Lesson Sensory

Subject Sensory Evaluation Handouts 1Professor Jeffrey M Ostonal MAIEStudent BS Food Technology Third Year

SENSORY EVALUATION AN INTRODUCTION

LESSON 1 INTRODUCTIONa Historyb Definitionc Importance and Application

INTRODUCTION Simple concept of sensory tests has been utilized even at earliest period of mans existence Man relied on his senses and experience in the selection of commodities he needs (Select the

safe from the harmful) With passage of time manrsquos desires and levels of selectivity increased in degrees of

sophistication Choice was no longer only for survival but also for satisfaction Thus productrsquos lifetime in the market could be measured by the degree of satisfaction it

provides its consumers who invariably put a lot of weight on their preferences through their senses

Therefore a need to identify the factors associated with the commodity that could provide information on manrsquos basis for selection

And this would involve sensory characteristics which man identify with the use of his senses

A HISTORY Centuries ago man used his senses for acceptance or rejection of commodities With the growth of population and increasing demand for natural and manufactured products

the desire to understand characteristics of acceptable commodities became urgent 13th century studies on chemical components of food affecting its acceptability were started 1937 researches on flavours gained momentum Followed by an increasing number of works on quantitative measurements of food flavours

food characteristics and their acceptance Late 30rsquos development of sophisticated analytical techniques like gas- chromatography and

mass spectrometry World War II interest in food acceptance studies was further intensified when hungry soldiers

rejected their highly nutritious rations for lack of flavour 1945- 1962 the quartermaster Food and Container Institute for the Armed forces in Chicago

laboratories did a number of pioneering research on consumer acceptance of food flavours singly or in meal combinations

Early as the late 1800rsquos a review of the many publications about varied product attributes their nature interrelationships and correlations with acceptance and use by consumers reveals that much work on sensory evaluation has been generated and progressed on quickly through years

B SENSORY EVALUATION Definition

- A scientific discipline used to evoke measure analyse and interpret reactions to those characteristics of foods and materials as they are perceived by the senses of sight smell taste touch and hearing (IFT)

Sensory evaluation was one of the earliest methods of quality control and it is still widely used in industry However the level of application depends on the situation (eg beer and wine tasting to operators sampling of products from line)

Sensory evaluation terminologybull Sensory evaluationbull Sensory Analysisbull Organoleptic Analysisbull Taste Testingbull Psychophysicsbull Subjective Evaluation

Four variables affect sensory evaluationbull The Foodbull The Peoplebull The Testing Environmentbull Methods

Advantagesbull Gives real answer regarding consumer qualitybull Relatively cheap process (depending on how it is done)bull Rapidbull Many applicationsbull Objective methods are more reliable accurate and reproducible However they must be correlated to sensory evaluation to indicate a consumer response

Disadvantagesbull It is time consuming and expensive to carry outbull Tests are not objectivebull It cannot be used on materials that contain poisons or toxins bull It cannot be used to provide information about the safety composition or

nutritional value of a food

C IMPORTANCE AND USES OF SENSORY EVALUATION Since the concept is concerned greatly with the human reactions then logically the major

reason for the development of sensory approaches is to be able to determine product properties and utilize this knowledge to gauge the userrsquos reaction

Used by people whose interest is to determine characteristics of materials (food or non food) which cannot be measure by chemical or physical means

Where products are concerned the people responsible for their manufacture will find great involvement during different stages of production Among them would be those engaged in research and product development quality control production and marketing and sales

Indirectly involved would be students researches and scientists engaged in basic studies pertaining to commodity characterization whether sensorially chemically or physicallyThe Role of Sensory Evaluation Relative to Activities in the Manufacture of a Product (Fig 11)

Sensory Evaluation in Research Sensory Evaluation in Quality Control Sensory Evaluation in Production Sensory Evaluation in Sales and Marketing

The inner ring is the quality control circle The outer ring shows the relationship of between the four potential users of sensory

evaluation approaches The idea is that any product worth developing as observed by the Sales and

Marketing (I) must first be characterized physically chemically and sensorially resulting in a product profile (a)

Next would be the identification of properties which would most likely cater to consumersrsquo demands

Once identified test procedures (b) could be developed such that chemical and physical properties may be correlated with the sensory properties identified through the product profile (a)

There must be constant checking and validation of test procedures (c) while adequate recording and reporting (d) of all observed data must be carefully and religiously practiced

Should trouble arise (e) the recorded information could easily be tapped to resolve the problem before the product is again released for the end- users or consumers

The arrows go two ways because consumer complaints could be a starting point for restudying product characteristics identifying trouble point areas (e) retracing reports and record (d) checking physico-chemical test (campb) correlating with sensory tests (a) and eventually resolving the problem resulting in a go- signal for product release to consumers

