1 Organic sugar production at Guysuco at Uitvlugt Factory – First trial

Organic sugar production at Guysuco at Uitvlugt Factory –
First trial in the Caribbean: the factory experience
D. Ompertab
Guyana Sugar Corporation
Abstract
Organic sugar, the first in the Caribbean was produced at Guysuco’s, Uitvlugt estate.
Production commenced during the beginning of the 2nd crop 2002. Growing canes and
sugar production required approval license from the Soil Association for Organic
Farming and Production (UK). Their requirements have to be strictly adhered to by the
field and factory; the factory requirements are discussed. Manual weed control and
application of manure as fertiliser was found to be expensive. Processing juice and
clarification posed a major problem as no flocculant was authorised. Consequently, a
low throughput was achieved and increased production cost resulted from the demand
for fuel. ‘In Conversion’ organic sugar was produced in 2002, and 350 tonnes Organic
sugar in 2003. To date, the overview for expansion is considered for premium price.
KEYWORDS: flocculant, license, organic farming, organic sugar, processing.
Introduction
Guysuco comprises of eight estates operating as five administrative bodies, covering a
total cultivation of 46,500 Ha. Uitvlugt estate cultivates 6086 Ha for production of sugar.
This estate was selected as the pilot estate for organic cultivation and organic sugar
production and this project commenced September 11, 2000. Organic canes were
cultivated on an additional 500 Ha of land that was abandoned in 1986.
Mid year of 2003, a representative of the British Firm, Soil Association Organic
Standard confirmed all inspection reports and tests, and certified the operation as
organic. Prior to this, an annual inspection in 2002 was done at Uitvlugt Estate, which
included the sugar cane grown on the 500 Ha of land used to produce ‘in conversion’
Organic Sugar in 2002. The license was obtained July 30, 2003 and granted when both
factory and field operations complied with the standard.
For ‘organic’ production, the use of agrochemicals and processing aids (with the
exception of lime) is not permitted. In 2002 ‘in conversion’ organic sugar was produced
under the Certifying Body rules. For ‘organic sugar production, use of flocculant was
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barred and hence the quality of the clarification process whereby the ‘mud’ separates
from the juice was of major concern. Clarification affects the quality of the final sugar
and performance of vessels in the processing house. Careful operation of the clarifier
with continuous monitoring was required.
Organic cane was processed during the second crop of 2003 after completion of the
mid year maintenance and in August 2003, Guysuco - Uitvlugt Estate became the first
sugar factory in the Caribbean to produce 350 tonnes Organic Sugar in 2003. During
the first trial in 2002 ‘in conversion’ organic sugar was produced.
Exhibit samples of Organic Sugar
The specifications for organic sugar for direct consumption from a prospective customer
are shown in Table 1. These specifications are very strict with regards to colour, ash,
bacteria, yeasts and moulds. With the current processing techniques within Guysuco,
we would not be able to achieve these specifications for direct consumption. Hence, for
marketing of sugar, we would have to target organic food, beverage confectionery
producers where the sugar is re-processed.
Table 1: Organic sugar specifications from a prospective customer
Specification
Colour
Ash
Invert
Pol
Dextran mg/kg s.s.
Moisture
Size
SO2 (mg/L sulphite)
Mesophilic bacteria
cfu/10g
Yeast (cfu/10g)
Mould cfu/10g
Dark Demerara Light Demerara
4582
1641
0.344
0.196
0.79
0.3
97.73
98.9
37
10
0.437
0.165
MA1.0mm,CV15
MA 0.58-0.70 mm cv 35% max
0.96 mm/ 19%
%
10
<10
<10
Light Demerara
500-700
0.15
N/A
99.3
N/A
0.1
<30
1400
120
<5
<5
<40
<40
<40
<40
.
2
Parallel production is visualised for the future with continued production of organic and
non-organic canes, where organic and non-organic canes would not be harvested
simultaneously. With the growing demand for organic sugar to satisfy organic food,
beverage and confectionery production, there is room for expansion of organic sugar
production. This sugar will be able to attract premium prices compared to current raw
sugar. To date, four prospective buyers have offered US $500 - $600 per ton of sugar.
