bas ic m ethods. The
first invo lves the use of category or l i n e-scales to determ ine how m uch a
cons u m e r either l i kes or d is l i kes a product. Category scales involve using an odd
n u m ber of categories ; usually five, seven or n i n e categories. The prem ise of this
style of assessment is to obtain a qu antified val ue of l i keness or dislikeness. This
m ethod is usually em ployed when com pari ng products against each other. The
authors h ave previously been used category scale consumer assessment of new
apple varieties i n com parison to cu rrent com m ercial apple cu ltivars (Zeppa 2007) .
However for the pu rpose this assessment a bin ary forced selection m ethod was
determ i ned to be m ore applicable . I n this method, consum ers are forced to m ake
a selection to accept or reject a sam ple on any g iven or su ite of parameters.
S i m ilar assessm e nts have previously been conducted a broad range of
consu m e rs products including rancidity in m il k (Hough et al. 2004) and beef
( Platter et al. 2003) . This m ethod is also used i n non-food consumer appl ications
l i ke mobile m u lti-media i m age qual ity (Jum isko- Pyykk et al. 2008) . For this
assessm ent a level of rejection was deemed to be 50% of consumer responses.
This is consistent with the work of Hough et al (2004) and others .
Sixty ( 6 0 ) consumers o f seafood were recru ited from staff on s ite at 39 Kessels
Road Coopers Plains (Queensland Governm ent) . Panell ists were qual ified as
13
bei n g those who consu m ed seafood at least once a month. Consumers were also
asked demographic questions on seafood buying prefe rences and frequencies.
F i l l ets of Saddl etail were prepared i n the same manner as that used for the i n itial
texture analys is (Forrest et al. 20 1 0) . Whole fillets were vacu u m -packed in barrier
bags and steamed i n a U n ox LineMiss ™ steam er oven (Model X F 1 35 Padova,
Italy) at 95 'C and 60% h u m idity for 20 m i n utes . Fillets were then allowed to rest
for 5 m i nutes at am bient tem perature (24 'C) and then cut in sam ple portions of
approximately 2cm x 2cm squ are. Samples were then placed in small foi l trays
and a l ayer of foil was wrapped over the tray. Sam p l es were then retu rned to an
oven set at 65 'C u ntil panell ists were ready to receive samples for assessm ent.
Assessments were conducted in the sensory booths at Coopers Plai n s . The
questionnaire was com pleted via com puter us ing Compusense® Five (Guelph,
Ontario, Canada) . Panell ists were presented the four samples in a random i sed
order.
Consu m ers were asked "Please find sample XX and taste a portion of this sample.
Is the texture of this fish acceptable to you ?' Answers available to con s u m e r were
either " Yes, this texture is acceptable to me" or "No, this texture is unacceptable to
me and I would reject this dish." Consu m ers were then asked to com m ent o n any
aspects of the sam p l es that they liked or disl iked.
A pri nted copy of the q u estion nai re in fu l l can be fou nd i n Appendix 3 .
4. 1 0. Statistical analysis
Statistical analysis was conducted using GenStat Fou rteenth Edition , vers ion
1 4. 1 . 0 .5943 s u pplied by VSN I nternational Ltd (www.vs n i . co . u k)
14
5. Res u lts and d iscussion
5. 1 .
5. 1 . 1 .
Rigor mortis progression and 'cold shock' (FT6)
R i g o r m o rtis prog ress ion
No s i g n ificant d ifferences i n t h e speed o f rigor development were identif ied
between the th ree ch i l l i ng m edia tem perat u res previously described (Table 2).
However, a trend i n the developm ent of rigor is apparent from comparison of the
m ean val u es for fish from each of the c h i l l i ng m ethods (Fig u re 4) . Fish subjected
to ice slu rry prog ressed to rigor at a faster rate than fish held at warmer
temperatu res without exh ibiti ng any instantaneous stiffen i n g as is the case i n 'cold
shock . ' The variabil ity between fish wit h i n each ch i l l i n g system is large though as
indicated by the error bars i n Fig u re 4.
- Ice Slurry
- 1 2 - 1 5 Degrees C
- 29-30 Degrees C (Ambient)
T
T
I
0.0
0.5
1 .0
1.5
2.0
Time (hrs)
2.5
3.0
3.5
4.0
4.5
F i g u re 4. Mean rigor sco res over 4 h o u rs fo r Sadd leta i l snapper in t h ree med ia
temperatu res (standard error bars are shown).
Som e of the variabi lity between i nd ividual fish is explai n ed by the fish ing method.
The fish are wild cau g ht by trap and, as such, the amo u nt of stress experienced
can not be controlled, qu antified or avoided. The pre-existing physiolog ical
condition of the fish is also an u n known . This has strong beari ng as stress
experienced by the fish rapidly depletes the levels of ATP present in the m uscle,
the onset of rigor may be accelerated by the amount of time spent i n the trap prior
to harvest.
The suggestion that temperatu re has a di rect influ ence upon the deve lopm ent of
rigor is reasonable and consistent with the work of Jerrett et al (2002) . Jerrett
demonstrated that in P i n k snapper ( Pargus auratus) post-mortem metabolic rates
sharply increased below 6 ° C and above ,1 6 "C. The lower th reshold is also i n
agreement with the work o f Iwamoto ( 1 987) a n d Watabe ( 1 989) .
The u pper l i m it identified by J errett is not consistent with the data represented i n
Fig u re 4. H owever, the val ue o f 1 6 "C a s the u p p e r threshold determ i n ed by Jerrett
15
is close to the m ean annual sea tem peratu re reported i n their work (being 2 1 'C i n
s u m m e r and 1 O 'C i n winte r) . With sea temperatu re i n t h e Arafu ra S e a being
sign ificantly higher than this range, and with far less seasonal variatio n , it m ay be
reasonable to suggest that the upper threshold for Saddletail snapper wil l be m u c h
closer to am bient tem peratu re (29-30 'C) t h a n 1 6 'C a s reported b y Jerrett.
5 . 1 . 2 . Sarco m e re Length Analys is
No sig n ificant differences were observed between the sarcomere lengths of
m uscle sam ple from each of the treatment m ethods. A s u m m ary of these resu lts
are presented in Table 5.
I
.
Ta b l e 5 S u mmary o f sarcomere eng th ana1ys1s.
Treatment
Mean Sarcomere Length (µm)
Standard Deviation
Ice s l u rry ( n = 1 4)
1 .9 1
±0.06
1 2- 1 5 'C ( n= 1 5)
1 .92
±0 . 09
29-30 'C ( n = 1 5)
1 .96
±0. 1 0
Very l ittle d iffe re nce was observed betwee n the sarcom ere lengths of m uscle
fibres from the t h ree treatments. Total rang e of val u es for all treatments was
1 . 78 µ m to 2.08µ m . Previous work in beef m uscle (Smu lders et al. 1 990) h as
demonstrated cold-shortening effects need to res u lt i n sarcomere lengths less
than 1 . 65µm for trai n ed cons u m e r panellist to indicated a sig n ificant reduction in
perceived cooked meat te nderness.
5 . 1 . 3 . Cold S h ock a n d R i g o r m o rtis
Sadd letail snapper sam pled i n t h i s work h ave prog ressed t o rigor mortis faster i n
ice slu rry t h a n i n am bient temperature, althou g h the differences observed i n t h i s
work were n o t statistically significant.
Howeve r, when com paring sarcom ere lengths from m uscle fi bre with i n the sam e
treatm ents, there is very l ittle difference between any of the resu lts between any of
the treatm ents. Therefore the m echanism observed here where colder
temperatu re resu lt i n fast rigor development is u n l ikely to be a 'cold-shorte n i n g '
event a s previously s e e n i n land based ani m al carcasses s u c h a s beef ( Bouton e t
al. 1 973) .
An increase i n the rate of post mortem ATP depletion wou ld hasten the
development of rigor mortis as its onset is dete rm ined by the com plete exhaustion
of free muscle ATP ( Love 1 980) . This m ay be descri bed as a 'cold-shock' as
previously observed by Cu rran et al ( 1 986) , however this m echanism appears to
res u lt in very l ittle change in sarcom ere length and the refore cannot be attributed
to a 'cold-shorte n i n g ' event.
5 . 1 . 4 . Temperatu re logg i n g
Of t h e six temperatu re loggers used t o m o n itor several aspects of t h e ch i l l i ng and
storage process d u ring this trial , only four were successf u l ly retrieved . A s u m m ary
of the location of these loggers is prese nted in Table 6 .
16
Managem e nt of tou g h fish syndrom e
Table 6. s u m mary of tem peratu re loaaers.
Logger ID
Locat i o n
Data retri eved
#86
Brine tank (return i nlet cage)
No (logger destroyed)
#1 6
Brine tank (side baffle su pport)
Yes
#26
Day 2 Sadd letai l ( inside g i l l
Yes
plate)
#92
Day 1 0 Saddletail (i nside g i l l
Yes
plate)
#70
Fish hold (starboard side)
Yes
#30
Fish hold (port s ide)
No (logger lost onboard)
Logger #1 6 was em ployed to m o n itor water tem perature wit h i n the bri ne tank. The
logger was attached to the baffle in the brine tank as seen in Fig u re 5.
Fig ure 5. Temperatu re logger i n brine tank (red tag) .
Tem peratu res were logged throug hout the fis h i n g trip and this data is presented i n
Figure 6 .
17
35.0
J -=- B;i n e tan k d a i l y temperatu re
30.0 -
25.0
6
gi
20.0
!!!
I
Cl
Cl> 1 5.0 f--
:!:!.
!!!
:I
e
�
E
�
-
- - ------ --- -- --- ---
1 0 .0
s.o
- -
.·· · · · ·.
·10.0 �------'
Date and time
Fig u re 6 . Daily temperatu re log of brine tank for all fish ing day.
Very l ittle variation in brine tank tem perature was observed throug hout the fishing
trip. Du ring fish ing days brine temperatu res rarely achieved temperatu res outside
the range of 0-3 'C. However, two notable exceptions are apparent ( see circled
areas in Figure 6) .
The f i rst is the tem peratu re ach ieved during fis h i n g on the 1 ih of Octobe r. The
temperatu re set point appears to have been lowered to around -4 'C for this day,
only to return to previous tem pe ratu re ranges in the ensuing days of fishi n g .
T h e second event is o n the f i s h i n g day o f the 1 8 1h o f October. T h e variation in
temperatu re observed on this day is m uch g reater than any other. Th is observed
effect is cons istent heavy temperatu re load from a large quantity of fish being
loaded i nto the brine. H owever, the temperat u re does not exceed 5 'C at any t i m e ;
a n y c h i l ling capacity appears t o b e coping with the load wel l a s temperatu re
spikes are qu ickly resolved .
Logger #26 and #92 were attached to a Saddletai l snapper and positioned i nside
the gill cavity. The pu rpose of th ese loggers was to m o n itor the external
temperatu re to which the fish were exposed during ch i l l i n g and storage. So the
temperatu re data captu red with these loggers m ore accu rately describe the
conditions to which the fish were exposed rather than the internal tem perat u re of
the fish themselves .
Logger #26 was attached to a Saddletai l o n the second day of fishing
(08/1 0/20 1 0 ) . Th is data is represented i n Fig u re 7.
18
35.0
-------�-- -----
,/ Immersion In brine tank
30.0
1 - Logger #26
"--lf - -------------------------------j
25.0
u
ill
� 20.0
,__,--+------ --------<
I
Cl
Q)
�
Q,) 1 5.0
:;
1U
8_
E
Q)
I-
Transfer to fish hold
1 0.0
---- --- ------ ---- ----- -- --
I
Unload of vessel
5.0 r--t----....--;
6
!);
I)'
0
"'
0
\l
!);
..
6
!);
'!'
0
'!'
0
!);
!);
Date
....
6
!);
6
�
!);
g
F i g u re 7. Tempe ratu re d ata for logger #26 .
The data presented i n Figure 7 shows that this fish has ch i l led q u ickly, and once
transferred to the refrige rated bri ne tank, has mai ntained a temperatu re as low as
-2 "C u ntil u n load . A representation of the first 48 hours of chi l l i n g for logger #26 is
presented in F i g u re 8.
30 0
.......
lmmenlon In brine tank
--
25. 0
u
-
- Logger #26 (fi rst 48h rs)
J
20. 0
rJJ
�
g>
�
e
.a
�
Q)
a.
E
Q)
I-
1 5.0
1 0.0
/ Transfer to fish hold
5.0
0.0
�
\
�
�
- 5. 0 0
0
lJ\�
�
o;
-
�
g
g
0
0
g
Date and time
g
g
A
0
�
0
0
F i g u re 8 . F i rst 48 hours of c h i l l i ng and storage for logger #26.
The Sadd letai l attached to logger #26 is very qu ickly exposed to tem peratu res
below 2 "C wit h i n the fi rst two hours of ch i l l i n g , and then ach ieves tem pe ratu res
below zero. Early the n ext m o rn i n g , the transfer of the fish i nto bins and then i nto
the fish hold resu lts in a small rise i n exposed tem pe ratu re. Howeve r, this qu ickly
reduces back to su b-zero temperatu res wit h i n s ix hours. This tem peratu re profile
is consistent with i ndustry best practice.
19
Logger #92 was attached t o a Saddletail d u r i n g the last day o f fishing
( 1 9/1 0/20 1 0 ) . A g raph ical representation of the data collected from this logger is
prese nted i n Fig u re 9.
30.0 r-------�---,
l- Logger #92
,/ I...... In brine tank
25.0 >--- +----- ------- -- ------- -----<
G'
.,
Q)
�
0)
Q)
:!'?.
�
.;!
�
Q)
Q.
E
20.0 -
Transfer to ftsh hold
1 5.0 r----t--<
1 0.0
- ·- -
-
� - ---- -- -
-
---- -
Unload of vessel
-- - -- -
- - - ------\---
·- .
�
"'
�
�
"'
"'
�
�
�
�
"'
"'
ril
ril
I
"
"
-5.0 G----<:�---0--0---.0.--<>---�0>---<>
"'
0
0
"'
"'
"'
;;;
;;;
"'
o;
8
8
8
8
0
g
g
g
Date and time
g
g
0
Fig u re 9 . Temperatu re d ata fo r logger #92.