Note All stages from (a) to (e) somehow involve sensory tests

Fig 11 further shows the need for constant coordination between Marketing and Sales (I) Research and Product Development (II) Quality Control (III) and Production (IV)

Sensory evaluation activity shown at the center of the two concentric circles is the point from which radiating arrows emanate linking itself to the rest of the inner circle components

The inner circle in turn is linked to the outer circle through consumer reactions gauged by Marketing and Sales (I)From this activities (a) to (e) start each having certain links and cross- links with Research and Product Development (II) Quality Control (III) and Production (IV)

Sensory Evaluation in Research Research activities in the industries are those which provide immediate answers to

problems connected with products manufactured Research activities and sensory evaluation as they relate to academic and research

institutions is shown in (Fig 12) They may involve the ff

Product Improvement Product Development Product Evaluation and Basic Studies

Product Improvement This could be done through removal of certain components which may cause

undesirable effects on the product or in some cases could be considered harmful to the consumers (eg removal of food coloring removal of MSG etc)

Other ingredient changes for product improvement could include substitution and addition or combination of the two(eg substitution of sugar by aspartame addition of xantham gum)

Product improvement may further take on the form of process change (eg removal of pulping step)

The degrre of change in a product is determined by the use of the following logical testing sequence

Difference tests to determine wether the experimental product is different from the control (if it is not different it cannot be better)

Affective tests if produces differ to establish wether the experimental product is liked more than the control (ie represents an improvement)

Product Development In the process of either improving or evaluating the product certain new ideas may

arise to catalyze the birth of a new item Such ideas may also originate from marketing and sales personnel who are in direct

contact with consumers Sensory evaluation of a new product may involve the following test sequence

Characterization of product prototype samples to determine uniqueness or a ldquopoint of differentiationrdquo from related established products

Evaluation of the experimental prototype sample to establish wether difference exists among them (or between prototype samples and a standard)

Determination of wether the prototype sample meets the acceptability requirements established for the products (eg wether they are equal to or better than the standard)

Product Evaluation Should remain as a regular research activity of any progressive industry Attention to product characteristics and their relationship to similar competitive items in

the market should be the concern of industries at all time Preference test between company and competitive products should be regularly

conducted for assurance of a place in the market or to check for a possible shift in consumer acceptance

Product evaluation may also include development of objective test procedures on the basis of sensory data It is of great importance especially to the food industry to be able to translate sensory information into those measurable by instruments

Basic Studies This is also called as ldquofundamental researchrdquo or ldquopure researchrdquo It seeks to discover basic truths or principles Results of basic research in theoretical knowledge have no immediate usefulness or

value to man Very often the academic and research institutions are relied upon for research

activities requiring solutions to basic problems Such undertaking if related to sensory evaluation may include

Panel selection and training Characterization of panel sensations Development of descriptive terminologies Sensory evaluation techniques and Physico- chemical tests which help characterize sensory qualities of

commodities

Sensory Evaluation in Quality Control Quality control can simply be defined as the maintenance of specified finished product

characteristics every time is manufacture This implies efficient control of raw materials and of the production process

Fig 13 clearly emphasizes the extent of use of sensory evaluation in the quality control functions of an industrial firm Among these major activities are

Product Matching (I) Grading and Standardization (II) Development of Test Procedures (III) and Trouble Shooting (IV)

Product Matching Would involve inspection and checks on incoming raw material (a) finished products

(b) and quality changes during storage (c) Efficient use of sensory evaluation may provide adequate check on the probable shift

in product quality Regular evaluation of product characteristic can be used to observe a decline in

product quality relative to consumer acceptability level

Grading and Standardization When specifications for size weight color defects etc are given the resultant list of

requirements eventually leads to a classification oftentimes referred to as ldquogradesrdquo Grading refers to the activity of sampling and examining raw materials (a) relative to

some set of specifications (specific quality characteristics) Acceptance or rejection would then be based on a set of specifications which at times

may become a company standard Correlations (e) between sensory and instrumental measures have to be established in

the making of grades and standards

Test Procedures

Test procedures have to be developed in order to measure qualities This requires close coordination with research and development (g) production (h) and

marketing (i) Product matching grading and standardization require test procedure which has been

found valid and reliable

Trouble Shooting This function could be necessitated by consumer complaints from the marketing group This could also arise from problems of production or from quality control charts and

records (j) showing significant shifts in product quality Sensory evaluation take active part in trouble- shooting problems requiring immediate

action since maintenance of quality is the major concern of of the quality control department

Sensory Evaluation in Production In production sensory evaluation is used for routine checks at 3 crucial stages

Raw material checks- use sensory evaluation data base to establish correlation with instrumental measures

In- process checks- standards and limits are assigned at various stages and plant people can be trained to taste products and make judgements on line

