Sensory Panels & Perception of Taste and Flavour Methven.pdf · Hydrogen sulfide Rotten eggs 0.18...

© University of Reading 2008 www.reading.ac.uk

Department of Food and Nutritional Sciences

09 March 2015

Sensory Panels & Perception of Taste and Flavour Dr Lisa Methven

Sensory Science Centre,

Department of Food and Nutritional Sciences

University of Reading, UK

Dr Lisa Methven : Dept Food & Nutritional Sciences

Overview:

2

• How do we Perceive Flavour ?

• Sensory Panels and Consumer Panels • The differences between the two

• Why do both ?

• Previous Herb study using Sensory Profiling panel • Basil & Coriander over shelf life

• Study of plant diversity & sensory effects • Lettuce: using consumer perception on logarithmic scales

• Relating flavour chemistry to sensory data: an example of Melons

• Impact of Individual perception

• Using sensory to promote wider use of Herbs & Spices


How do We Perceive Food ?

• Taste

• Smell

• Chemesthesis

• Vision

• Touch

• Sound

Respond to chemical stimuli. Contribute together to flavour perception

Cranial Nerves : emerge directly from the brain (not from spinal chord)


What is Flavour ? Taste + Aroma

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Taste Aroma

Receptors: On the Tongue ! ~ 6000 taste buds - located in papillae - different receptor types in each taste bud; ion channels & G-proteins

Receptor : In the Nose ! - orthonasal & retronasal - 6-10 M olfactory cells in olfactory epithelium - G-protein receptors

Stimulus : Dissolved Non-Volatiles - ionic or organic - water soluble

Stimulus : Airborne Volatiles -combinations of volatile molecules - lipophilic, organic - recognise and memorise ~ 10,000 aromas

Thresholds : mg/L (bitter) - g/L (salt & sugar) Thresholds : ng /L - µg/L (ppm, ppb or lower)


Taste

• Physical Stimulus = Dissolved Non-Volatiles

• Basic Tastes : – Salt – Sour / Acid – Sweet – Bitter – Umami

• Considered to also include – Metallic Taste – Astringency – Fatty acid taste receptors – Thermal tasters

ionic

organic


Anatomy of Taste System

Taste bud cells end in microvilli which make contact with fluid environment in mouth through a taste pore at the top of the taste bud

At other end, synapses with nerve

fibres


Enhancement and suppression

• Tastes usually suppress each other

• Taste and Aroma’s can enhance or suppress

• Usually at the cognitive level (ie it’s all in your mind !)

• Umami (savoury) compounds enhance each other

– Act synergistically at the receptor level

Dr Lisa Methven : Dept Food & Nutritional Sciences 8

What about Aroma Perception ? : ortho & retronasal

Orthonasal Retronasal

Olfactory

epithelium


Anatomy of Olfactory System


Odour Thresholds

• Far lower absolute thresholds than for taste

– ~ 10,000 times more sensitive

• Poorer ability to discriminate intensity levels

– differential thresholds are high, 15-20 % concn change needed to detect a difference

• Thresholds related to physical & chemical properties

– (e.g. volatility, phase partition, solubility)

• Anosmias : inability to detect families of similar smelling cpds.

– E.g. Androstenone (boar taint), cineole (terpene in herbs), diacetyl (butter like), trimethyl amine (fish spoilage)


Odour Thresholds

Compound Odour Quality Threshold (μg/l air)

Methyl salicylate Wintergreen 100

Amyl acetate Banana 39

Ethyl acetate Pineapple 36

Butyric acid Rancid butter 9

Pyridine Burnt, smokey 7.4

Safrol Sassafras (woody-floral) 5

Benaldehyde Almond 3

Hydrogen sulfide Rotten eggs 0.18

Courmarin Haylike, nutlike 0.02

Citral Lemon 0.003

Methyl mercaptan Rotten cabbage 0.0002

bis(2-methyl-3-furyl)-

disulfide

meat-like, roasted 0.00002


Chemesthesis : Chemical irritation or Trigeminal perception

• Chemesthesis is the term used to describe the detection of chemical irritants

• Perceived in the eyes, nose and mouth • Primary function = protect the body from noxious

chemical stimuli • Trigeminal sensations refer to burn from hot pepper,

pungency from mustard, cooling of mint etc.