The temperatu re profile presented in Fig u re 9 clearly demonstrates that logger
#92 was exposed to su b-zero c h i l l i n g temperatu res almost i m m ed iately afte r
i m m e rsion with the brine tank, and th is sub-zero temperatu re persisted u nt i l
transfer t o the f i s h h o l d . D u ring the transfer process a large tem perature spike i s
observed with the logger ach ieving a m axi m u m tem perature o f 1 4. 0 "C .
This tem perature spike i s an eve nt not u nexpected a s the fish are removed from
the brine tank and packed i nto fish bins specific for each species. As stated
previously, the loggers are attached external to the fish and are m easu ring the
external ambient temperature rather than the internal fish tem perature. So the
spike o bse rved here is consistent with a short exposu re to ambient tem perat u re
prior to t ransfer to the fish hold.
Of a far greater concern is the t i m e taken for the fish to be exposed to adequ ate
ref rigeration tem peratu re once transferred i nto the fish hold. U pon transfer to the
hold su rrou nding tem perature stab i l ises at 9 . 0 "C . However a f u rther 1 2 h o u rs of
ch i l l i n g is req u ired to expose the fish to less then 4 "C, and a further 1 8 h o u rs is
req u i red to ach ieve 0 "C.
Logger #70 was used to monitor hold temperatu re i n the starboard fish hold . The
logge r was placed directly onto fish i n a fish bin and transferred to the starboard
fish hold. The data is represented in Fig u re 1 0 .
20
35. 0 1-----------------:,::;;;::::::;:;
: ;;;:=::::;;;:
:::
:::;:
::
:=;::===-:;;:
-:
:-l
::
- Logger #70 (starboard hold)
30.0 �-------====='.__j
25.0
- 20.0 f--+------------------------·---+----;
()
"'
�
g> 1 5.0 f---tt----+--;
:!!.
�
-; 1 0.0 f---t-----t---;
Q;
c.
::i
E
�
5 . 0 f---+---- -----+---;
-10.0
�-------�
Date
F i g u re 10. Tem perature p rofile fro m starboard fish h o l d .
Logger #70 is exposed to temperature below 4 "C with i n 3 hours i n the fish hold.
Despite a couple of small temperature spikes, slight su b-zero temperatu re is
mai ntained for the du ration of the trip. However, d u ring the last 4 days at sea, the
logger tem peratu re approaches, and for a brief time exceeds -5.0 °C.
Th is occu rrence is not desirable as fish wi l l freeze at this temperatu re. Several
bins of fish were observed as be ing either partly or fully frozen d u ri n g u n load of
this vessel. The i m age below ( Fi g u re 1 1 ) shows a bin of Red Em peror ( Lutjanus
sebae) that were all f rozen solid .
Figure 11. B i n o f frozen red Empero r d u ring u nload .
21
Figu re 1 2 below also shows a bin o f m ixed C o d b e i n g e m ptied i nto a bin o f i c e . All
fish we re frozen sol id .
Fig u re 1 2. B i n o f frozen m ixed Cod frozen together and emptied i nto ice b i n .
These fish went i nto a m ixed bin of fish for transport to a wholesaler. The rest of
the bin was m ade u p of m ostly Sadd letai l s n apper as can be seen i n F i g u re 1 3
below.
F i g u re 1 3. Mixed bin of frozen Cod and Sad d letai l snapper .
22
Manag e m e nt of tou g h fish syndrom e
Alm ost al l of the Saddletai l observed i n this bin were f rozen sol id. Figu re 1 4 below
is a close up of one of these Saddletai l .
F i g u re 1 4. Frozen Sadd leta i l i n m ixed b i n .
Without internal temperatu re m o n itori ng it is difficu lt to determ ine exactly what
temperatu re these fish had achieved d u ring their time i n the fish hold. However,
from the logger u sed d u ring this field trip, a temperatu re of below -5 "C is a d isti nct
possibility.
Some fish transported to Brisbane also showed signs of being exposed to
e levated temperatu res likely to res u lt i n spoilage. Figu re 1 5 below is of a
Saddletai l landed on the 3 rd day of fishing ( 1 1 /1 0/20 1 0) showi ng signs of receiving
tem peratu re abuse at som e stage.
23
S i g n s o f temperatu re abuse include s i n king o f the eye b a l l into the socket and
d iscolou ration of the red colou r i n the skin . This discolou ration is m ost notable on
the dorsal reg ion above the head , the gill plate, and skin of the belly cavity.
Several of the fish transported to Brisbane d isplayed s i m i lar sym ptoms. Th is
discolou ration is caused by sign ificant periods of elevated tem pe ratu re above 4 "C .
G iven that t h i s f i s h was packed i n i c e from the t i m e i t was u n loaded from t h e
vesse l , the cause o f t h i s d iscolou ration is m ost l i kely have been from a hot spot
with i n the fish hold. A sim ilar hot spot was detected by logger #92 ( F i g u re 9 ) .
5 . 1 . 5 . F i e l d T r i p Su m m ary ( FT6)
Sadd letail snapper go i nto rigor faster i n ice slu rry than i n ambie nt temperatu re,
althou g h the d ifferences observed in this work were not statistically s i g n ificant.
Howeve r, when com paring sarcom ere lengths from m uscle fibre with i n the sam e
treatments , there is very l ittle d ifference between any of the resu lts between any of
the treatm ents. The refore the m echanism observed here where colder
temperatu re resu lted i n fast rigor deve lopm e nt is u n l ikely to be a 'cold-shorten i n g '
event a s previously s e e n i n l a n d based animal carcasses like beef ( Bouton e t al.
1 973) .
The resu lts ach ieved for this species appear to be cons istent with those observed
in the work of J errett et al. (2002) who demonstrated that post-m o rtem exposu re
of P i n k snapper ( Pargrus auratus) m u scle tissue to tem peratu res below 6 "C
resu lted i n sharp i ncreases i n m etabolic rate d u e to i ncreased mem brane
perm eab i lity, and a rapid depletion of ATP (adenos i n e triphosphate ) .
A n i ncrease i n the rate o f post m o rtem ATP depletion wou ld hasten t h e
developm e nt o f rigor mortis a s its onset is determ i ned b y the com plete exhaustion
of free m uscle ATP ( Love 1 980) . This m ay be described as a 'cold-shock' as
previously observed by Cu rran et al. ( 1 986) , however this mechanism appears to
resu lt in very l ittl e change in sarcomere length and therefore can not be attributed
to a 'cold-shorte n i n g ' event.
24
Manag em e nt of toug h fish syndro m e
One problem associated with using com mercial practice t o su pply fish f o r t h i s type
of expe rim ent is not being able to determ i n e how long a fish has been in a trap
prior to harvest. Consequ ently, the amount of stress experienced by any g iven fish
is neither know or controllable u nder these conditions. Some of the fish harvested
in t h is work went into rigor with i n 2 hou rs of ch i l l i n g , whereas other did not ach ieve
fu ll rigor wit h i n the 4 hours of assessm ent.
A sign ificant resu lt may have been ach ieved by using live and rested fish prior to
euthanasia and i m m ersion with i n the d iffe rent ch i l l i n g temperatu res . This would
m i n i m ise the potential for large variation observed with in each of the treatments
with regard to the time taken for the onset of rigor.
The resu lts obtai ned from the temperatu re logge rs have proved usefu l , even
thou g h two of the loggers were lost or destroyed du ring the field trip. Som e of
these resu lts are encou rag i n g and some are less than satisfactory.
The perform ance of the brine tank was an encou rag i n g res u lt. Th is vessel and this
brine tank h ave been the subject of a previous field trip (Octobe r 2008). Du ring
this trip, temperatu re logging demonstrated the refrigeration system used i n the
brine tank would struggle to maintain temperatu re u nder heavy load from large
n u m bers of fish.
D u ri n g the field trip of October 2008, brine tank tem perature rose to values over
5 "C on six separate occasions of heavy load due to large n u m bers of fish being
landed . D u ring this trip, the h i g h est tem perat u re ach ieved u nder load of fish was
4 "C and this was only achieved once.
Of g reate r concern was the large variation i n ch i l l i n g efficiency observed wit h i n the
fish holds . The two fish logged during this work provide vastly diffe rent resu lts .
Logger #26 (Figu re 8) was attached to a Saddletai l on the second day of fishing
and the resu lts presented i n demonstrates ch i l l i ng presented i n the early days of
fish ing is of a standard equ ivalent to i ndustry best practice. However, logger #92
(Figure 9) demonstrates that the ch i l l i n g efficiency observed from logger#26 is not
consistent throug hout the fish holds. This m ay be d u e to i neffective insu lation ,
i neffective c h i l led a i r circu lation , or a com bi nation o f both these and other
influences yet to be determ ined.
Logger #70 ( F i g u re 1 0) also clearly shows that fish hold tempe ratu res can
descend below -5 . 0 "C and provides clear evidence to explain why so m any fish
were u n l oaded f rom the vessel f u l ly f roze n . Freezing fish i n this temperat u re range
resu lts in decreased shelf-l ife when thawed, increased drip loss when filleted and
i nferior product quality generally as the slow freez ing produces large ice crystal
with i n the fish m uscle, maximising the damage to the m u scle tissue. This is
particu larly relevant for h i g h value species such as Red em peror ( Lutjanus sebae)
and Coral trout ( Plectropomus spp) .
25
5.2.
Analysis of TFS across years and seasons
5 . 2 . 1 . Sample C o l lection
I nput was soug ht from stakeholders i n all th ree fish ing m ethods i n the sector being
trap, line and demersal trawl . It was envisaged samples wou ld be sought from all
3 fishing m ethods. However, this proved problematic due to lim ited access to
su itable on board freezing capacity o n several of the vessels supplying fish for this
proj ect.
Onboard-freezing of fish h as been an essential part of the sam ple col lection
process due to resu lts obtained after the i n itial field trip for FRDC project 2008/208
in November of 2009 ( Forrest et al. 20 1 0) . The resu lts from this work suggested
post-mortem changes in m uscle chem istry associated with endogenous enzym e
activity during cold storage exh ibit an effect o n cooked m uscle texture.
I n short , m uscle texture was d i rectly affected by time spent cold storage.
Endogenous protease and collagenase activity in situ conti n u ed during cold
storage and g reatly influenced text u re analysis res u lts . Freezing o n fish onboard
was thus deemed essential in obtai n i n g sam ples that were subject to as l ittl e post
mortem enzym atic activity as possible.
With this issue i n m i nd it was dete rm in ed that o n l y one vessel was capable of
providi n g sufficient n u m bers of Saddletail at poi nt of capture , and also h ad
sufficient freezer capability to rapidly freeze and store whole frozen fish on board .
A s u m m ary of the field trips is presented i n Table 7.
.
Ta bl e 7 S u mmarv o f f1e Id trips.
Tria l name
Date of sample col lection
Nu mber of fish (n=504)
FT2
Nov/Dec 2 0 08
111
FT3
Apr/May 2009
1 01
FT5
Nov 2009
1 09
FT?
Dec 2 0 1 0
1 00
FT8
Apr/M ay 2 0 1 1
83
5 . 2 . 2 . Text u re data for a l l trips
Textu re data for all trips is best presented in a frequ e ncy h i stog ram . Th is
histogram is prese nted in Fig u re 1 6.
26
Manag e m e nt of tough fish syndrom e
1 80 -,-----,
(N=504)
1 60 +---------1 40 +-------<
120
g 1 00 +-------===---!
.,
::I
C"
�
u.
80 +--�----�
60 -
- --
40 +-------1
21
10
20
30
40
50
60
70
80
90
1 00
1 10
1 20
1 30
> 1 30
Texture category (mJ/g)
F i g u re 1 6. Freq uency h i stog ram of textu re data fo r all fish (FT2 to FT8) . .
From t h i s h istogram above, over 70% o f a l l f i s h m easu red have a work d o n e (W O)
valu e between 30mJ/g and 60mJ/g . This texture range is acceptable by the
majority of consumers assessed during a formal taste panel (Chapter 5.4) . Fish
presenting WO val u es above this th reshold represent those m ost at risk of being
rejected by consumers .
5 . 2 . 3 . Analysis of resu lts by field trip
Sign ificant differences were fou nd i n alm ost all m easu red param eters across all
field trips. A s u m m ary of resu lts is presented in Table 8.
Ta bl e 8 . S u mmarv o mean resu I ts f or b ot h sexes o f sa d d l eta1· 1 snapper.
Field t r i p
Parameter
WO (mJ/g)
pH ( u ltimate)
WT (g)
FL (cm)
Sig.
FT2
FT3
FT5
FT?
FT8
(n=1 1 1 )
(n=1 0 1 )
( n = 1 09)
(n=99)
( n=83)
53. 1 3u
60.63a
46.52c
5 1 .44u
54. 67°
( 1 .494)
( 1 .749)
( 1 .508)
( 1 .574)
( 1 . 728)
6 .38°
6 . 43°
6 .56a
6 .32e
6 .35°
(0.01 1 )
{0 .0 1 2)
(0.01 1 )
{0.01 1 )
(0. 0 1 3)
1 88 6 f
2000 .4u
1 530 .7u
1 842 . 5°
23 1 8 .9a
(36. 65)
(42 .9 1 )
{36.99)
(38 .6 1 )
(42 . 39)
5 0 . 28c
5 1 .70°
47.05e
49.40°
54.46a
(0.34)
(0.40)
(0.35)
(0 .36)
(0 .40)
p<0 . 0 0 1
p<0 . 00 1
p<0 . 0 0 1
p<0 . 0 0 1
Means followed by a different letter are s1gn1f1cantly different at the stated level.
Standard errors are shown in brackets.
27
Although signif icant differences exist between the m ean valu es o f the f ive sets of
sam ples , trends consistent across all fou r param eters m easu red are less obviou s .
S i z e and wei g ht differences are h i g h ly i nf l u enced b y t h e ratio of m ales t o females,
as m ales are sign ificantly larger than females of the sam e age ( Forrest et al.
20 1 0) . D ifferences i n work done wil l also be strongly influenced by the age of the
fis h , wh ich is not taken into accou nt i n t h is analysis.