Finished product checks- trained panelists compare production samples to a reference

Sensory Evaluation in Marketing

Sensory evaluation in marketing plays a role in the following areas of activity Development of product vocabulary- This is concerned with the

development of product profile and attributes It serves as an opportunity to link the language developed from sensory work to that used by consumers A better vocabulary linkage will aide in the design of consumer questionnaires

Development and maintenance of sensory data bases- this deals with setting- up of reference standards With sensory data base the performance of a current product can be evaluated However the data base should include only data for successful established products It should not include data for products tested early in the developmental stages or products that were developed and later failed in the marketplace unless the failure was for non- product-related reason


THE HUMAN SENSES IN SENSORY EVALUATION

LESSON 2 THE HUMAN SENSES IN SENSORY EVALUATION

1 The Senses- An Introductiona The Sense of Sightb The Sense of Smellc The Sense of Tasted The Sense of Hearinge The Sense of Touch

2 Sensory Interactionsrsquo

1 THE SENSES- AN INTRODUCTION A consumer selects a commodity on the basis of his preconceived notion of its

acceptable attributes and his general idea of its fitness for use Selection is based largely on sensory qualities possessed by a given commodity The sensory properties of foods are related to three major attributes

bull Appearance - colour size shapebull Kinesthetics (texture)- mouth feel viscosity and hearing andbull Flavour - odour taste

These attributes are expressed as a continuum and not as finite properties (Fig 1) It is impossible to rate each one individually unless special precautions are taken eg blindfolds nose clipscoloured lights purees

the sensory properties of foods are perceived through the senses ofbull Sightbull Smellbull Tastebull Touch andbull Hearing

Stimuli A stimulus is any chemical or physical activator that causes a response in a receptor

eg eye is receptor for light ear is receptor for sound An effective stimulus produces a sensation the dimensions of which are

bull Intensitystrengthbull Extentseparationbull Durationretention andbull Hedonicslike-dislike

Receptors Receptors are the stimuli detecting cells of the sense organ eg taste buds on tongue

light receptors in retina of eye

Perception Perception is the psychological interpretation of sensations determined by comparison

with past experiences eg the sour taste of lemons is the perception of the sensation received by the receptors (taste buds) from a chemical stimulus (citric acid)

A SENSE OF SIGHT

The appearance of food

Stimuli = visible lightReceptor= retina of the eyePerception=sight vision appearance

The appearance of foods is a major factor governing its acceptability and can be subdivided into three main categories

bull Optical properties- colour gloss and translucencybull Physical form-shape and sizebull Mode of presentation-lighting packaging etc

Optical properties

Vision Vision is a complex phenomena consisting of several basic components A stimulus light from an external source interacts with the object and is brought to focus

on the retina of the eye The retina is the receptor of vision and contains two types of cells The rods are

responsible for vision in dim light and the cones are responsible for colour vision Light incident on these cells causes a photochemical reaction that generates an electrical

impulse which is transmitted to the brain via the optic nerve

FYI Colour blindness is caused by loss or lack of colour receptor cells in the cones Approximately 8 of the population have some defect with relation to colour mostly males

Light Visible light is that part of the electromagnetic spectrum which radiates between

wavelengths of 380 - 770 nm Different wavelengths produce different colours

380 - 450 nm =violet450 - 475 nm =blue500 - 575 nm =green575 mdash 590 nm =yellow590 mdash 770 nm = red

[NOTE All electromagnetic radiations are physically the same However the optical system of the eye is such that only the visible range of wavelengths is absorbed by the lens]

Light sources

Incandescent lights consist of a tungsten filament which is heated in an inert gas The higher the temperature the lighter produced Light from this source tends to be harsh and tends to highlight the red end of the spectrum

Fluorescent lights operate by electrical excitation of atoms that produces spectral lines at specific wavelengths which then impinge onto fluorescent materials which convert the incident light into light at a longer wavelength Light produced is softer but can produce colour distortion at particular wavelengths

Natural light is too variable for use in evaluating appearance of foods

Light - Object interactions Light incident on an object may be

bull Absorbedbull Reflectedbull Transmitted andbull Refracted

The relationship between and within each of these components is responsible for the colour and gloss characteristics of the food The main lightobject interactions produced are lightness hue chroma and gloss

Color Is a phenomenon which involves both physical and physocological components It is define as the evaluation of radiant energy (physics) in terms that correlate with

visual perception (psychology)Judd (1961) It can be describe in terms of hue value or lightness and chroma or saturation

bull Lightnessvalueintensity- corresponds to the overall relation of reflection to absorption which in essence also pertains to lightness or darkness of a given hue or color

bull Colourhue- Dominant wavelength and this could either be red yellow green or their combinations

bull Chromapuritysaturation- relates the amount of reflection of light at a given Wavelength It is associated with the degree of difference from the neutral gray of the same lightness or value

