to - the Institute of Masters of Wine

1/27/2014
Physiology and Psychology of
Flavor Perception
Flavor is the psychological interpretation of the
physiological response to a physical stimulus*
Hildegarde Heymann
University of California at Davis, USA
January 25, 2014
Flickr: Like_the_Grand_Canyon
Flickr: Libraryman
Blog: Reasonably Well
*Also affected by vision
A range of senses are used when tasting wine.
Normal human physiological
variation
These senses are:
• sight
• taste
• smell
• touch
•[hearing]
Flickr: Mike McCaffrey
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Appearance
• First impression
• Color – many expectations
The Nature of Color
http://imaginehearts.files.wordpress.com/2013/06/color‐is‐in‐the‐eye.jpg
http://winefolly.com/wp‐content/uploads/2012/02/color‐of‐wine‐primary‐indicators.jpg
Color is the absence of (certain)
wavelengths
http://image.wistatutor.com/content/feed/u1006/eye%20image.jpg
http://1.bp.blogspot.com/‐‐gCW5gTCzJo/TxVIH‐fUIGI/AAAAAAAAH9Y/67mYZRvpbP4/s1600/seeing+colours.jpg
Rods (scotopic vision):
abundant in periphery, dim light, B/W
Cones (photopic vision):
abundant around fovea, bright light, color,
http://cs.fit.edu/~wds/classes/cse5255/cse5255/davis/rod_cone.gif
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Different types of opsins:
Exact structure of opsin molecule determines maximal
sensitivity to lights wavelengths
COLOR-BLINDNESS
Ishihara Plates
– Long wavelength: red light
– Medium wavelength: green light
– Short wavelength: blue light
Molecular Expressions: Optical Primer
http://www.diycalculator.com/sp‐cvision.shtml
5-8% of males (as high as 1 in 12)
0.5% of females (1 in 200)
Normal human color vision
variability
 Rayleigh color test
 use red & green lights to make yellow
 Opsin polymorphic variant at amino acid 180
 60% of red pigments encode for serine
 40% of red pigments encode for alanine
▪ ser version is red shifted 3-4 nm relative to ala
▪ i.e. they need less red light to match the yellow
 90% of green pigments encode for ala
 10% of green pigments encode for ser
Y = tyrosine, T = threonine, A = alanine, I = isoleucine, S = serine, F = phenylalanine
Vision Research (2011) volume: 51 issue: 7 page: 633‐51
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Individual variation of Just Noticeable Differences at isoluminance (8 women; 2 men)
Taste versus “taste”
100
with smell
90
Without smell
80
Percent correct
70
60
50
40
30
20
10
0
Water
Vinegar
Whiskey
Wine
Coffee
Chocolate
Garlic
Substance to be identified
Journal of Vision June 3, 2013 vol. 13 no. 7 article 1
Taste
• Five “basic” tastes
sweet, salty, sour, bitter, umami, [fat, water]
• Oral Sensations: (Chemestesia)
astringency, burn/irritation, tingling, temperature
Compounds must be dissolved (saliva, wine, etc.) Taste
• final "barrier" function – intimate contact – least complicated – stimulation to perception time is very short
•
•
•
•
Taste: 1.5 – 4.0 msec
Touch 2.4 – 8.9 msec Vision: 13 – 45 msec Hearing: 13 – 22 msec http://drinkcharitably.com/spitting-wine.jpg
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Hänig’s 1901 dissertation and the tongue map – a story about primary resources
Sweet, sour salty – not much difference
Bitter – back of palate (mostly due to soft palate taste buds)
www.musingsonthevine.com
NY Times, 11/10/08: Leif Parsons
Bartoshuk, L.M. (1993). The biological basis of food perception and acceptance. Food Quality and Preference, 4, 21‐32
Purvis et al. (2001) Neuroscience, 2nd edition
Infant Taste Responses
sweet
sour
bitter
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“Supertasters” ‐Hypertasters
• PTC (phenyl thio carbamate)
• PROP (6-n-propylthiouracil)
• H-N=C-S group
• Sensitivity genetic
• Chromosome #5 (with some effect from #7)
• May have had evolutionary advantage:
• Plants high in H-N=C-S group tend to contain
toxic elements
• Protects against goitre (iodine deficiency)
“Supertasters” continued
•Dye tongue blue
•Count papillae in
reinforcement circle at tip
•<20: nontaster
•>40: supertaster
With thanks to JX Guinard
“Supertasters” continued
PROP (propylthiouracil) thresholds
PROP thresholds for 41Ss
1.E-03
1.E-03
X= 1.14 E-5
std=1.08 E-5
(n=21)
1.E-03
X=1.23 E-4
std= 1.96 E-5
(n=10)
X=1.83E-4
std 3.75 E4
(n=10)
8.E-04
6.E-04
4.E-04
2.E-04
0.E+00
1
supertaster
nontaster
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
Supertaster
Taster
Non-taster
http://blogsoop.com/blog/wp‐content/uploads/2007/07/supertasters_nontaster.jpg
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Bitterness, sweetness, and liking ratings of unsweetened white grapefruit juice.