The s i g n ificant d ifferences i n f inal m uscle pH are resu lts worthy of further
com m e nt. Final m u scle pH is strongly i nfluenced by the m u scle g lycogen present
wit h i n fish m uscle at the time of death ( Love 1 980). At the time of death, m uscle
glycoge n conti nues to be m etabol ised via an anaerobic pathway to u ltim ately
produce lactic acid. High l evels of avai lable g lycogen result i n lower fi nal pH. The
iarg e d ifferences observed i n finai m uscie pH betwee n the FT5 and both FT7 and
FT8 suggests the h ealth and condition of the fish sam pled varied g reatly between
individuals. Whether this is a resu lt of seasonal activity such as rainfall , or an
artefact of the trawl shot at the t i m e is difficu lt to ascertain with confidence . FT5
also had the smallest fish of all trips and this may influ ence the pH res u lt.
5 . 2 .4 . An alysis o f resu lts b y trip and sex
Fu rther understanding of the trends is gai ned u pon exam ination of the trends
across the field trip by sex. A s u m m ary of these resu lts is presented in Table 9 .
.
Ta bl e 9 S u m mary o f f1e Id t np d at a f o r ma e an d f ema I e S ad d l et a1· 1 snaooer
Male
Parameter
Female
WO (mJ/g)
Sig.
FT2
FT3
FT5
FT?
FT8
FT2
FT3
FT5
FT?
FT8
n=57
n=42
n=56
n=64
n=25
n=54
n=39
n=53
n=36
n=58
57.36"
58. 29au
47. 46c
5 1 . 27c
62. 76a
48. 66c
63. 1 4a
45. 53"
5 1 . 73c
51 . 1 8c
(2.05)
(2.39)
(2.07)
( 1 . 94)
(3. 1 0)
(2. 1 1 )
(2.48)
(2. 1 3)
(2.58)
(2. 03)
(ultimate)
6.346
6.4 1 u
6. 54u
6.31
6.346
6.4 1 u
6. 46"
6.57"
6 . 326
6. 356
( 0 . 0 1 5)
(0. 0 1 7)
(0. 0 1 5)
( 0 . 0 1 4)
(0. 023)
(0.01 5)
(0. 0 1 8)
(0. 0 1 5)
(0. 0 1 8)
(0. 0 1 5)
(g)
1 806u
1 6996
1 40 1
1 6 1 26
1 965"
1 97 1 "
2324u
1 6676
2250u
2471 a
(41 . 7)
(48.58)
(42.07)
(39.35)
(62.97)
(42.84)
(50.41 )
(43. 25)
(52.47)
(4 1 .34)
49.396
49. 236
45.439
47.30
5 1 . 48°
51 . 22°
54.37°
48. 776
53. 1 4c
55_ 75•
(0.39)
(0.46)
(0.40)
(0. 37)
(0 . 60)
(0.40)
(0.48)
(0.41 )
(0.50)
(0.39)
pH
WT
FL (cm)
P<0. 001
p<0. 001
p<0. 001
p<0. 001
Means followed by a different letter are significantly different at the stated level.
Standard errors are shown in brackets.
Sign ificant differences exist i n all parameters measu red both between trips and
between m al e and female Saddletail snapper. These d ifferences are more
appare nt when the resu lts are expressed g raph ical ly. This can be seen i n Fig u re
1 7 through to Figure 20.
28
�
.s
"'
c: 55
0
.,,
""'
0
:::
50
45
40
FT2
FT3
FT5
FT7
FTB
Field trip
F i g u re 1 7. Mean work done values fo r male and female Sadd letai l snapper .
( Standard error bars are shown)
FT2
FT3
FT5
FT7
FTB
Field trip
Figure 1 8. Mean muscle pH (ultimate) fo r male and female Sadd letail snapper .
29
2400
.!:!!
� 1 800
�
1 600
1 400
1 200
1 000
2F
3F
SF
7F
BF
Field trip
F i g u re 1 9. Mean fish weight for male and fema le Sad d l etai l snapper .
FT2
FT3
FTS
FT?
FTB
Field trip
F i g u re 20. Mean fork length for male and female Sadd l etai l s napper.
For female Saddletai l , fish size correlates reasonably wel l to work done. The same
can not be said for male Saddletail . D ifferences i n m ean pH val ues are h i g h ly
significant, however there is no obvious relationship to other param eters.
30
5 . 2 . 5 . Analysis of resu lts by esti matio n of fish age
Age o f f i s h h as previously been identified a s a sig n ificant d river o f toughness i n
cooked Saddletail s n apper f l e s h ( Forrest e t al. 20 1 0) . F i s h a g e estimation was
com pleted by otol ith section for Saddletail from FT3 and FT5 with the ass istance
of Fisheries Queensland ( Fisheries-Queensland 2009) . Further access to otolith
section age determ i n ation becam e problem atic due to time and budget
constraints . As such, an alte rnative m ethod of age determ i n ation was sought.
Age determ i n ation by otol ith weight has been attem pted on m any species around
the world (Cardinale et al. 200 0 ; Fletcher 1 99 1 ). Closer to home, otol ith weight
has been em ployed as a tool for age estimation on sign ificant com m e rcial species
such as com mon coral t rout ( Plectropomus leopardus) by Lou et al (2005) .
The age data col lected from FT3 and FT5 (n=2 1 0) was used to develop a
pred ictive ( l i n ear) m odel that would assist i n providing an est i m ate of fish age from
otolith weight. The model is presented in Fig u re 2 1 .
2.5 �--y
=
0.0631 x
+
0.4534
R' : 0.91 04
•
2.0
§
.E
1 .5
Cl
·�
·"'
0
.<:
5
1 .0
0.0 +-------<
10
15
20
25
Fish age by otol ith increment (yrs)
Figure 21 . Relationsh i p ( l i near) between fish age and oto lith weig ht for all Saddletail
snapper collected d u ri ng FT3 and FT5 (n=21 0).
Fish age for Saddletail collected during FT? and FT8 was estim ated using form ula
p resented i n Figure 2 1 . The m ean weight of both left and right otol iths was used to
ach ieve this. No otoliths were collected during FT2 so no age estimation of these
fish was possible.
Using the predictive model age data and otolith section ages (n=373) , a sig n ificant
exponential relationship (p<0 .00 1 ) between estim ated fish age and work done
describing 45. 5% of the observed variation. This relationship is presented in
Fig u re 22.
31
1 20
•
[• All fish (FT3 to FT8)
•
•
�
§.
80
0
5:
60
..
c
0
'O
""'
- - �
•
•
-
•
_.
•
•
••
•
••
�""""--=-"
-··�--.___ __ _ _ _ __
•
10
.,
•
15
.
25
20
30
Estimated age (yrs)
Fig u re 22. Est i mated age and work d o ne for all fish fro m FT3 to FT8 ( n=373) .
When the age data is broken into the separate field trips , exponential reg ression
reveals a sig nificant relations h i p ( p<0 . 00 1 ) between fish age and work done,
explai n i ng 53. 1 % of observed variatio n . This relationship is presented in Fig u re
23 .
10
15
Estimated age (yrs)
20
25
30
2
2
2
F i g u re 23. Estimated age and work d o ne for FT3 ( r =0.65), FTS (r =0.47), FT7 ( r :0.27)
2
and FT8 (r =0.57).
D ifferences appear to exist between the trend l ines of the trips . However these
differences are not s i g n ificant . The observed d iffe rences become l ess noticeable
as the data is presented by sex as wel l as trip.
32
Manag e m e nt of tough fish syndrome
Exponential reg ression with g ro u ps (sex and trip) reveals a sig n ificant relationship
(p<0 .00 1 ) between fish age and work done explai n i ng 57. 1 % of observed
variatio n . Th is resu lt is p rese nted g raph ically in Figure 24 and a su m m ary of the r2
val u es from this analysis is prese nted i n Table 1 0 .
1 40
1 20
]
FT3
FT3
"' FT5
x FT5
:!: FT?
• FT?
+ FT8
I
I - FT8
1 00
Ci
"'
80
..
c
0
'O
""
60
§.
0
3::
•
•
•
(female)
(male)
(female)
'
(male)
(female)
(male)
(female) i
(male) ,
•
+
;!:
�
40
;!:
•
20
15
10
20
25
30
Estimated age (yrs)
Figure 24. Esti mated age and work done fo r all trips and both sexes.
Ta bl e 1 0 S u mmary o f r2 va ues f rom F1 g u re 24
Field tri p
"
female r val ues
"
male r vales
FT3
0 . 67
0 . 68
FT5
0 . 50
0 . 42
FT?
0.30
0 . 22
FT8
0 . 64
0 . 52
Althoug h some d ifferences are apparent between the sexes and field trips, the
d ifferences are not s i g n ificant. For exam ple, the male fish from FT3 exh i bit m u ch
more f i rm n ess than the m ales of FT8. However, the female Saddletail f rom FT3
and FT8 exh ibit alm ost identical trend l i n e with good r2 val u es (bei ng 0 .67 and
0 . 64 respectively) .
When the relationship between sex and texture is exam i ned the data sets are
even closer. Exponential reg ression with g ro u ps (sex) reveals a sign ificant
relationship ( P<0 . 00 1 ) between fish age and work done explaining 45 . 6% of
observed variatio n . Th is relationship is presented in Figu re 25.
33
1 40
• all
•
males all trips
all female all trips
•
•
•
1 20
•
1 00
•
Ci
""
E
Q)
c:
0
"C
.><
0
3:
80
..
•• • •
•
•
•
•
�
1•
# .it -• 1 · tI
•
•
•
. •+
'- ir
•
•
••
•
•
• •
•
•
•
•
•
•
60
40
•
I
•
• •
• ••
I '•- • -.--
20
10
15
20
25
30
Estimated age (yrs)
ip
2
F u re 25. Estimated age and work done (al l trips) fo r all female (r :0.51 ) and male
(r :0.42) Sadd leta i l snapper.
The s i m i larity between the trend l i n es of male and fem ale fish across all fou r field
trips suggest other d ifferences previously observed betwee n trips m ay i n fact be a
trip effect. I n other words , the data from any individual trip appears to be
som ewhat skewed by the g ro u p of fish sam pled d u ring that trip. The m uch larger
n u m ber of fish represented by the data i n Fig u re 25 (being 1 87 females and 1 86
m al es) provide a sou nder basis for analysis as the trip effect is eve n ed out ove r
the fou r field trips.
When the resu lts are exam ined by season a very sim ilar trend is observed .
Exponential regression with g roups (seaso n) reveals a sign ificant relationship
(p<0 .00 1 ) betwee n estimated age and work done explain i ng 45.3% of observed
variatio n . This resu lt is presented in Fig u re 26.
34
1 40
• All fish (autu m n )
• All f i s h (spring)
•
•
1 20
•
•
1 00
�
80
.,
c:
0
"C
-"'
60
§.
0
:;::
•
•
•
•
•
40
20
10
15
20
25
30
Estimated age (yrs)
Figure 26. Estimated age and work done (all trips) fo r Sad d l etail snapper landed in
2
2
autumn (r =0.47) and spri ng ( r =0.49).
There is very l ittle d ifference between the data sets prese nted in Fig u re 26.
Exclusion of the outlyi ng values above 1 OOmJ/g resu lts in near identical trend l i nes
and the variation explained increases to 48. 1 %.
As with the previous exam ination of the data by sex, exam i n i ng the data set by
season alone appears to reduce the influence of individual trips to skew the
resu lts. From the res u lt prese nted i n Fig u re 26 there appears to be no seasonal
i nfluence on flesh texture at a l l .
35
5 . 2 . 6 . Su m m ary of age , season a n d text u re analysis
T h e pri m ary g o a l o f this part o f the proj ect was t o exam ine the influence of
seasonal and geograph ical factors that m ay influence tou g h n ess in Saddletail
snapper.
Geog raphical data was not presented i n t h is m ilestone due to com m e rcial
considerations. Originally, fish were to be sou rced from a trap m ethod as we ll as a
trawl vessel. However, the trap vessels operating i n this fishery had i nsufficient
freezer capacity to handle the large num bers of sam ples required .
As a result, all samples provided for this section of the research were provided by
the single trawl vessel operating in NT waters at the time. As such, in view of the
fishery moving to quota, as wel l as new stakeholders com i ng i nto the fishery, the
autho rs deemed the g eog raphic location data as highly com mercially sensitive
and not su itable for publ ication i n this report.
Seasonal influences have been considered by other researchers as a possible
explanation for variation i n cooked textu re ( Hagen et al. 2007; Ito et al. 1 992) .
Additional data col lected d u ring subseq u e nt seasons has al lowed us to com pare
fou r years of data. Analysis of this data has dem onstrated that any seasonal effect
previously observed, beco m es less relevant over the fou r years exam ined.
Howeve r, as we have reported ( Forrest et al. 20 1 0) , the prim ary driver of
toug h ness in cooked Saddl etail snapper is fish age . And although fish age has
been estimated from otolith weight for two of the fou r trips rather than trad itional
otolith section i n g , the resu lts prese nted here i l l u strate a highly sig n ificant
correlation between fish age and flesh firm ness.
36
5.3. Current applications of sensing or imaging technology
in fish biology
This section is a s u m m ary of cu rrently available tech nology su itable to assist
stakeholders i n removing Saddletai l at risk of developing TFS f rom their catch .
Identifyi ng fish age non-i nvasive ly wou l d b e the perfect appl ication . H owever, this
is not cu rrently achievable with cu rrently avai lable technologies. The next best
selection tool wou ld be identifyi ng the sex of Sadd letai l snapper non-invas ively.
Th is wou ld at least supply stakeholders to use cu rrently avai lable fork length data
for each gender, as male fish are sign ificantly larger than female fish of the same
age .
Su m mary of available tech nolog ies
Two forms of tech nology are cu rrently being used for determ ination of fish sex.
These are u ltrasound sonog raphy, and near i nfra- red spectroscopy ( N I RS ) . They
each have their own advantages and disadvantages.
Opt i o n 1 : Ultrasound i mag i ng :
Advantag e : Mach i nes are easily obtainable from seve ral suppl iers.