Physical form The second class of product appearance is physical form that can be subdivided into

three parts Shape Surface texture and Visual consistency

Shape and size are important from a food technologists point of view because these can be altered during the manufacture of processed products Some examples include

bull Sliced diced pieces wholebull Length of frozen French friesbull Cut of beansbull Extrusions

Surface texture can indicate product texture Some examples includebull Open dry structure of meatbull Wrinkling of peasbull Wilting of lettuce

Visual consistency can indicate product viscosity as inbull Setting of a jellybull Syrups of different concentrationsbull Pastes and purees

Mode of presentation

This aspect should be considered from a marketing point of view and is important because it influences sales

Mode of presentation is applicable on the supermarket shelf (at retail level) and also in terms of presentation at the table (home and restaurant)

Factors to be considered arebull Product description - name price ingredient etcbull Packaging - shape design colourbull Contrast - phenomena of adjacent colours andbull Illumination - affects apparent product colour carried

Defect as an appearance factor The presence or absence of some essential elements from a commodity may cause it

to be classified as defective which the extent of such significantly affects consumer reaction to the product

Most defects are visually observable and as such they would become a major basis for a consumerrsquos rejection of a product on the shelf

Note Appearance is an important aspect of food quality as it is the first subjective evaluation made of food quality The product has to pass the visual assessment before the consumer can or will consider the other parameters such as taste and texture

B THE SENSE OF SMELL

(Odourolfaction)Stimuli = volatile chemicalsReceptors= olfactory cells in the nosePerception=smell odour aroma flavour

Smell is one of our most primate senses Supposedly prehistoric people were moreinfluenced by smell than other senses

The human nose is capable of detecting thousands of different odour substances However our sensitivity is much less than other animals (Animals use smell - food mating territory etc)

Smell is detected both before and during eating Smell is an important aspect of flavour

Odour description requires the development of an odourflavour memory eg fishy flowery woody This is the basis of flavourodour memory development by wine judges and milkcheese graders Individuals vary a great deal in their sensitivity to different odoursaromas

From the diagram it can be seen that most of air misses the olfactory area Only 5-10 of inspired air passes over olfactory receptors

However this amount can be increased b sniffing harder obviously the more air which passes over the receptors the better the response

In order for odour to registerbull Substance needs to be volatile enough to get into air in the sensory

regionbull Substance needs to be partially soluble in mucus covering of

receptorsbull Minimum number of odorous molecules need to be presentbull Need to be in contact with receptors for minimum time

Olfactory intensity Human nose is about 10-100 times more sensitive to odours than any physico-

chemical analysis (eg gas chromatography) Odours vary considerably in strength

Olfactory threshold Detection threshold is the concentration where smell is detected Recognition threshold is the concentration where the smell is recognised

Olfactory interactions Nature of the response may change with concentration (eg perfumes at low

concentration are pleasant but at strong concentration may be unpleasant) Interaction of odours

bull Additive - increase intensitybull Suppressive - decrease intensity andbull Blending - when new odour unrelated to originals

Olfactory adaptation Initial sensation maybe strong - but weakens and makes identification difficult this is

due to adaptation of olfactory receptors In testing we therefore need to allow for this by

bull Taking first impression of odour andorbull Waiting between tests to allow receptors to recover

Note Smell is a major component of food flavour Human nose is much more sensitive than analytical instruments Foods contain numerous compounds of varying volatility that can

make analytical interpretation difficult (eg strong peaks may produce weak odour whereas weak peaks may produce a strong odour)

Smell measures perception of a mixture analytical testing does not

C THE SENSE OF TASTE

(Gustation)Stimuli = soluble chemicals or chemicals which are solublised during chewingReceptors= taste buds in mouthPerception=taste flavour

What is commonly referred to as tasteflavour is actually a combination ofbull Tastebull Smellbull Touch andbull Temperature

Strictly speaking taste involves only those sensations mediated by the Gustatory Nerve Fibres and these sensations have five (5) basic qualities

bull Saltbull Sweetbull Sour andbull Bitterbull Umami

Taste stimuli Taste response requires an aqueous solution of the substance (stimulus) to contact the

tastebuds Therefore saliva secretions are important in terms of ensuring contact between the

product and the taste buds Saliva production is generally stimulated by chewing as well as the appearance and

odour of the food The tongue is important as it brings the food into contact with the taste buds and also

provides a mixing action which enables an even distribution of food about the taste buds as well as preventing the development of concentration gradients

Taste receptors The receptors for taste are the taste buds and these are mounted on papillae (folds in

the skin of the tongue) The area of greatest response is the top of the tongue Other areas in the mouth and throat where taste buds are situated include palate

pharynx larynx tonsils epiglottis lips cheeks underside of tongue and floor of mouth