Background - field
Production of organic sugar requires organically grown canes. Cultivation commenced
in 2000 on approximately 500 Ha. of land in an area which was abandoned since 1986,
and free from chemical applications. Additional land in this area is available for future
expansion. The soil is acidic and similar to the lands used for non-organic cultivation.
The variety DB75159 was selected based on growth experiments and its suitability to
acidic soil conditions at Uitvlugt.
The organic cultivation area is flat and the fields are separated by canals, to facilitate
drainage and irrigation; and transportation of cane via punts to the factory. Initial
propagation of cultivation was done using conventional grown canes to produce organic
seeds for further propagation. Recommendation was made to reap canes without
burning, however, due to an industrial relation situation; the traditional method whereby
canes are burnt to de-trash was used. The alternative method would be costly to the
field but a higher yield would have been realised.
Section of Organic Cane
Land preparation
Aspects of cultivation practices must adhere to the standards as set out by the certification
body, some of these practices are outlined below:
Fertiliser and Plant Nutrient Supply: low grade phosphate lime (LGPL) was used to
increase the soil pH, and there were no other supplementary nutrients. Cows’ manure was
used on the cultivation, and legumes planted between rows.
Weed Control: no herbicides are permitted; weed control was strictly manual – mechanical
hoeing done in early stages (0-8 weeks) and later hand weeding. Other practices such as
trash mulching also aid in suppression of weeds.
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Pest & Disease Management: no chemical control permitted, physical methods e.g. using
traps, flooding cultivation used to eliminate pests. Variety of cane selected based on
resistance to viral and fungal diseases.
Water management: Irrigation is with ‘fresh’ water supplied from the Boeraserie
Conservancy. A no-fly zone for the agriculture aircraft was demarcated around the organic
fields and conservancy. The selected organic area obtains its water direct from the
conservancy without passing through the conventional cultivation. Drainage boxes are
designed to prevent contaminated water from flowing back into fields.
Manual applications required, for weed control and application of manure pose an
additional operating cost for the field. The following table shows the cost of the field
activities for 2000 to 2003. The year 2000 represents starting of this project. (Figure 9)
Activity
Land Preparation
Weed Control
Composting
Harvest
Planting
Drainage
LGPL
Others
Total
Table 2: Cost – Organic cane cultivation, G $’000
2000
2001
2002
8,991.00
1,215.00
298.00
6,081.00
7,492.00
7,184.00
-901.00
1,782.00
10,918.00
6,549.00
5,452.00
3,809.00
102.00
240.00
1,924.00
1,874.00
1,769.00
18,418.00
-4,751.00
---50,141.00
18,133.00
21,476.00
2003
-5,632.00
2,697.00
5,898.00
-2,240.00
-753.00
17,220.00
Factory requirements for organic sugar production
To fulfill the requirements for organic production, compliance to special procedures and
documentation were required by the certification body and these include the following:
Hygiene and general and cleaning requirements: There was special focus on cleaning
of the entire factory. During mid year maintenance, the factory was washed thoroughly to
remove traces of non-organic canes. Out of crop, weekly and daily cleaning activities
documented in the cleaning schedules. Cleaning was done using the pressure washer, hot
water and steam; maximum use was made of skato skalo equipment to de-scale the
internals of juice heaters, evaporators, pans, syrup lines and molasses lines.
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Skato skalo motor
Pressure washer
Pest control requirements: area in sugar bin area and sugar store sealed with mesh to
prevent entry of bats, birds and insects. Rat traps were also set in the factory.
Laboratory reports and analyses sheets: to be clearly marked organic.
Cane tickets and punts: The punts to be cleaned of all non-organic cane prior to loading
of organic canes. The Cane ticket of a different colour and clearly marked organic cane
with details of field number and time cut and delivered.
Milling: No biocide should be used during the period of grinding organic canes. Only hot
water and steaming allowed for mill cleaning and DSM screen cleaning.
Juice clarification: Milk of lime (0.750 kg. Per tonne cane) is the only additive approved.