Disadvantage : Req u i re sign ificant levels of expertise to operate and identify sex
organs.
Opt i o n 2: Near i nfra-red s pectroscopy ( N I RS) :
Advantage : Requ i res m i n i m al trai n i n g once a model has been developed .
Disadvantage : Sig n ificant expertise is req u i red to develop p redictive model and
machines are m o re expens ive, and req u i re sign ificant u nderstanding to setu p .
A more detai led explanation o f each o f t h e tech nologies fol lows .
37
5 . 3 . 1 . U ltrasou nd i mag ing
U ltrasou nd technology f o r m ed ical appl ications emerg ed from t h e large i nvestment
in sonar tech nology during WW I I . Researchers i n Sweden, Scotland and the U SA
began developing m ed ical applications du ring the late 1 940's and early 1 950's.
Modern diagnostic u ltrasou nd sonog raphy operates between the frequ encies of 2
to 1 8 m egahertz ( M H z ) .
P u t sim ply, higher f requ encies produce higher resolution images, however t h e
higher t h e frequ ency the less penetration t h r o u g h tissue. Superficial structu res
close to the ski n are scanned in the range of 7- 1 6 MHz. Deeper tissue such as
kidney requ i res lower frequencies in the region of 1 -6MHz.
Fig u re 27. T h e H itac h i Aloka SSD-500V portable co nvex sector/l i near u ltrasound
scanner commonly u sed i n small a n i ma l appl ications.
More recently, this tech nology has been trialled o n several fish species for various
pu rposes. The m ost common application is to non-i nvasively determ i n e sex at
sexual matu rity for l ive fish. This technology has been successfully applied to
Striped bass ( Blythe et al. 1 994 ), Atlantic cod ( Davie et al. 2003 ; McEvoy et al.
2009) , Atlantic halibut ( Robichaud et al. 1 998) and African catfish (Anchionye
Nzeh and J i m o h 20 1 0) . U ltrasou nd has also been uti l ised to identify Atlantic
sal mon suffe ring from previously u ndiag nosed cardiomyopathy (Sande and Poppe
1 995) . In Australia this technology has been applied to Mu rray cod ( N ewman et al.
2008) .
38
Central to the use of this tech nology, is the abi l ity to observe cross-sectional views
of i nternal organs. I n most fish species, there is a s i g n ificant d ifference i n size and
structure between male and female gonads.
However, using the scan ner req u i res s i g n ificant trai n i ng to operate successf u l ly,
and u nderstand i n g of not only the m echanism of the scan ner, but the anatomy of
the fish species being observed . Th is is the s i n g l e m ost l i m iting factor preventing
the use of this technology. Extensive knowledge of fish anatomy wi ll be i ntrinsic to
the success of im plementing this kind of technology.
In Australia, suppliers of equ i pm ent who provide trai n i ng as we l l are difficu lt to
find. The most prom i nent s u pplier of equ i p m ent su itable for small an imal
applications is BCF U ltrasound Austral ia. They su pply m achines su itable for small
an i m al use and conduct trai n i ng sem i n ars i n Australia and New Zealand.
Pricing for an u ltrasound scan ner of this nature wou ld be just u nder $ 1 OK for
new m ach i n e , and somewhere around $5K for a second hand u n it.
a
Potential s u p p l i e r deta i l s :
BCF U ltrasound Australasia Pty Ltd
U n it 1 0/56 Norcal Road
N u nawad ing 3 1 3 1 Victoria
Australia
t : +61 3 9894 8980 f : +61 3 9894 899 1
Sales : sales@bcfu ltrasound.com
Service : service@bcfu ltrasound.com
Acco u nts : m arie@bcf u ltrasound .com
39
5 . 3 . 2 . N e a r i nfra-red spectro scopy ( N I RS)
Near i nfrared spectroscopy (NI RS) has been util ised to develop non-invasive
m ethods of determ i n i ng various param eters of food quality, particu larly in
horticulture produce. Non-invasive determ ination of fat content in avocado is a
we l l studied m ethodology i n Austral ia (Wedd ing 2009 ; Wedd ing et al. 2 0 1 0 ) .
Howeve r, u n l ike the u ltrasou nd device that creates a cross sectioned i m age of the
internals of the fish , N I RS rel i es u pon the successf u l development of a pred ictive
model to allow determ i nations to be m ade. The model is developed by scan n i ng
the obj ect i n question with a beam of N I R frequencies in the range of
approximately 700 nm to 1 1 OOnm and recording the leve ls to which these
frequencies are reflected off the target and back to the sensor. It is these
responses to the N I R frequ e ncy range and use of powerfu l statistical analysis
software that perm it the developm ent of a pred ictive m odel.
Th is m odel can be made on as l ittle and 1 00 repl icates. However, g reater
accu racy req u i res m any m o re repl icates, and n u m bers approaching 1 000
replicates are com mon attained when developing a model.
Once a model has been developed , the N I RS can be connected to a computer for
record i n g of resu lts and a sim ple yes/no (male/female) determ ination is provided
by the com puter. This tech nology g reatly reduces the reliance subj ective
observations by the operator and thus g reatly reducing the error rate, and speed
at which determ i n ations can be m ade. This technology also lends itself we ll to be
i nteg rated withi n automated processing systems.
F i g u re 2 8 . A n i mage fro m Davis e t a l (2006) showing the u s e o f t h e SW-NI RS d evice
on a C h i nook salmon.
A recent u ndergradu ate study at Oregon State U n iversity has demonstrated short
wave N I RS (700- 1 1 OOnm) can be used to identify the sex of m ature Ch inook
salmon with a very high degree of accu racy (Davis et al. 2006) . Although there is
40
l ittle i n the way o f f u rther studies on other species, i t is h i g h ly l i kely that this
m ethodology wi l l be appl icable to m ost fish species of s i m i lar body size.
The use of this device also req u i res a reasonable amou nt of trai ning to operate.
And agai n , a sou nd knowledge of the anatomy of the fish is again essential .
Developm ent of the predictive model is the m ost com plicated stage of i ntroducing
this tech nology. Many hou rs of repl icate sam pling is req u i red, as well as a
thoro u g h u nderstanding of phys ics , mathematics , and statistical analysis tools.
This is probably the single major drawback preventing
Costs of N I RS devices usually start aro u nd the $ 1 OK m ark for a hand-held device.
Portable m achi nes are available for rem ote use. Howeve r, m odel development is
best done in the laboratory enviro n m e nt to create standard conditions.
5 . 3 . 3 . Potential su p p l i e r detai ls :
Brett Treacy
Bret-Tech I B rett's E lectrical
1 0 Blackal l Street,
Woom bye Old 4559
T (07) 5442 3766 Bret-Tech
T (07) 5442 3722 Brett's E lectrical
F (07) 5442 3076
Emai l : brett@bret-tech .com .au
Web: www.bret-tech . com . au
41
Managem ent of toug h fish syndro m e
5.4.
Consumer
assessment
of
Saddletail
Threshold of rejection with regard to texture.
texture:
5 . 4 . 1 . Resu lts
Com plete assessments were obtained from 53 pan e l lists. Prior to evaluation of the
fish samples, panellists were asked some questions regarding their buying
frequency as seafood preferences.
Questio n 1 asked the pan e l l ists to pick an age category that best described them .
This qu estion is asked to ensure the panell ists represent a good cross-section of
f'.
,..,
,.. _ ,..
__
,
;
n
;
;
i Q I VVV
_, 1 r"" h "' l"" o r roT h o C' o r n c- 1 dtc- -:i rn n r o c- o nt.a� i n J:' i r11 1 ro 'JO
tJ U I Vl l U U V I U o l l l V •,;H.., I V U U I L..., � · - t-' ' '"' "'"' "" ' ' LV """' 1 1 1 1 1 � \,.11 1 ..., - "" •
<31 yrs
3 1 -40 yrs
4 1 -50 yrs
5 1 -60 yrs
>60 yrs
F i g u re 29 . Age categories of consumer pane l l i sts.
The age distribution of panel l ists in Fig u re 29 is consistent with the distribution of
seafood consu m e rs in Austral ia ( Ruello 2006). Almost 70% of panell ists described
themselves as age 41 years or greater. This age g ro u p contains the vast m aj ority
of seafood consu m e rs in Australia.
Question 2 asked how ofte n they pu rchased the g roceries i n the household.
Pan e l lists were asked how often they purchased the g roceries i n their household.
These resu lts are presented i n F i g u re 30.
42
�
c
Cl>
::I
20 +-----1
18
i
LL 1 s
+-----1
Share the p u rchase
Alm ost always
Almost never
F i g u re 30. Seafood purchase frequency of panel l i sts .
The resu lts in Figure 30 demonstrate that the majority of panellists (47 of 53) we re
i nvolved i n g rocery purchase. This resu lt demonstrates our consu m e rs are
regu l arly i nvolved in the pu rchase of food for their households.
Question 3 asked them how often they pu rchased fresh or frozen seafood . These
resu lts are prese nted in Fig u re 3 1 .
40
37
35
30
,.,
0
c
�
C"
l!!
25
20
u.
15
10
Several times a week
About once a week
About ante a month
About once every 3
months
Only at Christmas or
Easter
Figure 31 . Seafood pu rchase frequency of panell ists .
Question 4 asked pane l l ists to name the t h ree m ost com m only pu rchased seafood
products. A total of 1 38 responses were received . These resu lts are presented i n
43
Manag e m e nt of toug h fish syndrome
37
pJawns
salmon
fresh lish
calamari
barramundi
snapper
whiting
"'"
fresh tuna
scallops
nile perch
bassa
do<y
hok;
oysters
shark
mackerel
sweetHp
goldband snapper
red snapper
bream
mussels
on special
coral trout
mullet
5
0
10
15
20
Frequency
25
30
35
40
Fig u re 32. Commo n l y p u rchased seafood products for pane l l i sts ( n = 1 38) .
Resu lts from this question demonstrate are large variety of seafood products
consu m ed by the panel l ists. Howeve r, the most com m o n ly pu rchased products
(prawns and sal m o n ) represent almost half of all responses (44% ) . The next
highest individual product nam ed is fresh fish. All responses that could be
i ncluded as fresh fish ( i ncluding specifically nam ed species) represent 60
responses or 43% of all responses. From this res u lt we can confirm our pane l lists
are representative of seafood consu mers of the seafood category (fresh fish) that
Saddletail s napper are most appl icable to.
Question 5 was the prim ary assessment qu estion for textu re acceptabi l ity. These
resu lts are presented in Table 1 1 .
Ta b l e 1 1 Resu ts summary f rom consumer acceptabT
1 1tv assessment.
Texture Category
Mean text u re (mJ/g)
% Acceptabil ity (n=53)
1
37.58 (±1 .82)
1 00
2
49.66 (±0.99)
94 . 3
3
59.40 (±2 .83)
88.6
4
7 1 . 9 8 (±2 .5 1 )
79.2
These resu lts show are clear trend of reducing acceptabil ity with an increase in
texture val ue as determ i n ed by l nstron m easu rement (mJ/g) . H owever, the
toughest samples sti l l received an overall 79 . 25% acceptance ; wh ich is well above
the dete rm i ned threshold of rejection of 50%.
Question 6 asked pan e l lists to provide com m ents o n any particu lar aspect of the
sam ple that they l iked . Qu estio n 7 asked panellists to provide com m ent on any
aspect of the sam ple that they disliked. These com m ents can be found i n fu l l in
Appendix 2 . Com ments range from those about, flavo u r, text u re, aftertaste, colour,
odour, and comparisons with other seafood products . A large portion of these
com m e nts were reserved for texture, both l i ke and disl ike com m e nts . A s u m m ary
of the n u m ber of l i ke com m ents can be found in Tabl e 1 2.
44
.
Ta bl e 1 2 S u mmarV O f l 1"ke com ments re I atmQ
to texture.
Total l i ke
Text u re
L i ke comments for
% of total
catego ry
comments
texture
comments
1 (38mJ/g)
51
29
56.9
2 (49mJ/g )
49
29
59.2
3 (49mJ/g)
36
13
36 . 1
4 (72mJ/g)
43
10
23.3
The resu lts from this question demonstrate a trend of decreasing ' l i ke' com m e nts
regard i n g text u re in accord with i ncreasing textu re val u e . The m ajority of
responses for both category 1 and 2 com m e nts related to texture. I nterestingly, 1 0
of the 43 com m e nts for category 4 fish samples were sti l l describing aspects of
the text u re that were desi rable .
Question 7 asked f o r responses t o anything that was disliked i n a n y o f the
sam ples. A s u m m ary of the resu lts that related to text u re are presented i n Table
1 3.
T a bl e 1 3 S u m marv o f d"1s l "1 k e commen s re I af mQ to textu re.
Total d i s l i ke
Dislike comments
Textu re
% of total
catego ry
comments
for text u re
comments
1 (38 mJ/g)
20
5
25.0
2 (49 mJ/g)
25
6
24 . 0
3 (49mJ/g)
25
7
28.0
4 (72mJ/g)
36
24
66.7
The first observation from this data is disl ike com m e nts were reported i n m uch
fewer n u m bers than l ike com m e nts. The trend of total dislike com ments made is
also the i nverse of those seen for l i ke comm ents.
However, the most important result from this question is the n u m ber of dislike
com m e nts relating to textu re (24) as a proportion of the total n u m ber of dislike
com m e nts (36) for toughest samples (category 4) . Over 66% of dislike response
for this sam ple related to texture that was not des i rable. Th is res u lt suggests that
the samples consumed by these panellists were very close to the point at which
the text u re cou ld be deemed to be u nacceptable.
5 . 4 .2 . D i scussion
T h e resu lts f rom the consumer acceptabi lity assessment provided no clear
th reshold of consumer rejection of cooked Saddletai l texture. Howeve r, with
fu rther exam i n ation of the dislike com m e nts provided by panell ists, two th i rds of
dislike comm ents for sam ples from category 4 (66.7%) m entioned texture as at
com ponent of what they didn't l i ke about that sam ple. So although consum ers
wou l d not rej ect the sam ple presented to them i n the acceptabi l ity assessment,
the f i rm n ess of textu re was a factor that was perceived by the consu m e rs and
described by the majority of respondents as an attribute that they did not l ike.