Taste buds are mainly located at the tip sides and rear of tongue There is very little response in the centre of the tongue Different areas of the tongue are most responsive to different sensations

bull Tip sweetbull Sides - saltybull Sides - sourbull Rear - bitter

Taste cells constantly degenerate and regenerate Their life cycle is 10 days and they are easily destroyed by heat

The tongue itself is important as it brings the food into contact with the taste buds and also provides a mixing action which enables an even distribution of food about the taste buds as well as preventing the development of concentration gradients

THE FIVE BASIC TASTES A basic taste is one for which specific taste buds have been identified as being

physiologically responsible for the particular taste sensation

Sourness This is the simplest taste as only acids (H+) produce sourness and as the (H+)

increases the sourness increases However there are some anomalies to this

bull organic acids are more acidic than expectedbull sourness of aliphatic organic acids relates to chain lengthbull some amino acids are sweet (aspartame)bull picric acid is bitterbull sugar may enhancedepress sournessbull sourness is also affected by pH and acidbull presence of buffers affects sourness

Sweetness The common substances that produce the sweet taste are the sugars and other

hydroxy compounds such as alcohols and glycols Other substances such as lead salts amino acids proteins non-nutritive sweeteners (cyclamates saccharin and aspartame ) also taste sweet

Saltiness Many crystalline water-soluble salts yield a salty taste but only sodium chloride gives a

pure salty taste Other substances taste salty but also bitter alkaline sweet and salt in various combinations

Bitterness Many chemically different compounds have a bitter taste However bitterness is mainly associated with alkaloids such as caffeine quinine

strychnine and nicotine Originally it was thought that bitterness was an indication of danger (poison) However

many alkaloids are used as drugs (eg codeine) and many other bitter substances are harmless (glycosides estersand aldehydes and tannins in wines and tea)

Bitterness is generally perceived at very low concentration and a relationship appears to exist between sweet and bitter as many sweet substances produce a bitter aftertaste (saccharin)

Bitterness is the taste which most people have difficulty in detecting and response level varies greatly from individual to individual

Umami Umami is the taste that has been shown to be associated with substances that contain

glutamate The most notable example is mono-sodium glutamate (MSG) MSG is well known as a flavour enhancer and can cause adverse reactions in some sensitive individuals

However there are many other compounds which contain glutamate and which are capable of producing the savoury spicy brothy taste associated with MSG Many foods contain naturally high levels of glutamate

Taste interactions Having described the 5 basic tastes it is obvious that foods are a very complex system

which contains many different taste compounds and therefore many different tastes The fact that there are only 5 basic tastes and yet we are able to detect hundreds of

different taste sensations is due to a series of complex taste interactions that can range from simple 2 way interactions to complex 5 way interactions

Interactions between the 4 basic tastes were previously described simplistically by the taste tetrahedron

Adaptation and fatigue During exposure to a stimulus sensitivity decreases due to adaptation and fatigue

This loss in sensitivity varies considerably with the taste (sweet sour salty or bitter) and also with the compound For example tasting a series of acids causes the sensitivity to be reduced by the preceding acids However recovery is usually rapid because most common organic acids are very soluble

Taste thresholds and sensitivity There is great variability between individuals in their levels of sensitivity Sensitivity is

affected bybull Temperaturebull Sleepbull Hungerbull Age andbull Sex

AbsoluteDetection threshold - Concentration of stimulus at which a subject can detect a difference between two samples in a paired test

Recognition threshold - Concentration at which the specific taste can be identified Recognition threshold is generally higher than detection threshold

Both absolute threshold and recognition threshold will vary between individuals Most people can detect taste within 02 - 06 seconds and therefore if there is no response within this time the level is sub-threshold However recognition times vary between the basic tastes

bull Salt = 03sbull Sweet = 04sbull Sour = 05sbull Bitter = 10sbull Vision = 002sbull Hearing = 001sbull Touch = 0005s

Reaction times also relate to retention times for example bitterness has the longest reaction time (10s) and the sensation lingers considerably after tasting

Summarybull Five types of taste receptors - salt sweet sour bitter and umamibull Different areas of the tongue respond to different sensationsbull Substances must be dissolved for taste buds to detect thembull Flavour of the food is a complex interaction of different tastes and

odours bull Sensitivity to taste varies between individuals and is affected by

their physiological state

D THE SENSE OF HEARING

(Audition)Stimuli = physical movement of sound waves in a medium (air)Receptor= ear drumPerception=sound hearing

Hearing Sound is the perception by humans of vibrations in a physical medium (air) The sound

of food when it is being eaten is an important aspect in determining qualityPositive aspects

bull Snap crackle and popbull Fizz of champagne or beerbull Crispiness of lettuce or celery andbull Tapping a melon for quality

