WP2 Sensory Analysis Presentation

Methodological Report

WP2 Sensory Analysis Presentation Nelly FORESTIER-CHIRON, CIRAD, Montpellier, France

Christophe BUGAUD, CIRAD, France Isabelle MARAVAL, CIRAD, France

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This report has been written in the framework of RTBfoods project.

To be cited as:

Nelly FORESTIER-CHIRON, Christophe BUGAUD, Isabelle MARAVAL. 2018. WP2 Sensory Analysis Presentation. Montpellier (France). RTBfoods Project Report, 80 p.

Image cover page © Dufour D. for RTBfoods.

© D. Dufour

Sensory analysis

[email protected]

Nelly Forestier-Chiron

Christophe Bugaud

Isabelle Maraval

© D. Dufour

Quality

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Quality

Ability of a product to satisfy its users

Food quality has multiple components:

- Safety / hygiene & sanitary quality- Health / nutritional quality- Taste / organoleptic quality- Service / quality for use

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© D. Dufour

Plan

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Plan

I. What is sensory analysis: perception and measurement Some definitions Physiology of perception Sensory response

II. The various types of sensory tests Analytical (discriminative, descriptive) Hedonic

III. Drawing up a sensory profile: descriptive tests The working environment: the laboratory The panel Drawing up the protocol Preparing the questionnaires

IV. In practice ... Setting up a panel Recruitment General training Specific product training 5

Plan





© D. Dufour

PART I

What is

sensory

analysis:

perception

and

measurement

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I. What is sensory analysis:

perception and measurement

TOUCH

SMELL

SIGHTHEARING

TASTE

Sensory analysis is defined by ISO as the examination of theorganoleptic properties of a product by means of the sensory organs

= defining a relationship between stimulus and sensory perception

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Visual

stimuli

Auditory

stimuli

Olfactory

stimuli

Gustatory

stimuli

Tactile

stimuli



Shape (flat, round, etc.) Colour (yellow, dark, etc.)State (Liquid, Solid, Gaseous, etc.)Appearance (clear, cloudy, dull, shiny,etc.)

Softening, crunchiness, etc.

Volatile, spicy, floral substances, etc.

Primary tastes (sweet, salty,sour, bitter)Impressions / sensations (astringent,spicy, metallic, etc.)Aroma (fruity, floral, etc.)

Consistency, temperature, spongy, etc.→ Fruit maturation stage, cooked meat,etc.

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Chewing rear nasal

+ saliva



Some definitions (ISO)

Odour : emanation of volatilesubstances perceptible to(front nasal route)

the olfactory organ

Aroma : perceptible to the olfactory organ (rear nasal route) during tasting

Taste : sensations perceivedby the gustatory organ whenstimulated by certain solublesubstances

food in mouth

expulsion of volatile olfactorycompounds from matrix route cavity

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Astringency : qualifies the complexsensation resulting from contraction of thesurface of the mouth's mucous membranes,produced by substances such as tannins frompersimmon, wine, etc.

TASTE

Flavour : complex set of olfactory and taste sensations perceived during tasting

AROMA

ODOUR

FLAVOUR



Some definitions (ISO)

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Taste perception

Diagram of the tongue



Tactile sensitivity

Fungiform papilla

Filiform papilla

Calciform papilla

Bitter

Salty

Sweet

Sour

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Tastes: examples



• Sour : tartaric or citric acidLemon, orange, coca cola

• Bitter : caffeine or quinine hydrochlorideEndive, dark chocolate, coffee

• Salty : sodium chlorideCrisps

• Sweet : sucrose Sweets

The detection and recognition thresholds depend in particular on

dietary habits and training 14

Odorant

substances:

examples



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A scientific method!

The objective: define a relationship betweenstimulus and sensory perception

Not measurable by other methods

There is no standard observer

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What is it used for?

Research and development (formulation, comparison, development of new products, brand strategy, etc.)

Comparing qualitative and quantitative information

Quality control

Marketing / Consumer preferences

Guiding research

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Receptors Nerve fibres Brain

stimulation Conscious ResponseBehaviour



Physiology of perception

A FOOD emits a variety of information perceived bythe sensory organs:

these are STIMULI

Each sensory organ transforms a stimulus into a NERVE

IMPULSE which travels via the corresponding sensorynerve to be interpreted in the BRAIN

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Physiology of perception

1. Coding (quality, intensity)2. Integration: hedonic score (memory)3. Emotional + sensory message4. Verbalisation, quantification, aversion, preference

Sensory response

Spontaneously:1. Hedonic comment2. Qualitative comment3. Quantitative comment

Need for training to describe correctly, precisely and reproducibly 19

Sensory response



The intensity of the sensation is a function of themagnitude of the stimulus

1 : subliminal, background noise

2 : liminal, unpredictable sensation (clear / confused), very low intensity

3 : supra-liminal, clear sensation, intensity varying from“weak” to “strong”

4 : saturation, sensation with practically no variation (possibility ofdiscomfort)

Value of stimulus

Inte

nsi

ty o

f se

nsa

tio

n

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Psychological factors:- Appearance: pink-coloured yogurt, coloured white wine,brand, etc.