45
Th is result brings i nto question the choice o f a forced binary assessm ent rather
than the use of h edonic or category scales. However, u ntrai ned sensory pan e l l ists
such as these are well-known to be hesitant in utilising the full range of selection
available to them in such assessments. This behaviour is prim arily d riven by a fear
of being wrong and being called to accou nt. In this case, presenting a forced
accept/reject question to cons u m e rs m ay have been somewh at intim idating to
som e pane ll ists and they have avo ided providi n g a rej ection answer in case they
are wro n g .
T h i s m ay also be a result o f their u nderstanding o f the product itself. O f the 1 38
responses to fish names, o n l y one response used the term red snapper. And no
pane l list used the term Saddletail. For m any pan e l lists this may have been the first
time they have ever tasted Saddletai l snapper. And when presented with new food
products cons u m e rs can often teel contused as to what it is they are actuaiiy
tast i n g . I n such an enviro n m e nt, aski ng a consumer to reject the product m ay be
asking too much as they are not confident they know enough about what they are
eating.
Using a category o r hedonic scale m ay h ave provided consum e rs with m o re
confidence to provide slightly more negative feedback without going to the point of
al l out rejectio n . However, scaled m easu res are best e m ployed when panel l ists
can be t rained to u nderstand the l i m its of the scales they are u s i n g . Without such
trai n i n g , panellists invariably use very l ittle of the scale making d iscri m ination
between sam ples somet i m es difficu lt, and more often i m possible.
Another factor which m ay have played a rol e is the s ize of the sam ples assessed
by the consum ers. Portions were cut i nto 2cm by 2cm squ ares, which can s i m ply
be described as bite size portions. This is done for two reasons. Firstly, to
standardize the sam ples as m uch as possible. But also , to ensure panell ists do
not consume too m u ch of the product as m eat, and particu larly fish, has a
significant satiety effect. I n othe r words, fish can m ake you feel 'fu l l ' even afte r
consu m i ng relatively small amou nts. Asking panell ists to taste food when they are
'fu l l ' is not good practice as their responses wi l l be influenced by this feel ing .
Presenti ng panell ists with a whole cooked f i llet of Saddletail m ay have produced
qu ite different resu lts. Asking pan e l lists to cut a portion off a whole fillet m ay have
provided them with a better understanding of how a fillet m ay appear when it
presents with toug h ness . This pri m arily the m ethod m ost consumers of beef wou l d
u s e t o assess the texture o f a steak o f beef either a t home o r i n a restau rant.
However, this is not standard practice i n the vast m ajority of meat assessm ent
involvi n g consum ers with i n the l iterature. Also, the log istics and resou rces
i nvolved wou ld be far g reater than those avai lable for this assess m e nt .
Howeve r, analysis o f com m e nts received from the disl ike question (question 7 )
provide reveal some clear prefere nces. The fact that 6 6 . 7 % o f respondents
described text u re as one of the attributes of category 4 that was d i s l i ked is a
sign ificant res u lt. The overall trend of increasing n u m bers of disl ike com ments with
increasing texture valu es also supports the notion that the tougher sam ples are
being l i ked less.
Making a claim regard i n g the threshold of acceptance can not be supported with
rigorous statistical sig n ificance with this type of data. However, it is entirely
reasonable to suggest from the com m ents, the threshold of rej ection for Saddletail
wou ld be very close to this valu e of 72 m i l l ijou les per g ram (mJ/g ) . Regardless of
threshold of rejection, it is apparent from this data that tou g hness at this level
46
Managem e nt of toug h fish syndrome
(approx 72mJ/g) is clearly disliked by two th i rds of th is panel of reg u lar seafood
con s u m e rs .
When this threshold i s applied t o data col lected from all Saddletai l snapper i n
previous field trips (n=504) , approximately 1 3% o f a l l f i s h m eas u red f o r texture,
exceed this value of 72mJ/g i n firm n ess. This can be applied to the entire catch
provided the sam ple set that we have is representative of the whole catch. F u rther
consu ltation with industry stake holders wil l deve lop a more accu rate estim atio n .
Once this has been establ ished, a value can be placed u pon t h i s portion o f the
catch , and appropriate m easu res can be considered to address the issue and
prevent toug h Saddletail from ending up in front of consum e rs.
47
5.5. Enzyme treatment o f Saddletail snapper to improve
cooked texture
As a di rect res u lt of stakeholder consu ltation, enzyme treatm ent was proposed by
the authors as presenting an opport u n ity to add value to fish identified as h i g h risk
to developing TFS. The goal of this work was to develop a 'proof of concept' for an
enzyme treated Saddletail fil let o r portio n . A review of com mercial ly avai lable food
enzymes approved for use in Austral ia was conducted.
Enzym atic treatm ent has been widely investigated as an opport u n ity to i m prove
the valu e of lesser quality cuts of beef (White h u rst and van Oort 20 1 0) . This is
ach ieved by degradation of the myofibrillar proteins ( i ntracellu lar) or the
con nective tissue (pri!'T!ar!!y co! !agen). A!m ost a!! proteolytic enzym es h av e activity
on both struct u re , however the degree of these activities can vary g reatly.
Enzym es from com mon food sou rces i nclude papain (papaya) , bromelain
(pineapple) , zing ibain (gi nger) , actinidin ( kiwifru it) and ficin (figs) are avai lable as
refined enzym es for use as food i n g redients. Many of these whole foods (e.g.
g i n g e r) have had centuries of use as i ng redients i n meat marinades designed to
ach i eve more acceptable meat text u re. More recently m any e n zymes from
m icrobial sources have been g ranted generally recognised as safe (G RAS) status
by both the U S F DA ( U SA) and FSANZ (Austral ia and NZ) for use as process i ng
aids i n food m an ufacturing.
I ncorporating one or m o re of these enzymes in a value-added fish product, either
as pu rified enzymes (e.g. seri ne protease) or as whole food i n g redients ( e . g .
g i n g e r) may provide m arket opportun ity f o r f i s h at risk o f presentin g with
tou g h ness when cooked .
Contact was made with an enzym e supplier in Australia. Advice was sought as to
the m ost su itabl e enzyme for or req u i re m e nts. The recommendation was to use a
plant derived protease at first and evaluate efficacy.
This view is su pported by other l iterature for the beef industry (Cal kins and
Su l l ivan 2007) . This e nzym e has demonstrates a preference for col lagen prior to
m yofibril lar com ponents of m uscle tissue And has also has demonstrated activity
at O 'C. Both of the attributes are essential for the application on Saddletai l
snapper in a val u e added product form at.
5 . 5 . 1 . Trial 1 : Dete r m i nation of effective dosage
Th is trial was s i m ply to determ ine the amount of e nzym e req u i red to i m part a
noticeable effect o n the cooked texture of the fish . Fish f i l l ets used in these trials
were left over B sam ples from field trip 8 (April 20 1 1 ) These B sam ples h ad been
stored at -29 'C si nce processing back i n May 20 1 1 . Theses sample also have
l nstron text u re m easu rements from the A samples analysed at this time.
.
Enzym e solutions were prepared with pre-ch i l led (4 'C) deion ised water at various
concentrations. Sadd letail portions were approx i m ately 40g each i n m ass , and
20m l of enzyme solution was applied per concentration and stored i n Glad zip- lock
bags, as can be seen in Fig u re 33.
48
- •.
, ;J ...
s · t"'.
'
�
•, .
.
...
F i g u re 33. Trial 1 samples after 24 h o u rs storag e at 4 °C.
Treated sam ples were cooked on an i nduction cook top using a non-stick frypan
and canola o i l . Sam ples were cooked approximately 3-4 m inutes per side or u ntil
deemed to be thoro u g h ly cooked. Samples were al lowed to rest prior to tasting for
approximately 5 m i nutes. A s u m m ary of the treatm ents and the com m ents from an
inform al taste panel are presented in Tabl e 1 4.
Ta bl e 1 4. s u mmary o f tna I 1 enzyme treatment.
.
Treat ment(g/L)
Vol u me(m l)
Sam ple size(g)
Comments
0 (control)
20
3 9 . 84
Very firm
0.2
20
42. 1 9
No d ifference
0.5
20
34. 2 1
No d ifference
1 .0
20
3 9 . 42
A ve ry s l ight d ifference
(softer)
2.0
20
4 1 . 86
More noticeable d iffe rence
Resu lts f rom this trial demonstrated that although the enzym e had a noticeable
effect, the dosage needed to be increased to understand the lim its of act ivity
better.
5 . 5 . 2 . Trial 2 : I ncreased dosage a n d efficacy ove r time
T h e second trial was t o u s e h igher concentration o f enzym e t o determ i n e efficacy
l i m its, and also determ ine the effect on textu re over a longer time period (7 days).
For this trial, in view of the longer time fram e i n cold storage, the enzyme solution
was adj usted with lactic acid to obtain a pH of 4.0. This pH wi ll reduce the
opportu nity for m icrobiolog ical g rowth , while not affecting the activity of the
enzym e d u ri ng the storage time. Ratio of fish portion to enzym e solution (2: 1 ) was
m ai ntained as per trial 1 . Sam ples were stored in barrier bags (250x 1 50mm) and
vacu u m flus hed at 95% vacu u m as can be seen in Fig u re 34.
49
..
-�
:;'J_
----.._..
F i g u re 3 4 . Samples prior to assessment d u ri n g Trial 2.
Fish portions were to be sam pled at 1 , 3, 5 and 7 days of cold storage. A
s u m m ary of the sam ples treatments and their identification is presented i n Table
1 5.
Table 1 5. Summary of Trial 2 treatments.
Fish I D
8026
801 5
8009
8059
E nzyme (g/L}
Day 1
Day 3
Day s
Day 7
0 ( ctrl)
D 1 CO
D3CO
D5CO
D?CO
2
D 1 C2
D3C2
D5C2
D7C2
5
D 1 C5
D3C5
D5C5
D7C5
10
D1 C1 0
D3C 1 0
D5C 1 0
D7C 1 0
Sam ples were cooked as previously described , and tasted by an i nformal taste
pan e l . A summ ary of day 1 resu lts are presented in Table 1 6.
.
Ta bl e 1 6. s u mmary o f d ay 1 resu I ts f or tr1a I 2.
Sam p l e ID
Comments from taste panel
D 1 CO
Firm textu re with noticeable con nective tissue
D 1 C2
Minor l evel of soften i n g com pared to the control
D 1 C5
Significant d ifference in text u re from contro l . Palatable sam ple.
D1 C1 0
Large d ifference i n textu re from contro l . A l ittle 'chalky' in m outh fee l .
Not very palatabl e .
50
Best resu lts were obtai ned from enzym e concentration of 5g per l itre solution. Th is
sam ple was sign ificantly softer than the control and q u ite palatable to eat.
However, the most striking res u lt was that of the 1 Og per l itre enzym e solution.
This sample had clearly experienced s i g n if icant enzym e act ivity. However, even
thoug h the texture was m uch softer, the organoleptic qual ities (or eating
experience) were qu ite poor and not des i rable. The sam ples did not really taste
m uch l ike fish. The experience was more l ike eating a beef or lam b meat that had
spent several hou rs i n a slow cooker. Clearly there is a th reshold of enzym e digest
that n eeds to be considered in future form u l ations.
Day 3 resu lts are prese nted i n Table 1 7. At this point, to ensure the ongoing safety
of the sam ples, pH values of the enzym e solutions were also take n .
Table 1 7 Su m mary of day 3 resu lts for trial 2.
Sample I D
Solution pH
Comments from taste panel
D3CO
6.25
Firm but not overly tough
D3C2
6.21
Very l ittle softe n i n g
D3C5
6.20
D3C 1 0
6. 1 6
Noticeable softe n i n g and loss of con nective tissue.
Sti l l q u ite palatable.
Too far gone. Al most m ushy.
Resu lts from day 3 were very m uch in line with those of day 1 . Enzyme activity
appeared to be having conti n u ed no further than the sam ples from day 1 . This
was confirmed after d iscussing these resu lts with the enzym e s u pplier (Enzyme
Solutions Pty Ltd ) .
T h e s u p p l i e r had previously advised the enzym e had the capabil ity to uti l ise itself
as su bstrate, and enzym e preparation shou ld o n ly take place i m m ediately prior to
addition to the su bstrate. So in this case, we can assu m e that all enzym e activity
h as ceased somewhere around the 24 hours post add ition to su bstrate.
The p H of the enzym e solutions had also increased to an u nsafe leve l . I nteraction
with the fish m uscle proteins, either with or without ass istance by the enzym e , had
buffered the solutions to a pH range that was no longer safe to store at
refrigerated tem peratures. For this reason, and the cessation of f u rther enzym e
fu ncti o n , this trial was d iscontinued at this poi nt.
5 . 5 . 3 . Trial 3 : S h o rt soak time treatm ents.
The trial i n volved using the enzym e as a short soak step of 30 m i n utes. Sim ilar
treatm e nts have been reported for soak times as short as 1 5 m i n utes (Quag l i a et
al. 1 992) . This style of treatment is also more applicable to a com m e rcial
processi n g operation .
For this assessment a relatively h i g h level of enzym e concentration ( 1 OOg/L) was
used at various time i ntervals. Sam ples we re kept refrigerated du ring the soak
time ( 4 "C ) in zip lock bags. The individual fish used for this assessment ( I D 8006)
was also previously determ i n ed as being very tou g h (90mJ/g) and represe ntative
of the very toughest of fish observed . Sam ples were cooked i m m ed i ately after the
51
com pletion o f the soak t i m e a n d assessed b y our informal taste pan e l . A s u m m ary
of th ese resu lts are presented in Table 1 8 .
Table 1 8 . Summary of resu lts from trial 3.