Negative aspectsbullnoisy environment may distract tasters or mask product sounds

E THE SENSE OF TOUCH

(Texture Kinesthetics)Stimuli = physical contact between the food and body tissueReceptors= muscles and nerves in mouth and fingersPerception=touch feel texture viscosity

Texture usually relates to solid food while viscosity relates to homogeneous liquid foods and consistency relates to non-homogeneous liquid foods

Instrumental methods only measure one aspect of texture and again cannot relate the complex interactions which produce the perception of food texture

Finger feel FirmnessSoftness indicates the eating quality of some food products

bull Ripeness level of fruit such as avocado and mangobull Crumb texture of breadbull Firmness of cheese andbull Spreadability of butter or spread

Juiciness can be used as a subjective quality index (eg the ldquothumbnailrdquo test for corn)

Mouth feel

Liquids

Textural Terminology Mechanical Characteristics ExampleViscosity thin to viscous milk creamConsistency thin to thick fruit yoghurts

SolidsClassification of textural characteristics - assessed mainly by chewing

Textural Terminology Mechanical Characteristics ExampleHardness Soft firm hard fruit ripeness cheese maturityBrittleness Crumbly crunchy brittle muesli bars and

biscuitsChewiness Tender chewy tough meatGrittiness Gritty grainy coarse stone cells in fruit sand in ice-

creamFibrousness Fibrous cellular stringfibre in vegetablesMoistness Dry moist wet watery cracker biscuit cheeses water

melonOilinessGreasiness Oily greasy fatty french fries chips

2 SENSORY INTERACTION As can be noted that when eating or tasting food there is a continuous relationship

between the senses and unless steps are taken to separate the individual senses or stimuli interactions may occur

It is not known whether interactions occur at the receptor site or the brain However the second option would appear to be more likely

Interaction between senses This is the ability of a response from one modality to influence or affect the response

from another There are two aspects of this

Positive - interactions giving clues to possible identity eg pink milkshake being strawberry flavouredNegative - If clues are not correct this may lead to confusion and a

wrong judgement egpink milkshake with pineapple flavourTypes of sensory interactions

Taste - odour Receptors for these two senses are very close so that interactions between these senses are

highly likely and these may be important in classifying a particular tasteTaste - tactile

The taste threshold for sugar salt caffeine has all been shown to be lower in water than in tomato sauce This may be due to the fact that in more viscous solutions the chemicals do not react with the receptors as easily as in pure solutions

Taste - sight This is a very important aspect because vision is the first sense affected and appearance of a

product will have a major influence on absolute quality Bright colours indicate strong flavours whereas dull colours indicate mild flavours

Other interactions include

bull Odour - Sightbull Odour - Tactilebull Taste ndash Hearingbull Odour ndash Hearing

Multiple interactions Multiple interactions between more than two modalities are also possible Example Tasting food pureed blindfolded and with nose clips gives a different response

than when interactions are allowed

Interactions between stimuli These interactions are more difficult to define and measure but are just as important as

interactions between the senses Some examples includebull suppression of one flavour by another eg sweetness is suppressed by acidity This is the basis of ensuring brixacid ratio for fruit juices are constantbull neutralisation of one flavour by anotherbull blending to produce a totally different flavour eg garlic flavoured cheesesbull partial blending producing a new flavour and the original flavoursbull no effect original flavours are distinct and separate eg fruit in cheesebull intensification resulting in enhancement of flavours eg salt and MSG on food improves the natural flavours

Similar situations may exist for all other stimuli

Summary Interaction must be considered when designing sensory panels If only one sense or stimulus

is to be evaluated then all others must be masked However if interactions are required then ensure this can be achieved by means of sample preparation


OPERATIONAL PRINCIPLES OF SENSORY TESTING

LESSON 3 OPERATIONAL PRINCIPLES OF SENSORY TESTING

1 Requirements for Sensory Evaluationa Panellistsb Physical and environment requirementsc Designing the experimentd Sample preparation and serving

1 Requirements for Sensory Evaluation

When evaluating properties of foods using people as measuring instruments it is important to control the methods and conditions of testing as rigidly as possibly This helps to eliminate the numerous errors or biases that can be caused by psychological and physiological factors

The mental attitude and physical condition of a taster and the atmosphere of the testing environment all influence their judgements There are therefore a number of basic rules which should always be applied as stringently as circumstances allow when running taste panels

These relate tobull Selection of panellistsbull Preparing the testing environmentbull Designing the experimentbull Preparing and serving samples

General principles that should always be followed are Never ask anyone to taste food they do not like Make sure that the correct panellists are selected (see section on panel selection and

training) and that they know in advance when they will be required Keep a strict control over all variables except those being tested (eg sample size and

temperature) Make sure the environment gives optimum opportunity for concentration Tasting properly is

a difficult job Train panellists to be silent while tasting This prevents panellists from influencing one another