Use of flocculant not permitted and the flocculant tank was isolated. The filter cake
considered as organic filter cake to be returned to the organic fields to be composted and
used as organic fertiliser. {Note: Production of ‘in conversion’ organic sugar in 2002,
flocculant, Magmafloc LT 27,4 ppm on cane, was used.}
Pan boiling: The normal three boiling system will be used. A and B sugars will be bagged
and the C Sugar re-melted and made into magma which will be used to seed the A and B
massecuite. The first strikes will be made from slurry prepared from Organic sugar from
previous crop. Use of hydros not permitted.
Sugar: The sugar will pass through a magnet to remove metallic extraneous matter. The
sugar sieve on order from Gough Engineering UK was not obtained before factory startup.
The sugar bins were covered; and the sugar bin area and sugar store insect and bird
proofed.
Sugar packaging and labeling: The sugar bags - 25 kg polyethylene lined woven
polypropylene sacks, specially marked and labeled approved by the Soil Association.
{GUYSUCO Logo)
+
100 % Original Demerara Organic Cane Sugar
PRODUCE OF GUYANA
+
{THE SOIL ASSOCIATION Logo}
5
Molasses packaging and labeling for molasses: The molasses will be from the
continuous centrifugal when the C massecuite is cured. The molasses is weighed and
pumped to the specially designated stainless steel tanks at DDL for storage. For shipment,
200 litres molecular weight high-density drums will be used.
{GUYSUCO Logo}
+
Demerara Organic Molasses
205 litres (45 glns)
Produce of Guyana
+
{THE SOIL ASSOCIATION Logo}
Organic sugar specification
Particle Size
Mean Aperture
Coefficient of variation
0.7 - 0.8 mm.
30 – 35%
Typical analysis
Polarisation
Moisture %
Safety factor
Ash %
Colour (420 mm)
98.0 – 98.5
0.3
0.20
0.4
2000-3000 icu
Organic molasses specifications
Brix
Total Sugars
Sucrose
Invert Sugars
Sulphated Ash
pH
80 – 85
50 – 60
30 – 35
18 – 25
12 – 15
5- 7
Processing techniques for organic sugar
The factory successfully fulfilled the requirements and organic sugar production started on
Saturday, August 8th, 2003. Based on the amount of cane expected, a production of 320
tonnes was expected.
Prior to Grinding
The factory was thoroughly cleaned. The factory assisted the field to wash all punts using
the punt dumper and hydrant nozzle pressure prior to loading of organic canes.
6
Grinding
The cane passed through two sets of steam turbine driven knives: the Leveller knives (first
set) and Reverse rotation design knives (second set) which cut the cane stalks into fine
pieces with a preparation index, PI of 86%. The average throughput was 95.8 tonnes cane
per hour.
Steam turbine
Milling cane- first stage
Feeding bagasse to mill # 4
Shredded cane was fed to the 14 roller tandem (consisting of a crusher and 4 three roller
mills). Hydraulic rams on the top rolls and application of imbibition aid extraction. Screened
juice was sent to process.
Juice treatment and clarification
The certifying body only permitted the use of lime as a processing aid. The management
team along with the factory personnel continuously monitored the performance of the
clarifier during the operation. Juice heating and pH control were closely monitored to
achieve the best possible clarification and hence sugar quality. To minimise turbulence in
the clarifier, the flow of juice to the clarifier was reduced significantly by reducing the juice
flow to the clarifier.
Bach Clarifier
Sampling points (2 of 8) on clarifier
Liming application (Cold Liming)
Limed juice was pumped though a series of four juice heaters, and to the clarifier via the
flash tank. The clarifier is a continuous clarifier – Bach design, with seven sloping trays.
7
Filtration
High mud volume of a thin consistency
expected and to remedy this the filter was
operated one and half times its normal
speed to cope with the increase mud
volume. The filter cake was transported to
the field to be used to prepare compost
for the organic fields.
Filter – filter cake removal
Evaporation
Clarified juice passes through the
quadruple effect evaporator where about
84% of water is evaporated from juice
leaving syrup of 60 to 65 degrees brix.
Evaporator station
Sugar boiling and Crystallisation.
For organic production, the conventional three massecuite system (A,B,C) of boiling syrup
and molasses was employed. Slurry was prepared using organic sugar. Crystals in the
massecuite were inspected for grain size and uniformity of growth to ensure good quality
of the final product. Massecuite are cured in crystallisers equipped with stirring arms.