• Involves TRIGEMINAL nerves • 3 branches: 1. Ophthalmic (to eyes) 2. Maxillary (to nose) 3. Mandibilar (to mouth)


Sensory Science

The Science of our 5 senses: - What we perceive - How we measure what we perceive

• Vision • Hearing • Aroma (ortho & retro) • Taste • Chemesthesis • Mouthfeel

• Threshold Testing • Intensity Testing • Discrimination Testing • Profiling

Perception Measurement


Consumer Science

Possible Solutions :

1. Central Locations Trials (CLTs) Can be inappropriate environment No Product knowledge built up

2. Questionnaires

• Home Use Trials. Issues of Compliance Lose cost / benefit equation

• Test Market

Observing “natural” behaviour without influencing it is very tricky !


It’s not all about liking….but we do measure liking a lot ! Do you always want what you like ??!

Consumer Science

Thomson Matrix of Brand Equities


Previous Studies on Herbs: Basil & Coriander change over Shelf Life

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• Sensory Profiling panel used as describing & quantifying all attributes was needed

• Trained panel (n=12) at SSC

• Vocabulary developed:

• 49 attributes for Basil leaves • 5 differed significantly over shelf life

• 37 attributes for Basil pesto • 4 differed significantly over shelf life

• 34 attributes for Coriander leaves • 7 differed significantly over shelf life

• 27 attributes for Coriander pesto • 7 differed significantly over shelf life


Plant Diversity & Sensory Effects : An example of Lettuce

• PhD Student: Dr Martin Chadwick

• Bitterness & health benefits from SLs (Sesquiterpenoid lactones)

• Sweetness from sugars


Consumer Perception of Lettuce Lines

• Consumers (n=43) rated liking on 9point scale

• Rated intensity of basic tastes (bitter & sweet) on labelled magnitude scales (LMS)

• The idea of these logarithmic scales is that they closely resemble true perception over increasing intensity

like extremely

like very much

like moderately

like slightly

neither like nor dislike

dislike slightly

dislike moderately

dislike very much

dislike extremely


Perception of sweet ≠ sugars

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0.4

0.5

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0.7

0.8

0.9

1.0

0 100 200 300 400 500

Log

of P

erce

ived

Sw

eetn

ess

Fructose Content (µg/g dry weight)

Fructose vs Perceived Sweetness

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0.4

0.5

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0 500 1000 1500 2000

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Total Sugar Content (µg/g dry weight)

Total Sugar vs Perceived Sweetness

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eetn

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Sucrose Content (µg/g dry weight)

Sucrose vs Perceived Sweetness

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0.5

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0.8

0.9

1.0

0 200 400 600 800

Log

of P

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Sw

eetn

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Glucose Content (µg/g dry weight)

Glucose vs Perceived Sweetness

A

C D

B

RIL61: lowest levels of fructose, yet the highest perceived sweetness

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0.4

0.5

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1.0

0 500 1000 1500 2000

Log

of

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rce

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d

Sw

ee

tne

ss

Sucrose equivalent (µg/g dry weight)

Expected Sweetness vs Perceived Sweetness

E

Sucrose equivalents = 1.73xFrc + 1x Suc + 0.74 Glc


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61

89

94

121

122

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0.8

0.9

1.0

1.1

1.2

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0 2 4 6 8 10

Log

of

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Bit

tern

ess

Lactucin Content

Lactucin vs Perceived Bitterness

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89

94

121

122

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0.8

0.9

1.0

1.1

1.2

1.3

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0 5 10 15 20

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tern

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Lactucopicrin Content

Lactucopicrin vs Perceived Bitterness

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61

89

94121

122

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0.8

1

1.2

1.4

1.6

1 10 100

Log

of

Pe

rce

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tern

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8-deoxylactucin-15-oxalate Content (log scale)