Sample ID
Soak time
Taste panel comments
S 1 TOO
0 (control)
Very firm . Noticeable con nective tiss u e
S 1 T1 5
1 5 m i n utes
Very l ittle difference if any from control
S 1 T30
30 m i n utes
Noticeably softer, but sti ll quite palatable
S 1 T60
60 m i n utes
Sign ificantly softer and unpalatabl e . Too soft ,
alm ost m u shy i n mouth feel
Soak time of 30 m i nutes provided the m ost palatable sam ple with sign ificant
reduction in tou g h ness. Howeve r, the enzym e concentration used in this trial was
far above what would be com m ercially cost effective . The extent to which further
activity contin u ed i n cold storage post-soak is also u n known . The value of this trial
is the cl ear demonstration of the efficacy of the e nzym e at 4 "C for com m ercially
efficient timeframes, even if the enzym e concentration is excessive .
5 . 5 . 4 . Trial 4 short soak t i m e a n d overn i g ht sto rage u nd e r vacu u m .
O u r previous trials had i ndentified the f i rst 24 hours of storage as being the l i kely
l i m it of activity for the enzym e on Saddletail portions. This allows the enzyme to be
treated as a processi ng aid with respect to the Food Standards Code (Standard
1 . 3 . 3 , Table to clause 1 6) provided the e nzym e has no further activity with in the
food . U nder these conditions, enzym e treatment wi l l be possible as a s h o rt soak
and t h e n transferred to vacu u m or modified atmosphere packag ing ( MAP) .
For this trial , th ree enzyme concentrations were used ( 1 0 , 30 and 50g/L) u nder a
soak time of 30 m i nutes . Sam ples were placed i n barrier bags for the duration of
the soak. Once the soak time had expired, the enzym e solution was drained from
the bag and a vacu u m seal (95% vacu u m ) was appl ied to the bag . Samples were
then transferred to the cold room (4 "C) for 24 h o u rs prior to inform al taste panel
assessm ent. The fish used for this trial was previously determ ined as being very
toug h (88mJ/g ) . A s u m m ary of resu lts and com me nts is presented in Tabl e 1 9 .
. 1 4
Ta bl e 1 9 Su m mary of resu ts an d comments f or T na
Sample
Enzyme(g/L)
Taste panel comments
S2COO
0 (control)
Very tou g h and chewy.
S2C 1 0
10
Slight reduction i n tou g hness. Qu ite palatable
S2C30
30
Sign ificantly softer. A litt le chalky but good flavou r
S2C50
50
Very soft and chalky. Not palatable
The action of the enzym e is clearly vis ible i n the fol lowi ng figu res. Figure 35
shows a cross section of the control sam ple.
52
Figure 3 5 . Cross section o f control sample from Trial 4 .
I ndividual m u scle blocks are b o u n d tightly together b y the connective tissue
between t h e m . In m ost fish species this collagen m e lts read i ly u pon cooki ng.
However as the authors have previously reported the col l agen with i n Saddletai l
snapper m u scle becomes less solu ble to heat as fish age ( Forrest et al. 20 1 0 ) . It
is these col lagen matrices that are the target of the enzym e .
F i g u re 36. Cross section o f 50g/L enzyme treated sample fro m trial 4.
Fig u re 36 demo nstrates the efficacy of enzym e treatm ent at 50g/L. Although this
sam ple was deemed beyond palatabi l ity by the taste pan e l , the action of the
enzyme upon the collagen m atrix is apparent.
Forrest and Poole ( 2 0 1 2 )
53
Management of tough fish syndrom e
5 . 5 . 5 . Conclu sions
These t rials have demonstrated t h e abi l ity o f a pu rified enzym e t o provide an
opport u n ity to treat fish previously identified with TFS and reduce the tou g h n ess to
a level that was deemed palatable by the i nformal taste pan e l . I nterestin g ly,
enzyme fu nction beyond a certai n point resu lted in a cooked Saddletail portion
that was not palatable regardless of the softness of the textu re.
The short soak followed by overni g ht vacuum packag ing also proved effective as
a model for fut u re product concepts . This m ethod com plies with cu rrent food
legislation with regard to enzym es as processing aids, and also offers a sim ple
m ethod that cou ld be i ncorporated wit h i n the time sensitive operat ions of a
com m e rcial process i ng facil ity. G reater shelf life wou ld be obtained by packag ing
after e n zym e soak in m odified atmosphere pack.
Enzym e concentrations were found to work best between 1 0 and 30 g rams per
l itre at a ratio of 2 : 1 ( F is h to concentrate vol u m e) . F u rther development is req u i red
to opti m ise the enzym e concentration levels to ach ieve the desired texture.
Optim isation is also req u i red to best fit individual processi ng operations for
processing time, labo u r costs and m aterial cost sensitivities.
54
6.
Benefits and adoption
Resu lts from t h is research project have delivered critical sound i nformation on the
cause of tou g h fish syndrom e affecting Sadd letail snapper caug ht in northern
waters. To date , lack of m arket confidence with respect to the eating qual ity of
Saddletai l snapper has been the key d river of u nder-valuation of this reef fish
species with i n Austral ia. The new i nformation that fish age is the m ain contributing
factor to the textural qual ities of cooked Saddletai l provides a bas is for sou nd
com m e rcial busi ness decisions.
In light of the di rect link between cooked flesh tou g h n ess and age of fish, the
resu lts from the research e n ables i ndustry stakeholders to reconsider how best to
market their product. Older fish that are more l ikely to exh ibit tou g h ness should be
excl uded from the h ig h -end table fish m arket where a prem ium is attai ned for peak
eati ng quality. Customers with in the m arket where quality is param o u nt should
only be su pplied with you n g e r fish and hence this will protect m arket confidence.
I m plementation of such a strategy wi l l be nefit stake holders and partici pants
throughout the su pply chai n , i ncluding consumers.
Work with i n the project also resu lted i n new and real i nform ation on consumer
perceptions of tou g h ness i n fish flesh. Consumer reaction to different deg rees of
toug h ness i n cooked Sadd letail flesh provides the basis for u nderstandi n g the
extent to which industry needs to i nvest i n solutions that wi l l m in i m ise the im pact
of toug h fish syndrome.
Strateg i es to m i n i m ise i m pact o f t o u g h f i s h syndrome
Fu ll real isation of benefits from this research can only occu r through selection of
practical TFS m i n i m isation strategies. Rem oval of older fish that are more likely to
be toug h u pon cooking will i m p rove the reputation of the species as a prem ium
table fish. The di rect resu lt of this wil l be an increase i n consumer confidence and
satisfaction of Sadd letai l snapper as a h i g h quality eating fish.
Developm ent of possible strateg ic options should a cause of tou g h ness be
identified, was a focus of this research project and to this end a specific
stakeholder m eeti n g was held to discuss the feasible options that could be
appl icable with i n com mercial reef fish business operations. An agenda of
suggested strateg ies was tabled at the m eeting as a bas is for d iscuss ion and
select ion of preferred pathway(s) . The discussion paper is attached to this report
i n Appendix 5 along with the m i n uted discussion outcomes .
From i n -depth discussion o f t h e options proposed , i ndustry stakeholders
determ i ned preference for two pathways forward : use of u ltrasound to sex fish
e ith er on-board or on-shore and enzym e soften i n g of fish f i l lets . Both th ese
options were considered theoretically feasible with i n the com m ercial fisheries
howeve r, the d irect appl icability and effectiveness i n reducing the i m pact of tough
fish i n the market n eeds to be determ i n ed prior to adoption by industry.
Pathways to adopti on and i m p lementat i o n
An assess m e nt of the effectiveness of u ltrasou nd data with respect to
differentiating fish sex in whole fish is necessary to justify industry i nvestment i n
expensive tech nology. I ndustry proj ect partners were keen f o r t h i s t o go ahead in
the near future.
55
M anagem ent of tou g h fish syndrom e
With i n t h i s cu rrent project, w e have provided add itional resu lts b y way o f a 'proof
of-concept' with respect to the appl icabil ity of enzym e tech nology for the softening
of tou g h fish fil lets . The plant derived protease, demonstrated positive benefit and
it provides a m arketing positive related to the source of the enzym e.
Of note , is the passion and com m itment by the key industry stakeholders to
prog ressing forward with a solution for TFS. This was strongly evidenced through
expressed wi l l i ng n ess to i nvest heavily i n additional i nfrastructu re and tech nology
should this be req u i red.
Com m u n i cati o n with Stakeholders and I nd ust ry
I ndustry stakeholders were kept abreast of project work d u ring the cou rse of the
project by way of regu lar updates through the NTSC qu arterly news lette r. Several
m eeting were also held in Darwin with key stakeholders during the cou rse at this
project. The m ost sign ificant of which ( N ovember 20 1 1 ) resu lted i n additional
outcomes being sought from the research i n line with stakeholder expectations.
One f i n al m eting wi l l take place in Darwi n in November of this year to present f i n al
report f i ndings and d iscuss future options.
Du ring the cou rse of the project , the prof i l e of the work completed so far has
resu lted in the researchers being approached by several i ndustry fig u res from
aro u nd the country i ncluding Pau l Richards ( D i rector Cardinal Seafoods Pty Ltd) ,
Ch ris Swal low ( P u rchas i ng and Marketing Adm i n istrator Kai lis B ros ) , Matth ew
Vuj ica (Supaf i n Seafoods Pty Ltd) and John Susman ( Fish eads Seafood
Strategy) .
56
7.
Fu rther development
7. 1. Consumer threshold of rejection for cooked Saddletail
snapper
Resu lts to date have provided a trend with regard to the t h reshold of rejection for
the texture of cooked Saddletail snapper. Howeve r, a g reater level of sign ificance
wou ld be obtai n ed from a redesigned questionnaire and a g reater n u m ber of
consu m e rs .
There a r e two areas o f consideration for redesigning the q u estionnai re . Fi rstly, the
size of the sam ple assessed by the consumer should be closer to the size of the
portion that wou ld be consu m ed i n the home or restau rant. For the pu rposes of
m ai ntai n i n g val id scientific method, portion size was u n iform across all sam ples
presented (2cm x 2cm ) . This is standard practice in cons u m er and sensory
assessm e nts.
However, i n this case, the cutting i nto a larger portion , or whole f i l l et of th is
species would have provided consu m e rs with more feedback with respect to the
texture of the fish portion. In this situatio n , consu mers wou ld be able to d raw upon
previous experience with cutting cooked fish portions. Th is is consistent with our
requ i reme nts for consumers to be qualified as regu lar cons u m e rs of seafood , and
we are d rawing d i rectly upon this experience for our resu lts.
Secondly, a m uch larger g roup of consumers is requ i red to permit more rigorous
analysis of the resu lts obtai ned. Ou r assessment relied u po n using Queensland
Governm ent staff available on site at Coopers Plains wit h i n the time avai lable, and
with l i m ited resou rces. A g roup of at least 1 00 consu m e rs wou ld allow for more
stringent qu estion i n g and analysis, and resu lt in more rigorous statements with
regard to s i g n ificant results.
7.2. Determine efficacy of ultrasound imaging
determining the sex of Saddletail snapper
for
Dete rm i n ation of sex wou ld certainly provide an opportu nity to rem ove the majority
of Sadd l etai l snapper at risk of exh ibiting TFS. Once the sex of any fish was
determ i ned , the m easu re of fork length could be used as an approximate for that
fish. Fork length data captu red during this project cou ld be added to existing
databases developed by N ewm an (2000 ; 1 996) and others .
T h e g roup that is the highest risk is m ature female. Matu re m al e f i s h g row m uch
larger than their female equ ivalents . Matu re females m ay also present a
reasonable straig htforward sex determ i nation by u lt rasou nd due to their large
gonads when m ature. Removal of fish at risk of exhibiting TFS wou ld provide
stakeholders with a strong m arketing opportun ity.
7.3. Optimisation of enzyme treatment
snapper within commercial protocols
of
Saddletail
Treatm ent of Sadd letail snapper portions with a plant derived protease shows
promise as a m ethod of obtain i n g more value f rom fish at risk of exh ibiting TFS.
57
Fu rther work wou ld add ress issues su rrou nding the i m plem entation o f the process
with a com mercial operation . These wou ld i nclude ;
1 . Optim isation of the dosage level req u i red to achieve significant resu lts o n a
com mercial scale;
2. Optim ise the ratio of enzym e solution to fish m aterial for com m ercial scale
3. Determ i n e opt i m u m MAP conditions for enzym e treated Saddl etail snapper
f i llets and portions;
4. Establish the shelf life of enzym e treated Saddletail snapper portions
(MAP, vacuum packed, and frozen ) u nder best manufactu ring practice
conditions ; and
5. Determ i n e m aterial cost efficiencies available for purchasing enzym e on
com m ercial scale.
Addressing these issues wou ld provide stakeholders with a sound basis to m ake
investment decisions as to the viability of developing enzym e treatm ent of
Saddletail s n apper portions into value added products for wholesale or retail.
58
8.
Plan ned outcomes
The m ajor plan ned outcome from t h is research proj ect was the determ i n ation and
confirmation of the cause of tou g h ness in Saddletai l snapper. Th is was ach ieved
convincingly with a d irect l i n k demonstrated between fish age and toug h n ess of
cooked fish flesh.
The influence of other physiolog ical factors were shown to have l ittle i m pact with
respect to fish flesh tou g h n ess. Additionally, there was no apparent con n ection
between flesh tou g h n ess and seasonal ity nor year to year conditions.
The poss i b i l ity of tou g h n ess being engendered throug h in appropriate ch i l l i ng
i m m ediately post-captu re was ru led out as a factor contributing to toug h fish
syndrome.
The plan ned outcome fol lowi n g on f rom ide ntification of the cause of TFS,
su rrou nded developing procedu res for reducing the i ncidence of toug h fish
syndro m e where the cause was preventable. However, as post-harvest handling
was not a contri butor to tou g h ness, i m plementing alternative hand l i n g procedu res
was not relevant.
Where the cause was identified as being less easily co ntrolled, the planned
outcom e refocused on m echanisms for identifyi ng tou g h fish, either on-board or
during processi n g steps. Th is has been ach i eved t h roug h provision of current
available tech nology i nformation on non-i nvas ive u ltrasonics and i m agery to the
industry partners . Additionally, the authors proposed several alternative
approaches to add ress m i n i m ising the i m pact of TFS. Each approach was
considered f u l ly with ind ustry at a special stake holder m eeti ng ( N ovem ber 20 1 1 )
and options reduced to the two m ost favou red by the key m em bers.