Make tasting interesting and desirable Use rewards to motivate taters vary these and choose foods that contrast with those being tasted Motivated tasters are more efficient Give feedback on results whenever possible Avoid giving any unnecessary information to panellists that may influence their scoresTasters usually find what they expect to find eg in a storage test they expect to find samples deteriorating

Plan your experiment in advance Which will be the best test to use Consider all aspects including how you will get the information required from your results (statistics) Run preliminary tests ie practise and choose the best method for

Sample size - adequate but not excessive Serving temperature - standardise for all samples It must be

maintainable and be an acceptable temperature for the food Serving vessels Eating utensils

Sample preparation and servingo Serve tasters promptly and make sure they have everything they needo Run a taste panel as you would expect a good restaurant to be run ie give

courteous friendly service be efficient and serve good foodo Keep accurate records of any cooking or preparation methods used Record

temperatures and size of samples served and any special conditions (eg coloured lighting)

o It is important that panellists do not see the samples being prepared as this may indicate quality difference

A The Panelist If a set of individuals are to function as tools for evaluating product characteristics they

must posses the ability to discriminate and the willingness to participate in evaluation activities

Types of Panelists Consumer panel

Consumer-type panel and Laboratory panel Expert Tester

Consumer Panel A large number of respondents selected through adequate sampling

techniques and used in consumer testing to measure product acceptability and preference

Respondents required for reliable result usually exceeds 100 Not given training nor are test to be replicated Large variability among responses is expected and this can be minimized only

by efficient sampling method and by increasing the number in the sample from identified consumer population

Consumer-type Panel

Emerged due to many considerations involving time money and effort For this type of panel the respondents are within the range of 40-100 The information expected to be elicited would be mainly preference or level of

product acceptability If properly sampled an adequate number of respondents could even serve as

a real consumer panel

Laboratory Panel Small Trained Panel In general the number of panellists most often used in evaluation is ten (10) A large number (20) would be desirable although the larger the sample size

the better would be the expected results a larger number (30) may become costly and at times unmanageable as a laboratory panel

In cases where a panellists are well-trained and consistent in performance a number as low as three or four can be utilized in replicated tests

Useful for discriminatory tests and identification of specific product attributes qualities or characteristics

Panel may even be equated to a tool that can measure qualities with considerable validity and precision(Subjective judge could be more objective)

The Expert Panel Is supposed to be so thoroughly knowledgeable about the product that his

judgement is well- respected and can be used for decision making There is no formal training or system of evaluation Although not recommended such types of testers are still being used in

products like wine tea coffee and tobacco

Qualification of Laboratory Panelists Types of responses

DifferenceRankScalingDescription

Major QualificationInterestHealthIntegrityAttitude

MotivationStability

Other QualificationsAbsence of BiasIntelligencePersonal Characteristics

Types of responses Discrimination tests could elicit varied types of responses These include

difference ranking scaling or scoring and identification of quality characteristics by the use of descriptive terms

All these responses expected from panellists can be elicited only if the latter are well chosen and duly trained

o Difference- Trained panels can be and o succeed in determining product differences on the basis of some specified qualityNeeded for product development and improvement storage studies and in quality control tests

o Rank- Normally employed in cases where relative differences of the product are to be determined These forces the panellist to rate samples in decreasing or increasing order depending on the specific attribute used as basis for judgement

o Scaling- scaling could be made for a selected product attribute which could have varying degrees of intensity The panellist would then be expected to indicate the intensity in the scale which corresponds to his own reaction to that particular attribute of the commodity

o Description- Closely allied to scaling is product characteristic identification through development of descriptive terms Trained panellists discuss among themselves and eventually agree on a specific term commonly understood by them to describe the product

Major Qualifications of Panelists The evaluators must possess certain qualifications which can more or less

equate them to an objective instrument in terms of performance The qualifications that will be described below are prerequisites for an effective

sensory evaluator Some of these traits are inherent in some persons while in others they have to be developed

o Interest- There is must need for assurance that a selected judge is willing to participate in the evaluation work Without interest a panellist cannot be useful

o Health- Persons suffering from illness that can affect sensitivity may not qualify as panellists

o Integrity- Judges are expected to respond exactly what they honestly think or feel about the product under test

o Attitude- It could be strongly related to development of interest and a healthy work attitude which are good starting points for an efficient evaluation

o Motivation- There is link between attitude and motivation It seems that the greater the motivation the better the chance for a positive attitude toward work at hand when there is less or no motivation at all Some of these include ldquotreatsrdquo or rewards recognition or praise understanding of the study and onersquos role in it and the sharing of result of the tests

o Stability- Stability implies precision in responses A judge with high sensitivity to certain sensory qualities will have the ability to observe slightest differences between samples Sensitivity oftentimes increases assurance of high validity and precision As such results could have sustained stability