Vacuum pan controls
Observing crystals in massecuite
Centrifugation
Centrifugation separate the sugar crystals from molasses. Sugar from A and B massecuite
form commercial sugar. Sugar from C massecuite was re-melted and used as magma.
8
High grade basket
Low grade
basket
Packing and Storage.
Sugar is transported from the centrifugals to bins where they are temporarily
stored before shipping as bulk, or
bagging.
Sugar Band Conveyor
Organic Sugar Crystals
Secure bond for Organic Sugar
9
Conveying bags to storage area
Results
A total of 6534.62 tonnes cane was ground, the daily averages for 9/8/03 to 16/8/03 are
shown in figure 1. Total grinding time was 68.25 hours with an average throughput of 95.8
tonnes cane per hour, see figure 2 for grinding rate for the grinding periods. Figure 3
shows the purity profile of the mixed juice for the grinding period. 350 tonnes of organic
sugar was produced and 134 tonnes organic molasses.
pH control and heating were of utmost importance since flocculant was not used, the pH
profile of mixed juice, limed juice and clarified juice is shown in figure 4 and depicts good
pH control. Fair clarification resulted due to the reduced juice flow and increased residence
time in the clarifier, which was attributed to intermittent grinding due to factory stops along
with the added advantage of the clarifier design.
Analysis of clarification results:
The quality of clarification is indicated by turbidity (average 35.32), sugar colour (average
3139), insoluble solids (average 696 ppm). The trends in these values are shown in figures
5, 6 and 7 respectively.
There was efficient heating and pH control and decreased juice flow to the clarifier
(minimum disturbance). However, good clarification was not achieved as indicated by the
turbidity values. The sugar colour and insoluble solid content indicate that there was
carryover of mud into the clear juice. Grinding was discontinuous as depicted by the actual
grinding time and the out of cane periods experienced, see figure 8. (Downtime was 11.83
hours due to low steam on the first day grinding and the remaining downtime due to out of
cane - weather). The discontinuous grinding though it required more fuel for constant startup and shutdown it was an advantage as it resulted in increased residence time in the
clarifier. (The normal residence time of juice in the clarifier is 2.58 hours.)
10
Analysis of cost:
The reduced throughput that was required to reduce the juice flow to the clarifier resulted
in the need to supplement power generation to the plant. Wood and labour (woodmen
required) and increased diesel usage resulted.
ORGANIC SUGAR – PROCESSING COST
A
Cleaning for Organic Sugar Production
Labour
Material
B
Labour Cost for operating on Shift
Labour
C
Chemical Usage
Materials (Lime – 0.750 kg/ton cane)
D
Building of Storage Bond
Labour/Contractor
Materials
E
Sealing above Storage Bond
Labour
Materials
F
Molasses Pipes – Storage
Labour
Materials
G
Fuel
Wood
Diesel
Amount G$’000 Amount US$
1,934.00
917.00
2,851.00
$15,005.00
1,578.00
1,578.00
$8307.00
368.00
368.00
$1937.00
254.00
150.00
404.00
$2125.00
138.00
106.00
244.00
$1284.00
376.00
1,000.00
1,376.00
$6716.00
1,800.00
3,176.00
4,976.00
$26,189.00
Grand Total
6,821.00
US $ 61,563.00
Discussion and conclusion
11
The clarification process was the major processing constraint during organic sugar
production. There was some carryover of mud in clarified juice leading to sugar with high
colour and insoluble solids. With current operation, we would not able to produce sugar for
direct consumption. However, there is potential to sell this to organic food manufacturers
where the sugar is re-processed.
From a financial point of view, we must examine the feasibility of this endeavour.
Practically to produce organic sugar, the factory must first lower throughput / reduce juice
flow to the clarifier, and slow or even halt grinding to allow for settling of muds. A similar
situtation occurred in 1980 at Uitvlugt estate, no flocculant was used and the factory
throughput was 90 tonnes per hour and grinding was intermittent to allow for settling. For
organic sugar production, additional cost is incurred due to increase fuel demand, and
increased labour costs.