8-deoxylactucin-15-oxalate vs Perceived Bitterness

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89

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0.80.91.01.11.21.31.41.51.6

0 10 20 30 40 50

Log

of

Pe

rce

ive

d

Bit

tern

ess

8-deoxylactucin-15-oxalate Content

Lactucopicrin-15-oxalate vs Perceived Bitterness

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89

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1.0

1.2

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Log

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tern

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Lactucin-15-oxalate Content

Lactucin-15-oxalate vs Perceived Bitterness

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89

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0.8

0.9

1.0

1.1

1.2

1.3

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1.6

0 100 200 300 400 500

Log

of

Pe

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Total SL Content

Total SL vs Perceived Bitterness

A B

C D

E F

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0.80.9

11.11.21.31.41.51.6

0.05 0.5 5 50

Log

of

Pe

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tern

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15-p-hydroxylphenylacetyllactucin-8-sulphate Content (log scale)

15-p-hydroxylphenylacetyllactucin-8-sulphate vs Perceived Bitterness

G

SL content correlates to bitter perception…but with exceptions

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122

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0.8

0.9

1.0

1.1

1.2

1.3

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Log

of

Pe

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ive

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Bit

tern

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Lactucin Content

Lactucin vs Perceived Bitterness

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61

89

94

121

122

123

0.8

0.9

1.0

1.1

1.2

1.3

1.4

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Log

of

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Lactucopicrin Content

Lactucopicrin vs Perceived Bitterness

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61

89

94121

122

123

0.8

1

1.2

1.4

1.6

1 10 100

Log

of

Pe

rce

ive

d

Bit

tern

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8-deoxylactucin-15-oxalate Content (log scale)

8-deoxylactucin-15-oxalate vs Perceived Bitterness

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41

61

89

94

121122

123

0.80.91.01.11.21.31.41.51.6

0 10 20 30 40 50

Log

of

Pe

rce

ive

d

Bit

tern

ess

8-deoxylactucin-15-oxalate Content

Lactucopicrin-15-oxalate vs Perceived Bitterness

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41

61

89

94

121

122

123

0.8

1.0

1.2

1.4

1.6

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Log

of

Pe

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d

Bit

tern

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Lactucin-15-oxalate Content

Lactucin-15-oxalate vs Perceived Bitterness

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61

89

94

121

122

123

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

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0 100 200 300 400 500

Log

of

Pe

rce

ive

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tern

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Total SL Content

Total SL vs Perceived Bitterness

A B

C D

E F

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0.80.9

11.11.21.31.41.51.6

0.05 0.5 5 50

Log

of

Pe

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ive

d

Bit

tern

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15-p-hydroxylphenylacetyllactucin-8-sulphate Content (log scale)

15-p-hydroxylphenylacetyllactucin-8-sulphate vs Perceived Bitterness

G

RIL122: high levels of SLs, but not perceived as very bitter.


Sweetness Suppresses Bitterness Sugar: SL Ratio regulates perception and liking

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123

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

0.4 0.5 0.6 0.7 0.8 0.9 1.0

Lik

ing

Sco

re

Log of Perceived Sweetness Intensity

Sweetness vs Liking

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3.0

3.5

4.0

4.5

5.0

5.5

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6.5

7.0

0.8 1.0 1.2 1.4 1.6 1.8

Lik

ing

Sco

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Log of Perceived Bitterness Intensity

Bitterness vs Liking

A B High SL, low sugar

Low SL, low sugar

High SL, high sugar


Relating flavour chemistry to sensory data: an example of Melons

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Melon Study:

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• Flavour profiles of 2 genotypes of cantaloupe melons • Harvested mature & immature • Volatiles by 2 methods (Dynamic headspace & SPE) • Sensory by Profiling panel • Lots of data ! : Sensory means correlated with

instrumental data via Multifactor Analyis (MFA)


Multifactor Analysis (MFA)

• Use when you want to simultaneously analyse several

different types of data tables

• Within a table the variables must be the same type; but

the tables can be of different types

• Here:

– Sensory Data with 20 significant variables;

– Volatile data with > 100 variables

– Other Chemical data of 10 variables

– If you just put this into PCA then volatile data will dominate

– So use MFA

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Melon Study MFA:

26


Melon Study conclusions from MFA:

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• Sensory analysis linked well with instrumental data • Mature MSL fruit positively correlated with factor 1:

• sweet (o01), honey (o02), floral (o03) & strawberry (o04) odours and floral (tf06), honey (tf07), strawberries (tf09) & ripe tropical fruit (tf19) taste/flavour terms.

• These variables were highly positively correlated with the majority of the esters.

• Immature iMSL fruit negatively correlated with factors 1 & 2: • all cucumber and green notes (o07, o08, tf12, tf13), &

acidic after-taste (ae04) • compounds like (Z)-6-nonenal (e06) and two methyl

esters (a01& b01) positively correlated with iMSL


What’s the relevance of individual differences in sensory perception ?

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Taste

• Number of Receptors

• Genetic Differences in Taste Receptors

Mouthfeel •Number of Papilla

Aroma

• Genetic differences in Olfactory Receptors Anosmia or Flavour Quality

• Number of functioning olfactory cells


“Super” and “Non” Tasters

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Genotype

•TAS2R38 (Bitter receptor)

•CA6 (Gustin; influences number of papilla & taste cells)

Phenotype

SUPERTASTER:

•Densely packed papillae

•All Tastes more Intense

•Can taste bitter thiourea groups (PROP & Brassica)

•Mouthfeel more intense

• Spicy more intense

Choice & Diet

• May avoid bitter foods and alcohol

• May avoid creamy mouthfeel foods

• May avoid intensely sweet or fatty foods

• May avoid brassica veg


• Genetic bitter blindness to compounds with a thiourea group (N-

C=S), such as PROP (6-n-propylthiouracil) and PTC

(phenylthiocarbamide)

• Genotype of one bitter GPCR receptor (hTAS2R38)

• hTAS2R38 effects how GLUCOSINOLATE containing vegetables

(BRASSICA) taste

“Nontasters” :

OR

N

OSO3

SOH

OH

OH

OH

-


Effect of Taster Status on Perception, Liking and Intake (Yuchi Shen)

• UK Volunteers (n=151)

• TAS2R38 & Gustin

• Papillae Density

• Vegetable Perception, Liking and Intake

31


Liking & Bitter Intensity data…

Also completed Food Frequency questionnaires (FFQ)

9 Like extrmely

8 Like very much

7 Like moderately

6 Like slightly

5 Neither like or dislike

4 Dislike slightly

3 Dislike moderately

2 Dislike very much

1 Dislike extrmely

9-Point Hedonic Scale

Brassicavegetables

(BVs)

Green

Broccoli

Non-green

Whitecabbage

Non-brassica

vegetables(non-BVs)

Green

Spinach

Non-green

Courgette(withoutskin)


Bitter intensity & Liking

0

5

10

15

20

25

30

35

Broccoli WhiteCabbage

Spinach Courge e

Bierintensity(An

-log)

PAV/PAV

PAV/AVI

AVI/AVI

BV were perceived as more bitter

than non-BV (p=0.0002)

PAV/PAV (p=0.006) perceived

significantly stronger bitter intensity

from BVs.