- Influence from neighbour: grimace- Sample presentation order (1st product)- Character (hesitant use of scale) fair

= good

fair= indifferent



Sensory response

- Information on study

Sensory response is influenced by:

Physiological factors:- Ageusia, etc.- Persistence

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Sensory response

This is an interaction between the experimenter and the subject

Experimenter Sensory subjectstimulus

question

The question is essential22

Plan





© P. Vernier

PART II

The various

types of

sensory tests

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II. The various types of sensory

tests

Two types of approach :

Analytical :

Discriminative or descriptive

Differences

Hedonic :

Refering to pleasant or unpleasant sensations

Preferences

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tests

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tests

“Naive” subjects: unfamiliar with either the product or sensory analysis

Informed subjects: familiar with the product and sensory analysis

Qualified subjects: familiar with theproduct, sensory analysis, trained, monitored,approved,etc.

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tests

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tests

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tests

Discriminative tests

Among the most commonly used tests: checking production consistency, consequences of a change in raw material, evaluation of modified appearance time during storage, etc.

Various types:

Duo/trio Triangular P out of nA not A

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tests


Example: Which sample do you perceive as different from the other 2?

Judge 1:

A A B

Judge 2:

A B B

Is there a difference between 2products?

Triangular test

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tests

Subjects- Around thirty- Monitor their results over time

Samples- 6 possible presentationsAAB, BAA, ABB, BAA, ABA, BAB- Use each presentation a similar number of times

otherwise risk of bias (random choice of middle sample,better identification of the most intense sample if it is doubled)

Processing:Number of correct responses and comparison with a 1/3 probability binomial distribution (cumulative probability, unilateral test)


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tests


Advantages:- Easy to implement- Easy to take, even for untrained subjects- Fun (training)- Easy to interpret

Drawbacks:- Requires homogeneous products- High number of tests if there are a lot of samples- No indication on the nature of the difference

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tests

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C < A < B

Descriptive tests

Ranking test


tests

Rank in increasing order of intensity for a specific characteristic of the samples presented simultaneously

Example: Which product is sweetest ?

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tests

Descriptive tests

Advantages :- Easy to implement (no control or reference)- Easy to understand, even for untrained subjects- Easy to interpret- Indisputable in terms of theory (according to psychologists)- Effective

Drawbacks :- All the samples must be presented at the same time

difficulty in studying storage, for example- No indication as to intensity of the differences perceived- Potentially very high number of comparisons

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Draw up a descriptive profileConventionalprofile


tests

Descriptive tests

Example: What are the organoleptic characteristics of a coffee?

Quantification of appropriate descriptors (established list or generating a list)

Objective: describe the product as briefly as possible

NB: no hedonic descriptors

Odour intensity

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Free profile


tests

Descriptive tests

Each subject creates their own vocabulary

Training is easier

Statistical processing is complex

Interpretation of results takes much longer38


tests

Descriptive tests

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Plan





© D. Dufour

PART III

Drawing up a

sensory

profile:

descriptive

tests

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III. Drawing up a sensoryprofile: descriptive tests

The working environment: the

laboratory

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The working environment: personnel(ISO 13300-1:2006)

Laboratory DirectorAdministrative and budgetary responsibility

Sensory AnalystScientific head of the analysis

Session TechnicianTechnical Manager → operational function

panel Coordinatormanages panel activities (organisation); recruits, trains and supervises the subjects

Quality Manager43


The working environment: the room(ISO V 09-105)

Principle: constant conditions, controlled to reducedisruption and the effects that psychological and physicalconditions might have on human behaviour.

Minimum set-up:- a test room for working in booths or in a group- a preparation room

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Temperature

Humidity

Uniform and controllable light

Floor, wall and ceilings easy to clean, odourless, soft and relaxing colour→ Room free from odours, ventilation

Layout preventing mutual influence (individual booths)

Silence46

The panel


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The panel

What is required of the panel?

To understand the common definition of the terms

To recognise the sensations in the product

To ensure repeatability, reproducibility and discrimination

To be sensitive48


The panel

General recommendations Be in good health, report any sickness

Avoid body odours and cosmetics

Do not smoke, eat/drink or use strong products within at least one hour before the tests

Be punctual under all circumstances

Remain silent

Read the questionnaires attentively

Rinse out the mouth as often as possible 49


The panel

Recruitment How many?

Twice as many as required for the panel(example for 10 subjects routinely, 20 selected, hence 40 recruited)

How? Selection criteria:

• Interest and motivation• Behaviour with regard to food products• Knowledge and abilities (concentration, etc.)• Health• Communication skills• Availability• Behaviour: persistent, punctual, reliable and honest50

The panel

Recruitment


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- Pre-selection: questionnaire (availability, health, etc.)