For expansion in production, organic sugar quality must be improved i.e. meet standards
for direct consumption, the clarification process must be improved, or employ a process
whereby the final product can be refined. Natural sources can be examined for potential
flocculants; for example, Moringa oleifera (commonly called drumsticks, ‘saijan’) is known
to have clarifying properties. Capital input is required for improving sugar quality; a rotary
DSM screen would reduce the amount of solid impurities in mixed juice, while a sugar
dryer would enhance keeping quality of the sugar.
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GENUINE DEMERARA ORGANIC CANE SUGAR
SOIL ASSOCIATION APPROVED
PRODUCED UNDER ORGANIC STANDARDS
A PRODUCT OF GUYANA
NET WT. 25 Kg. (55 lbs)
Date Manufactured: August 2003
References
1. Soil Association Certification Limited – Inspection Report (based on Inspection date
11/02/2003) by Jerry Harding.
2. Inter Estate Research General Manager, ICBU/Agriculture Director, Dr. Harold
Davis 15/08/2000.
3. Soil Association Certification Limited - Inspection Report Processing and
Packaging – Henry Lung Kit, Technical Manager.
4. Notes from Organic Sugar Seminar (July 2003) – Henry Lung Kit, Technical
Manager
13
List of Tables
Table 1: Organic sugar specifications from a prospective customer.
Table 2: Table 2: Cost – Organic Cane Cultivation, G $’000
List of Charts
Figure 1: Organic cane ground during period 9/8/03 - 16/08/03
Figure 2: TCH for Organic Cane ground 9/8/03 - 16/8/03
Figure 3: Purity profilie of mixed juice
Figure 4: pH profile of Limed Juice, Mixed Juice and Clarified Juice
Figure 5: Daily turbidity values for Clarified Juice
Figure 6: Colour of Daily Composite Sugar Samples
Figure 7: Insoluble solid in Daily Composite Sugar Samples
Figure 8: Chart showing AGT and Out of Cane Periods
Figure 9: Field Cost for the period 2001 - 2003
Figure 1: Organic cane ground during period 9/8/03 16/08/03
Tonnes cane ground
2500
2000
1500
1000
500
0
9/8
10/8
11/8
14/8
15/8
16/8
Date
14
Figure 2: TCH for Organic Cane ground 9/8/03 - 16/8/03
120
Average TCH
100
80
60
40
20
0
9/8
10/8
11/8
14/8
15/8
16/8
Date
Figure 3: Purity profilie of m ixed juice
82.00
81.00
Purity
80.00
79.00
78.00
77.00
76.00
75.00
74.00
73.00
72.00
9/8
10/8
11/8
14/8
15/8
16/8
Date
Daily averages
Figure 4: pH profile of Lim ed Juice, Mixed Juice and
Clarified Juice
10.00
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Limed Juice
M ixed Juice
Clarif ied Juice
9/8
10/8
11/8
14/8
15/8
16/8
Date
15
Figure 5: Daily turbidity values for Clarified Juice
45
40
Turbidity
35
30
25
20
15
10
5
0
9/8
10/8
11/8
15/8
16/8
Date
Figure 6: Colour of Daily Com posite Sugar Samples
4000
3500
Colour, icu
3000
2500
2000
1500
1000
500
0
17/8
19/8
20/8
21/8
Date
Insoluble solids/ ppm
Figure 7: Insoluble solid in Daily Composite Sugar
Sam ples
1000
800
600
400
200
0
17/8
19/8
20/8
21/8
Date
16
Figure 8: Chart showing AGT and Out of Cane Periods
30
25
Hours
20
AGT/hrs
15
Out of Cane/ hrs
10
5
0
9/8 10/8 11/8 12/8 13/8 14/8 15/8 16/8
Date
Figure 9: Field Cost for the period 2001 - 2003
8000
7000
5000
4000
3000
2000
1000
W
ee
d
Activity
th
er
s
PL
O
LG
Pr
ep
C
on
tro
C
l
om
po
st
in
g
H
ar
ve
st
Pl
an
t in
g
D
ra
in
ag
e
0
La
nd
Cost G'
000
6000
2001
2002
2003
17