Due to the obvious passion and comm itm ent from industry towards resolvin g the
TFS issu e , and although beyond the scope of the project as stands, the authors
agreed to u ndertaking additional research to provide some i nform ation needed
next . The work included an assessment of consu mer perceptions of tou g h n ess in
Saddletai l flesh and 'proof-of-concept' trials with enzym e treatm ent of tou g h fil lets
59
9.
Concl usions
9. 1.
Cold shortening and 'cold shock'
Cold shorte n i n g was not observed i n Saddl etail snapper. The developm ent of rigor
mortis i n Saddletail occu rs at faster rates in ice slu rry than at ambient
tem peratu re. However, this is s i m ply the product of exhaustion of avai lable ATP
wit h i n the m uscle, and not a resu lt of cold shorten i n g .
9.2.
Drivers of TFS in Saddletail snapper
The prim ary d river of TFS in Sadd letai l snapper is fish age. The collection of fish
over fou r years of research has rem oved any previously held notions of seasonal
effect with i n the data set. There is also l ittl e or no d ifference between the textu re
values obtained for male and female Saddletail snapper. Any anom alies with i n the
resu lts are the product of a trip effect, and are not significant when exam i ned with
the larger data set.
9.3. A vailable technology
Stakeholders requested a summ ary of avai lable technology that m ay assist with
identifyi ng Sadd letail at risk of exh ibiting TFS. Two m ethods showi ng promise
were identified. These are u ltrasound i m ag i n g , and near i nfra-red spectroscopy.
Both tech nologies are available with i n Australia in various forms. The m ost
straig htforward application wou ld be the use of small an imal u ltra sound i m ag i n g
available to m ost veterinarians i n Austral ia. Detai ls o f suppliers o f th ese
tech nologies were su ppl ied to stakeholders.
9.4.
Consumer preferences
Our consumer t h reshold of rej ection m ethod did not provide statistically s i g n ificant
resu lts. Howeve r, analysis of the com m ents reveal an overall t rend that h as
i ndentified a valu e of approximately 72mJ/g of work done as point at which the
majority of consumers com m e nted that the fish portion they tasted was too tou g h
or firm .
Howeve r, even at this value at least half of t h e respondents wou ld not have l i ked
the sam ple of fish. So any attem pt to remove these fish would apply a threshold of
rej ection m uch lower. A reasonable value for this task wou ld be 60mJ/g of work
done.
Th is represents approximately 25% of the catch observed d u ring this research
and sig n ificant proportion of the com m ercial catc h . W ith this data in hand,
stakeholders now have the abil ity to apply resou rces com m ensu rate of the value
of catch at risk of TFS.
9.5.
Enzyme treatment
Enzym e treatm ent of Saddletail with TFS has proved to be worthy of f u rther
investigatio n . The enzyme displayed high efficacy and was relatively s i m pl e to
apply within a valu e added fish product concept.
60
Managem ent of tou g h fish syndro m e
Cu rrent food legislation req u i rements with regard t o the use o f plant derived
protease material are such that an enzym e treated product could be produced and
sold with i n Australia with l ittle regu latory h i ndrance. There would also be no
labelling req u i rements to l ist the enzym e as an ingredient, provided the enzyme
can be demonstrated to have no activity at point of sale. This has yet to be tested
c l i n ically. However, advice f rom the enzym e supplier provides confidence that
there wou ld be no detectable activity remai n i n g at poi nt of sale.
F u rther work wou ld req u i re the optim isation of the enzym e wit h i n a com mercial
fram ewo rk to develop efficiencies of process , cost and scale. Th is process wou ld
also invo lve the application of the enzym e to Saddletail portions wit h i n MAP and
frozen product systems.
61
1 0.
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66
Manag e m e nt of tou g h fish syndrome
11.
Appendix 1 : I ntel lectual Property
There are no i ntellectual property issu es arising from this research project.
Al l resu lts , findings and developed m ethods have been exte nded to the
stakeholders in the Northern Demersal and Northern Trawl Fishe ries. All
i nform ation belongs i n the public domai n .
1 2.
Appendix 2: Project Staff
Pri n c i p l e I nvesti gator:
Sue Poole Principal Seafood Scientist, I FT, DAFF (Qld)
Tech n i cal and Analyti cal staff :
Andrew Forrest Research Scientist ( Food Tech nology) , I FT, DAFF (Qld)
John Mayze, Principal Seafood Tech n ician , I FT, DAF F (Qld)
Pau l Exley, Senior Seafood Tech nician , I FT, DAFF (Qld)
Carl Pau lo, Senior Seafood Tec h n ician , I FT, DAFF (Qld)
Sharon P u n , Analytical Tech n ician, I FT, DAFF (Qld)
67
M anagement of tou g h fish syndro m e
1 3.
Appendix 3 : Co nsu mer panel q uestion nai re
The fol lowi ng is a print out of the actual question naire used for the assessm ent
from t h e prog ram used for the assessment (Com pusense 5 . 0 ) . The format is from
the software desig n fu nction and does not accu rately represent how the
qu estion naire appeared on the com puter screen .
Project : 201 2 TFS V 2 SESSION01
Welcome Text
W E LCOM E to the tropical s napper
taste session.
Please press 'conti n ue' and the
bottom of t h i s page to co mmence
the assessment.
I nstruction Text
Tod ay you wi l l be tast i n g fo u r s a m p l es
of steam ed fi s h and be as ked a s i m p l e
q u est i o n re l at i n g t o t h e eat i n g q u al ity
of each s a m p l e .
P l ease a n swe r t h e q u esti o n s as
t h o u g h yo u we re eat i n g t h i s f i s h at
home.
P l ease c l e a n s e yo u r p a l ate with wat e r
betwe e n s a m p l e s .
Tha n k You Text
You have now com p l eted the
assessment.
Than k you very m u c h for taki ng to
time to partici pate.
Please be s u re to col lect a treat on
the way out.
I nstructio n Typ e : P re-Quest i o n
Th i s sect i o n of the assess m e nt i s a s et
of q u est i o n s
68
re l at i n g to yo u r seafood b u y i n g and
co n s u m pti o n .
P l ease c l i c k o n t h e categ o ry t h at m o st
re prese nts yo u r a n swer.
Q u est i o n Text
W h i c h of t h e fo l l owi n g age brackets do you belo n g ?
C h o i ces : 5
Val u e
3 1 years o r l ess 1
Ag e 3 1 - 40 years 2
Ag e 4 1 - 50years 3
Ag e 5 1 - 60 ye ars 4
Ag e 6 1 years and above 5
Quest i o n N u m be r : 2
Qu esti on Type : M u lt i p l e Choice
Qu esti on Titl e : G roceri es
B l i n d i n g Cod e s : Stand ard
Qu estion Type : D e m og raphic
P l ace m e n t : Fi rst Opport u n i ty
Font N am e : Arial
Size : 1 O
I nstruct i o n Typ e : None
Quest i o n Text
H ow often do you buy t h e g roceri es in yo u r househ o l d ?
C h o i ces : 3
Val u e
A l m ost always 1
I s h are the p u rc h ase of g roce ries 2
a l m ost n eve r 3
Qu esti on Type : M u lt i p l e C h o ice
Qu esti o n Tit l e : p u rc h ase freq u e ncy
Question Type : D e m og raphic
P l ace m e n t : Fi rst Oppo rt u n i ty
Font N am e : Arial
Size : 1 0
I nstruct i o n Typ e : None
Quest i o n Text
H ow often do you buy fresh or f rozen seafood ?
C h o i ces : 5
Val u e
69
S everal ti m es a week 1
Abo u t once a week 2
Abo u t once a m o nth 3
abou t once eve ry 3 m o nths 4
O n l y at C h rist m as or E aster 5
Q u est i o n N u m be r : 4
Q u esti o n Type : C o m m e nt
Q u esti o n Titl e : species most p u rc h as ed
B l i n d i n g Cod es : Stand ard
Q u estion Type : D e m o g raphic
P l ace m e n t : Fi rst Opport u n i ty
Fo rce Answe r : No
Keyboard : No
I n struction Typ e : Post-Question
The n ext s e r i e s of q u est i o n s wi l l re l ate
to t h e sam p l es i n f ro nt of yo u .
I f t h e sam p l e yo u are req u e sted to
taste is n ot i n fro nt of you , p l ease
p ress the ' ass i stance' b u tton i n fro nt of
yo u on the rig h t .
P l ease be aware t h at t h ese a re w h o l e
f i s h sam p l e s a n d d e s p ite t h e g reat
care we h ave take n , y o u m ay
e n co u nter a bo n e o r scal e .
Quest i o n Text
W h i c h are yo u r 3 m ost co m m o n ly p u rc h ased seafood species?
(yo u can choose fro m any fis h , crustacean or m o l l usc)
Quest i o n Type : M u lt i p l e C h oice
Q u esti o n Tit l e : Acceptabi l ity q u esti o n
B l i nd i n g Cod es : Stand ard
Qu esti o n Type : Sam p l e R e l ated
Font N a m e : Arial
Size: 1 2
I nstructio n Typ e : N o n e
Quest i o n Text
P l ease find t h e fish sam p l e %0 1 and taste a port i o n of the sam p l e .
Is the textu re o f t h i s f i s h acceptable t o you ?
C h o i ces: 2
Val u e
Yes t h i s textu re is acceptabl e t o m e 1
N o , t h i s text u re is u n acceptab l e and I wo u l d rej ect t h i s d i s h 2
70
Manag e m e nt of toug h fish synd rom e
Q u est i o n N u m be r : 6
Qu esti on Type : Com m e nt
Qu esti o n Tit l e : Like co m m ent
Qu esti o n Type : Sam p l e Rel ated
Force Answe r : No
Keyboard : N o
I nstruct i o n Type : None
Quest i o n Text
W h at if anyth i n g d i d you l i ke abo ut sam p l e % 0 1 ?
Q u esti o n Type : C o m m ent
Qu esti o n Tit l e : d i s l i ke co m m e nt
Qu esti on Type : S am p l e R e l ated
Force Answe r : No
Keyboard : N o
I nstruct i o n Type : None
Quest i o n Text
What if anyth i n g d i d you d i s l i ke abo ut sam p l e %0 1 ?
Old Dept of P ri m ary Ind ustries and Fisheries M ay 1 8, 2 0 1 2 1 3 :52 P ag e : 1 0
Comp usense five 5 . 0 (2008/1 1 /27) (c) Com pusense I n c . 1 986-2008
71
1 4. Append ix 4. Comments from co nsumers
relat i ng to q uestion 6 and q uestion 7 of the
consumer assessment
Pl ease note : Spelling and typog raphic errors are left in t o provide exact
responses by consum ers.
14. 1. Like comments
Catego ry 1
Moist, m elt in the mouth texture, colour good
Tender, sweet
Really n ice and soft textu re
Good textu re, mouth feel and appearance. Liked most.
Moist tasty.
Very soft, easy to chew, very tasty, pleasant to eat.
Good flavour and soft flesh
Good textu re, soft, s m e l l fres h
Only just acceptable for firm n ess, taste OK
The texture is very n ice, firm , almost no smell. I l i ked the taste
Tender, but m eaty enough to bite into
Nothing really it was overall rather tasteless
Good flavou r and flesh m ore flaky
Flaked off really wel l , col o u r and texture good
N ice flavo u r,
Much n icer, more palatable and more moisture
Th is m eat is also solid and f u l l and the taste and smell is better the previous
sam ple
Sweet taste. F i rm texture
Tasted fresh
Textu re was soft and s l ightly falls apart but with a l ittle chewin ess to stop it being
mushy flaked we ll i n mouth .
Slig htly better colou r
Velvety, lovely favour and taste
Moist, had flavo u r, sm ooth textu re
Firm but tender texture, m o ist, good colour
Reasonable texture and moisture
N ice l i g ht textu re, more subtle flavour than previous two sam ples
N ice wh ite fles h , great texture
The fact that it is a bit ch icken l ike
Moist, subtle flavou r
N ice a n d mo ist f i s h with not a strong s e a s m e l l
Fairly strong flavou r even text u re
Flavou r and s m e l l
Soft texture, colour, flavo u r
Reasonable flavou r
Texture and flavour were f i n e f o r m e .
Flavo u r
Flesh was a l ittle flakier than the previous a n d d r i e r or l est moist
Good flavou r, not dry and it flaked apart n icely Was not too tough
72
Managem ent of toug h fish synd ro m e
Easy to eat, melts i n you r mouth
N ice
The text u re was good, a little ch ewer than the previous sam ple, n ice fish taste, a
stronger taste though than the previous sam ples but was qu ite pleasant.
The s l i g ht saltiness
Taste and flaky texture
Tastes better than 785 , l ike the flakiness as opposed to the hard n ess of 758
Best text u re because it was flakey and easy to cut with fork, m i ld flavo u r and smell
Good eatin g , good m outh feel
Flaked easi ly, fres h taste
Textu re exce llent, flavou r enjoyable
Taste , lack of bones
Good textu re
S l i g ht oily/fish flavour
J:: a sy to cut
Categ o ry 2
m oist, good colour, good after taste
moist, white,
the sam ple has clean-f resh taste
Appearance is good
Soft, moist, easy to chew
Soft flesh
good texture, soft m eat, smell fresh
firm , moist
I liked it, sim ilar to the previous, with firm m u scles,
low s m e l l and n ice taste.
m eaty texture a bit l ike ch icken
firm texture, no strong fishy smell
its firm n ess wou ld be su itable for it to retain d u ring cooki ng in eg a cu rry etc.
Retained flavou r
firm textu re wh ite colour
n ice s m e l l , firm texture, good flavou r
t h i s fish is o f a m i lder textu re a n d flavou r t h a n 524,
The m e at is solid and f u l l . This can fill u p with only a small amou nt
not a strong taste
best mouth feel, sm ooth and moist, segments fel l apart wh i le chewing
firmer than 524 and 1 22 but sti l l h i g h l y acceptable
flake sections broke apart easily i n mouth but m ore
resi l i e nce d u ri n g chewing
fishy, moist, same taste as sample 525
sm ooth texture , n ice flavo u r
j u icy
moist but f i rm texture.