“Supertasters” continued
• US population
• 25% ST, 50% MT; 25%T
• 35% of woman and 10% men
• Asians higher proportion ST
Hayes J E et al. Chem. Senses 2011;36:311-319
© The Author 2010. Published by Oxford University Press. All rights reserved
Bitterness and trigeminal effect of 10% ethanol
(Bartoshuk et al. 1994)
Bitterness
Burning/
Hotness
OLFACTION
Intensity
Non tasters
Nicht
Schmecker
Schmecker
Tasters
Super
Supertasters
Schmecker
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Olfactory Cells
•
•
ORTHO and RETRO NASAL OLFACTION
Retronasal smell images are IMPORTANT as illustrated by the massive extent to which they interact with these brain systems compared with orthonasal smell images
Olfactory Mucosa
– orange-yellow pigment area
(2.5 sq. cm)
– cilia area -- 6000 sq. cm
Olfactory cells
– Very sensitive
• mercaptans
– 40 olfactory cells need
9 molecules each
– 10 million cells
– Lifespan -- 30 days
– axons directly to olfactory bulb
no synapses!
Aging declines in flavor perception: Retronasal olfaction is more vulnerable to loss than orthonasal olfaction
Anosmia
Odor molecules create different patterns of spatial activity in the olfactory bulb. A homologous chemical series (aldehydes) elicits patterns that are overlapping but different, as shown high‐resolution functional magnetic resonance imaging (fMRI)
Olfactory cell axons pass through cribiform plate Viral infections
Gordon M. Shepherd, Nature 444, 316‐321(16 November 2006)
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Nasal cycle
•
•
•
•
Scent tracking by humans
(Noam Sobel UCB)
80% of humans have a nasal cycle lasts 30 min to 5 hours (mean 2‐2.5 hours)
combined flow rate remains constant
Odorants attachment to mucosa depends on airflow
– Some better at low versus high and vice versa • Provides two olfactory images of the world
– Result: better olfactory acuity
Porter, et al., (2007) Mechanisms of scent-tracking in humans, Nature Neuroscience 10, 27 - 29
http://www.sleep‐apnea‐prevention.org
Aroma: Specific anosmias
Specific Anosmia Observed for β-Ionone,
but not for α-Ionone
 Good sense of smell BUT much less sensitive (at least 100 fold less)
 40 of 62 compounds at least 4% of population (Amoore, 1969)
 androstenone (about 5%)  OR7D4 receptor genes
 Both copies: urine and unpleasant
One copy: no or weak odor
 Mutation in gene: floral and pleasant
 Compounds at 30+% 




isobutyraldehyde – malty
geraniol ‐‐ rose‐like odor
Pentadecalactone ‐‐ musky
musk xylol ‐‐ musk odor
1,8‐cineole ‐‐ camphoraceous
Frequency distribution of β-ionone,
and α-ionone orthonasal thresholds
in water and deodorized orange juice
(pumpout).
Concentrations in water or pumpout
for steps 1, 6, and 12 are indicated
below each compound, accordingly.
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Tempere et al. (2011) The Training Level of Experts Influences their Detection
Thresholds for Key Wine Compounds. Chem. Percept. (2011) 4:99–115
3‐methoxy‐2‐isobutylpyrazine
Aroma
Carvone
• Thousands of odors
• “Tip of nose” phenomenon
3‐methoxy‐2‐isopropylpyrazine
musk odors == entirely different families
http://mappery.blogspot.com
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Chemical irritation
“Common chemical sense” or chemesthesia
– Free endings of the trigeminal aka 5th cranial nerve
– CO2 (tingle), capsaicin (burn), mustard (pungency), bite (raw onion), astringency (tannin),
pain (chlorine)
Dr Spiller.com
• Often innate dislike (protection) but can be overcome and be pleasurable
Astringency of 4 tannic acid samples (1.4 g/L) rated by LR (20), MR(37) and HR(20) subject groups
Questions?
“We live in our own sensory world –
individual differences in sensory
functioning … even with simple aromas
and flavors … will not be similarly
perceived as acceptable”
R=Salivary responsiveness, Low, Medium, High
Dinella et al., 2011, Chemical Senses
Mela, D. Prepared Foods, July, 1996
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