- Selection:. Laboratory presentation, sensory analysis. Testing (taste, odour, discriminative)

- General training / Performance check. Initiation of new judges. Annual training

- Specific grid training prior to testing / Performance check

The panel

Selection / Training

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The panel Performance check

III. Drawing up a sensory profile: descriptive tests

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The panel Performance checkSt

icky

Flo

ury

Firm

Sou

r

Bit

ter

Swe

et

Ast

rin

gen

t

Mo

ist

Pe

rsis

ten

ce in

th

e m

ou

th

Po

tato

Art

ich

oke

Nu

ts

Ove

rall

qu

alit

y

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III. Drawin up a sensoryprofile: descriptive tests

The panel

In the long-term …

…. it is important to accommodate and motivate the subjects

After the studies, explain how the results are to be used

Gifts or compensation

Regularly provide guidance on theirperformance

Use codes to designate the subjects, and refrain from commenting on their results as a group

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Drawing up the protocol


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Essential points of protocol


Watch out for representativeness and preservation of the sample

Presentation method: as realistic as possible, practical

Sample homogeneity: T°, quantity, contents

Choose the number of repetitions

Make the samples anonymous

Distribution in random order 58



Sample presentation

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Sample presentation

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Sample presentation

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Protocol essential points

Anonymous tasting, but explanatory feedback after the test (meeting, sheets, etc.)

Product sanitary quality check

Tasters’ consent (form, contract, etc.)

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Protocol essential points

Other than for routine tests, the protocol developmentrequires knowledge of sensory analysis but also theproduct

Must be based on standards for sensory analysis, for the product studied

We can use books or articles published on the subject

We can also work with people with a very good knowledge of the product (selector, preparers, etc.)

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Choice of scoring scale It must above all be suitable for the subjects and the

objective

In general, contains only positive numbers or zero

Scoring scales / intervals (interval equality criterion)- structured (for example 1 to 9 or 0 to 5)- unstructured (trait)

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Choice of descriptors Existing vocabulary proposed

check relevance

Created through individual and collective work by tasters

Vocabulary generated

- At least 6 subjects- Range of products to cover all the possible qualitative

differences65


Step 1: generate a large number of descriptors Step 2: select and reduce

- The descriptors must not be hedonic- The descriptors must make it possible to differentiate the products- Synonymous or overly-similar terms eliminated- We should end up with around 15-20 descriptors

Step 3: choice of references for each descriptor (stable orreproducible)

Step 4: specific training Step 5: repeatability test

Generating vocabulary:


Choice of descriptors

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Examples of descriptors:


Choice of descriptors

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Preparing the questionnaires


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Example of tasting sheets

Drawn up from information gathered (customers, panel, etc.)

Organoleptic characterisation: visual, olfactory, gustatory examination, etc., overall quality (scoring on a scale)

The taster can note down comments69



Example of tasting

sheets

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Plan





© D. Dufour

PART IV

In practise … Setting up a

panel

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IV. In practice … Setting up a panel

Recruitment

Men / Women aged 18 to 60, in-houseremuneration??contracted

Minimum: 8 people12 – 15 trained people +++

check state of health, availability, motivationquestionnaires

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General training

Basic taste and impressions recognition test

Salty / sweet ranking test

Sour / bitter / astringent perception threshold

Triangular test on a specific product common to the various countries: pure and diluted orange juice???

Odour recognition test: 4 odours (brown bottle with citrus zest / coffee grounds / flowers / fruit / spice / grass???)

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General training

If a judge makes 2 or 3 errors out of 5 tastes / impressions during the ranking and perception tests, they must retake the recognition test 1

If in test 1 they make 2 errors out of 6 responses (tastes / impressions / water), they are permanently removed from the panel

Each judge approved to remain on the tasting panel will take this general training once a year

Selection

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Specific product training


0 to 10 scale

Session 1: Vocabulary generated by consensus (> 70% mentions after discussions) on 3 contrasting products

Session 2: Tasting sheet with the definitions, evaluation protocol, scaled score (boundaries and intermediates) on the 3 contrasting products above

Session 3: Work on scale with 3 - 4 reference products. Initial score / correction / discussions

Session 4: Same test on the 3 - 4 reference products but individual scoring

Session 5: Same test followed by data processing (judge mean, repeatability, homogeneity of panel, etc.) 76


Specific product training

Approved / re-adjusted / re-trained

This specific training must be conducted before the start of every test / campaign

Testing

Number of repetitions to be defined

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Useful references

• Normes ISO :AFNOR (2007). Analyse sensorielle 7ème édition. La Plaine

Saint Denis, AFNOR.

• Livre généralisteSSHA and F. Depledt (2009). Evaluation sensorielle

Manuel méthodologique 3ème édition. Paris, Lavoisier

• Guide des bonnes pratiquesACTIA (1999). Evaluation sensorielle Guide de bonnes

pratiques, ACTIA (Association de coordination technique pour l'industrie agro-alimentaire).

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© D. Dufour

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Institution: Cirad – UMR QualiSud

Address: C/O Cathy Méjean, TA-B95/15 - 73 rue Jean-François Breton - 34398 MONTPELLIER Cedex 5 - France

Contact Tel: +33 4 67 61 44 31

Contact Email: [email protected]

Documents

WP2 Sensory Analysis Presentation