M i ld to pleasant fish taste
I didn't particu l arly l i ke it (wo u ld ran k it 3rd of the 4 samples) .
firm texture but not too firm
its tenderness
very moist
very soft textu re and moist i nside
G R EAT taste for m e , excellent flavo u r and texture!
flavou r and smell
n ice and m oist
flavou r
good textu re - bette r t h a n 1 24.
73
Management of toug h fish synd rome
good flavou r.
A l ittle more tender than the previous 2, Flavour
sim ilar. All good
Fleshy, mo ist
M eaty but not too tou g h , and not too dry
n ice
less dense not as good as 526
text u re was nice and fish taste was n ice and m i ld
less so than the previous sample.
I l i ked the softness of this sam ple and it had a
slight sweetness to it
taste and textu re
tastes ok reasonable textu re
very n ice flavou r, visually appealing (n ice wh ite flesh) , good fishy taste without
being too strong
firm , reasonably flavou rso m e
sweete r, nicer texture
Good f l avou r , firm texture.
firm texture
no bones
Good textu re and flavou r
It's q u ite j u i cy. the f i s h muscles separate wel l , s o it's easy t o cut with a fork.
Categ o ry 3
good after taste
tender
i really l i ke the smooth texture
Good appearance and mouth feel
You left some scales i n it, u ncool .
moist
text u re ok, taste good.
sm e l l fresh, the texture is ok
firm , m o ist
Sim ilar to the previous, but the texture seems harder, taste ok. I personally like
fish with firm flesh
tender texture, but sti l l 'm eaty' enough to bite into, sweet-briney flavo u r
i t had a stronger ocean taste and s m e l l and overall
it was qu ite pleasant to eat
good flavou r and sti ll qu ite f i rm .
g reat textu re, flavour less l ike bait more l i ke a n ice quality fish
even colour, n ice smell
Tu na - l i ke textu re, firm and strong taste
I don't m i nd eating this sam ple but the smell is a bit strong when I open the
sam ple but it tastes O K afterward
Firm . Not too strong a taste .
som e what m oist texture was excellent - flaked we ll with just rig ht amount of
res i lience expected i n large flaked fish flesh
Firm and easy to cut using fork.
fishy taste , cooked ok, moist
smooth texture , n ice taste, m oist
colou r is good, text u re is f i n e
moist but f i rm text u re
Slight flakiness of texture
74
Manag e m e nt of tou g h fish synd ro m e
its salt i n ess
moderate textu re
n ice and soft
strong flavour
flavou r and s m e l l
n ice a n d mo ist
wh ite colour, moderate ly soft textu re, flavo u r
better textu re t h a n 1 24.
good taste
Probably this sample ( l ike the last one) was a little m ore tender than the fi rst 2.
Flavo u r of al l 4 was consistent.
Sweet f lavour, j u ici ness
Fleshy and tasty not dry or flakey
Fish was meaty and j u icy, not too d ry and qu ite flavo u rsom e , although not strong
fishy taste
Nice s mooth taste , not too fis hy, n ice and flakey
Better than 1 24. Less dense and flavou r good .
A really n ice fish taste but no ove rpoweri n g , textu re
was softer than 757.
textu re and taste
firm texture, nice ocean fish taste, not too st ro n g ,
l o w odo u r
o k , reasonably f i rm , bit chewy
o i ly, chewy
Not m u c h - taste ok
no bones
textu re
flavo u r O K
Qu ite hard t o c u t i t . It s e e m s really com pact b u t i n m outh it's not really disg usti ng.
It sticks a bit to my teeth, not really enjoyable.
Categ o ry 4
wh ite colour
Good mouth fee l , slight fishy odo u r
taste was ok
Tasted fresh
smell fresh ,
taste is O K
I sti l l l i ke i t , b u t I preferred the previous ones.
S i m i lar characteristics with the previous
flavo u r n ice
it had a l ittle m ore flavou r than the previous 343
the flavo u r was a l ittle more ocean ic than 343
firm , very l i g htly flavou red
firm , smelt n ice, not too flakey
it is edible but not my choice of fish
the taste is sim i lar to sam ple 1 22 .I find no problem with this sample also Good
Taste
good flavour, mo ist and good mouth feel
j u st border l i n e ok - su itable for cu rries perhaps
A bit more flavo u r
d ry b u t tasty
75
Management of toug h fish syndrome
sm ooth texture , n ice flavour
fish flavour, tender texture , n ice colou r
Not m u ch.
n ice white colour, firm textu re but not too firm
soft fles h , not chewy
ve ry m o ist, qu ite firm good for cooki ng cu rry
Has a nice fresh taste
n ice appearance (f lakier) good flavour and n ice textu re
flavou r and smell
n ice and moist
col o u r, moderately soft texture,
reasonable flavou r.
All good ag ai n
Fleshy and fresh
Good f l avo u r and not dry
not a m uddy taste, not salty
less dense but funny taste
It has a n ice m ild fish taste and is not
overpoweri ng, was q u ite e nj oyable taste
wh ite , well presented
n ice f i rm texture, low odo u r
ok
tasted 'clean a n d fresh'
texture firm , flavou r good
no bones taste
flavour Ok
14.2. Dislike Comments
Catego ry 1
bland
No specific dislike
n/a
no
a bit too firm
noth ing
a bit powdery text u re at the finish
i found that it had a rather strong scent and the flesh was not as f irm as the
previous 755 and 343
a littl e m oister but sti l l a tad d ry
wei rd taste not fishy but more d i rty . . . .
not as tightly packed as others , somewhat u n even
i n colo u r , slight s l i m i n ess betwee n the flakes of f ish
Nothing
Noth i n g . I like the smell taste and texture of the fish
Nothing
A bit dry in the m outh when chewi ng
nil
nil
76
sam ple tasted fine
plain flavo u r
bland taste
I qu ite l iked it, but wou ld like to taste it with flavo u r enhancers (lem o n , sauce or
spices) .
a bit floury taste
did not taste as fresh
m etal lic aftertaste
Maybe a l ittle drier than I wou ld prefer, but sti l l fine.
Althou g h text u re was acceptable, it was s l i g htly chewy
not as flavoursom e as previous sample
Noth ing it was very n ice
nil
Maybe a l ittle dense
No
A l ittle chewy
noth i ng
noth i n g
noth ing
noth ing
Noth ing
noth ing
Nil
A l ittle bit d ry. It sticks a l ittle bit to m y teeth, but less than sam p l e 527.
Catego ry 2
slightly bland
Little bit fibery
bit dry
not very tasty
Less flavo u r com pared to 754
no
a l ittl e too firm
noth ing
It was a little bland
perhaps a l ittl e dry
a l ittle too fish flavoured , I prefer a m i lder flavo u r
A slight 'sli m iness' at first
Again t h is is tu na or shark -like flesh very wholeso m e but tasteless
The taste is bit strong and fishy
Not much taste at all
noth ing
nil
Seem to a bit leathery
nil
noth ing
inconsistent colo u r (some black dusts wit h i n tissue
& brown s u rface), stringy textu re
nil
Textu re a bit too firm . Flavour qu ite strong - almost muddy.
a bit dry but it is the best for m e so far
77
Management of tough fish synd rom e
does not taste fresh and didn't have t h e s e a s m e l l at al l which m ade i t tasteless
brown colour, firm texture
No problem
Slightly bland flavour
Diffe rent Fish taste didn't taste l ike ocean fish but was n ice
Noth ing
a l ittl e chewy
the flavour not as good as 526 m aybe 345 a l ittle
soggy
no
presentation , it looked a bit too brown
noth ing
noth ing
maybe bit too firm , didn't melt i n the m outh
Nothing
nothing to report
Nil
Catego ry 3
slig htly dry
tender to eat but hard to p u l l apart
fishy backnote
woops, see previous.
A l ittle d ry.
Fish tasted old, chewy and lack of flavo u r
the m eat is not soft enough
noth ing
noth ing
noth ing really
this was fine but sti l l a touch dry
slight dark colo u r on botto m .
more slimey i n textu re on t h e tongue
this type of fish n eeds more flavour
by itself not very tasty
I don't l i ke the smell of the fish at first but it sti l l
passes my test
Nothing
a bit dry and crum bly
nil
nil
noth ing tasted fine
plain flavour, springy textu re, not j u icy
bland taste
Flavour wasn't overwhelm ingly good
'Fishy' taste too strong, too tou g h
a b i t chewy a n d a bit too hard
slight m etal lic flavou r
a bit rubbery
strong bitter aftertaste
No problem
78
Managem ent of toug h fish synd ro m e
N/A
I prefer fish that flakes away a l ittl e more but it wasn't u npleasant
Nil
that was pretty good
No it was g reat
A little chewy and a bit bland
noth i ng
bit rubbery
didn't look as n ice as usual fish with brown l i nes through it. not as visually
appealing
bit too firm & chewy
oops wrong com ments in last box
oily and chewy and smell
Textu re rubbery, flavo u r ok but bland
noth ing to report
Ru bbery texture
Too hard to cut with a fork. sticky to the teeth . And I prefer when fish kind of me lts
i n m y m outh .
Catego ry 4
slightly ru bbery in the mouth
sl d ry
the texture of the sam ple is a bit chewy and rubbery
Odou r
It see m ed to be a l ittle bit, but not u n acceptably (to m e ) , toug h and perhaps a little
d ry too .
a bit dry
textu re was rubbery, overcooked , hard to chew
A littl e Chewy
the texture is not very good , the meat is not soft
f i rm to the poi nt of hard
The col o u r of the meat was not as white as the other sam ples. Taste is sti l l ok, but
I preferred the one imm ed iate ly before .
too chewy, as though it was dried out but it was stil l
j u icy?
it was perfectly fine
sti l l a bit dry
Strange textu re. Very firm and didn't seem to have the layers
wou ld be disappoi nted if this fish texture was presented in restau rant
too d ry
a bit dry and denser in textu re
1 dry m outh feel
Ru bbery texture
bland taste
Ru bbery texture.
the strong remai ning taste
not as soft
texture a l ittle f i rm , but sti l l acceptable
Maybe a l ittle drier than I wou ld have l iked, but sti l l OK
Textu re was like rolled ch icken loaf and dry
79
n/a
A l itt le bit 'chewy' or 'rubbery' - did not m ake it u npleasant but it defin itely didn't
flake away nicely
the way I l i ke m y fish.
Not very flakey
taste not as good as 1 24
It was a bit chewy as if it was over cooked
Too chewy
texture a little bit ru bbery
nothing
a bit chewy
bit too f i rm
l ittle bit toug h
Noth ing
nothing to report
too dry
Really compact. It looks more like a ch icken texture. It sticks a bit to my teet h . I
wou ldn't like it i n a 'cooked fish dish' but why not if it was covered with a butter.
80
Manag e m e nt of tou g h fish synd ro m e
1 5. Appendix
5:
Discussion
material
and
stakeholder meet i ng m i n utes (Novem ber 201 1 ) .
Discussion poi nts for dec i s i o n on next act i o n s
FRDC Project 201 0-207 : Tou g h ness i n Sadd leta i l snapper flesh
P roj ect obj ective 4 :
To develop recommendations and strategies for industry stakeholders to
minimise the impact of tough fish syndrome
Where we are at . . . .
•
•
cau se o f toughness ide ntified - co rre lated t o age o f fish
fish > 1 5 yrs old have h i g h e r likeli hood of being tough
so where to next ? - several approache s : ( i n no specific ord e r)
Tou g h ness - co nsumer percept ion
•
•
need to estab l i s h the leve l of to ughn ess that is u nacce ptable to co nsumers
this w i l l establish what porti on of the catch affected co nsumer perception-wise
Methods to determine age
To d ifferentiate tou g h fish from rest of catch - ideally n eed to age fish o n back deck
• length (or weight) correl atio n s
• s e x determination
• otol iths (ear bones) - visual I near infrared ( N IR)
• scal es - N IR
Processing technology
•
•
•
enzyme treatment - whole fish I fil let stage
o
papai n (papaya) , bromelain (pi neapple) , zing ibain (g inger) etc
high pressure processi ng - valu e-added products
produ ct concepts
Market placement reposit ioning
•
•
consumer information
major q u al ities of Saddl etail
81
Management of tou g h fish syndrome
TFS stakeholder meet i n g
Present:
-
02 Novem ber 201 1 (NTSC, Darwi n)
Bill Passey, Horst Fischer,
Katherine Sarneckis ( NTSC ) , Rob Fish ( NTSC)
Andrew Forrest ( DAFF QLD), Sue Poole ( DAFF QLD)
J u l ie Martin ( NT Fisheries)
Mai n discussion outcomes :
1 . Andrew provided the resu lts and knowledge ach ieved to date with in the proj ect
(sum m ary attached - PowerPoint) .
flesh toug h ness is correlated to fish age - the older the fish, the m ore l ikely
it wil l exhibit toughness
Saddletai l are difficu lt to age onboard as usual fish length correl ation
methods are not appl icable for this species
•
•
2. Male fish are typical ly larger than female fish - however need to exam i n e
i nternally to determ i n e sex
fish cou ld be sexed at processing
d iscuss ion ranged i nto in-line tech nologies possible to sex fish i n whole
state
x-ray, u ltrasound, imag i n g were m e ntioned
•
•
•
Action
desktop study u ndertaken to s u m m arise possible tech nologies and
AF/SP
any cu rrent application worldwide
-
3 . N eed actual i nformation on consumer perception o f tough ness - wh at l evel of
tou g h ness is u n acceptable and hence what portion of the catch is i nvolved
Action
carry out cons u m e r acceptance/rej ection assessm e nt . Desi g n ,
conduct a n d interpret
AF/SP
-
4. I nterest i n enzym e use during processing to reduce flesh tou g h n ess
enzymes from natu ral sou rces available com m e rcially - papain (papaya) ,
bromelain (pineapple) , zingibain (ginger)
successf u l ly used i n the m eat industry
treatm ent cost /kg i m portant factor
•
•
•
Action
design and conduct proof of concept trials to determ i n e the success
of enzym e treatm ent in reducing flesh toug h n ess
AF/SP
-
82

(Lutjanus malabaricus) to re-instill eafood Council

Transcription

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