5.0

5.2

5.4

5.6

5.8

6.0

6.2

6.4

6.6

Broccoli WhiteCabbage

Spinach Courge e

Likingoftaste

PAV/PAV

PAV/AVI

AVI/AVI

• However, a trend that insensitive groups

(AVI/AVI) showed higher liking of taste

compared to sensitive groups (PAV/PAV)

• Similar trend also found in PROP taster

status, and FPD groups


Using Sensory to Promote Wider use of Herbs … or Using Herbs to promote dietary change

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The potential to use Herbs & Spices to

reduce salt in food but maintain liking


A Fresh Herb Soup example

• Our 1st study used soup : Carrot &

fresh Coriander

• Initial Liking : standard commercial salt level (0.22 %Na w/w) compared to 0, 0.11, 0.17, 0.28 & 0.34 %w/w)

• Liking tended to Increase with Salt Level

• However, only the 0 %Na was significantly less liked than standard (n=40)


Liking over Repeat Exposure

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8

He

do

nic

Lik

ing

exposure days

Group-Con

Group-Exp

• The group divided into 3

• Each received one soup every day for 8 days :

• control, 0.28 % w/w Na (small portion)

• exposure, 0 % Na (small portion)

• nutrient learning, 0 % Na (full bowl)

• Significant Increases in liking with exposure days as follows :

• At Day 3 for Exposure group

• At Day 5 for Nutrient Learning Group


After the Repeat Exposure

• Comparing Pre- and Post- Exposure ratings:

• Overall Inc in Liking (p<0.01)

• High salt soup was preferred

• Liking of No Salt Soup had significantly increased for EXP and NUTR groups, but not for CNTL group


Using Dried Herbs in a Tomato Soup

• Tomato Cup of Soup:

– Developed standard commercial salt level (0.57% w/w) plus lower salt variants (0.26% w/w; 53% reduction)

– Developed 3 H&S modifications at low salt level

• Liking of the 3 S&H modifications : to determine the H&S modification to progress

• Pre- and Post Exposure

– Liking of low salt Herb Soup compared to Std and Low salt control with NO HERBS

– Exposure Period (3 consecutive days)

– 3 groups of n=50, each consume 1 food per day (Std or LSC or H&S)

– Liking scored each day and volume consumed recorded


Initial Liking of the Low Salt H&S Mods Liking (n=150) on VAS scale; 4 tomato soup samples prepared

with different S&H modifications

Overall liking

Liking of appearance

Liking of taste Liking of texture

Oregano, Bay and Black Pepper (0.3% salt in soup)

57a 57a 56a 57a

Basil, Black pepper & Celery (0.3% salt in soup)

55a 58a 53a 56a

Cumin & Coriander (0.3% salt in soup) 54a 60a 53a 56a

No significant difference in any variant, but….


…people like different things

Cluster analysis :

Oregano progressed (had highest mean liking score by a large cluster)

Mean liking of each cluster

Cluster N (%) in

cluster

Basil & Bay Coriander &

Cumin

Oregano &

Bay

1 56 (37%) 65 58 42

2 41 (27%) 36 68 58

3 53 (35%) 57 42 72


Liking Increased During Exposure


Liking for Oregano Mod Increased pre- to post exposure


Take home message…

• We can use Herbs to reduce salt level desired in foods

• …but many consumers need to learn to like it !


Conclusions

• Plant genetics can effect availability of phytochemicals, and so flavour

compounds, sensory perception & consumer liking

• There are lots of sensory methods available to use depending on your

question:

– Untrained assessors can tell you if there is a difference (n>60)

– They can also rate tastes well (LMS scales)

– Consumers can tell you what they like (n>100)

– Trained sensory panels can describe & quantify all differences

• Some like it hot…and some do not !

– Individual differences in sensitivity to bitter and heat

– Maintaining bitter compounds but increasing sugars can increase acceptability


Acknowledgements

Sensory panellists PhD Students Dr Carol Wagstaff Dr Jane Parker Dr StellaLignou

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Thank you

Any Questions ?

Sensory Panels & Perception of Taste and Flavour Methven.pdf · Hydrogen sulfide Rotten eggs 0.18...

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