Other Qualificationso Absence of Bias- Biases stem from a personrsquos background which

could include stereotype opinions and regional taboos and prejudices This is traceable to family beliefs customs and traditions

o Intelligence- Panelists should possess enough native intelligence to understand instructions However the more complex the evaluation requirement and the greater the amount of panel participation in the test situation the higher the level of intellectual and educational requirement

o Personal Characteristics- have some effects on sensitivity Such as Sex- literature reveals that sensitivity to stimuli in

general is not sex-linked Age- some claim that manrsquos sensitivity to most tastes

is greatest between age 20-50 years Personal habits- would most likely affect taste

sensation include smoking sleeping and eating Emotional stress fatigue lack of concentration anger

and other such sensations which affect onersquos work performance may also affect evaluation

Selection of Panelists- If a set of individuals are to function as tools for evaluating product characteristics they

must possess the ability to discriminate and the willingness to participate in evaluation activities

- Unlike consumer panel the selection process for a laboratory panel is of utmost importance if effectivity of judgement is to be obtained

- Selection process would have to be based on rigid procedures with due consideration to varied characteristics which could affect evaluation

Need for Selection Since laboratory panel is expected to become an analytical tool possessing

qualities of objectivity precision and reproducibility there is a need for proper selection processes

It is definitely less costly to run tests for differences using a small sensitive panel than a large consumer-type group

Steps in the Selection Process Before the application of the final process some sensitivity tests may be

conducted This activity could fulfil some objectives related to selection

a) It could show indications of levels of interest among potential panellists

b) It can be used as basis for determination of an individual consistency and ability to understand instructions

c) It should provide information of onersquos level of sensitivity to given substances and

d) Such an activity can serve as an introduction to sensory evaluation itself

The stages in the conduct of such tests are as followsFirst stage Some panellists are eliminated for lack of sensitivity to

the attribute tested or for possessing extremely high sensitivity relative to the rest of the evaluators

Second stage Remaining panellists are observed and would be given additional tests if they possess the ability to establish and use stable subjective criteria for judgement

Third stage A pool panellists showing potentials will be selected Here there is an utmost need to develop and sustain panel interest

After these stages the final selection process for judges of specific commodities can be initiated

Goals in the selection process could be identified as followsa) To determine the panelistrsquos discriminating abilityb) To measure his level of performance in tests for recognition of

flavours and odorsc) To find out his total performance relative to other panelists

andd) To know his personal qualities necessary for continuity and

efficiency of evaluation Based on these goals selection process involves the following steps

Step 1 Set up situations similar to actual testsa) Use physical environment expected to be utilized in actual

testb) Provide scoresheets similar to what would later be used in

product testsc) Set up test methods expected to be employed in actual

evaluationStep 2 Choose test methods which allow maximum discrimination

between panellists based on sensitivitya) Prepare tests which allow variations expected in actual

sampleb) Adjust difficulties such that the group as a whole will be able

to discriminate while some failStep 3 Determine desired group size

a) Start with as large a group as possible or feasible under a particular situation

b) Screen on the basis of relative achievement continue the screening efforts until desired size of top- calibre panellists is attained

c) At each step reject those who are obviously inadequate while still making certain that more panellists than the desired number are retained

Step 4 Obtain the general background information of selected panellists

a) Age sex marital statusb) General health conditionc) Smoking and eating habitsd) Type of food regularly consumed prejudicese) Interest and availabilityf) Other information pertinent to a personrsquos experience

sensitivity and willingness to participate

Once a set of panellists are selected the problem of sustain interest willingness and motivation to continuously perform at a more or less constant ability level will have to be ascertained

Training of Panelists- Potential panellists who undergo the selection process are introduced in effect to the

basic mechanisms of sensory evaluation But effectivity in the achievement of the goals for evaluation can be enhanced through further training

- Training is integral to the proper implementation of sensory evaluation techniques

Need for training For human subjects there are cumulative effects of added experiences on the

learning process and proficiency in test applications Expectedly the training process can result in considerable improvement in panellist performance with time

Training affords the panellist a greater opportunity to clearly understand the study and to know his cooperation and participation can contribute to its success

Guidelines for Training A training program for panellists can be set up using basic guidelines as

follows 1 Plan for a well- organized approach to evaluation

a) Set your schedule fro training programs and adhere to it as closely as possible

b) Plan for an efficient approach to product presentation considering its possible effects on reactions of panellists

c) Scoresheets intended to be utilized for the tests must be well- prepared and consistent with the goals which the planned evaluation is supposed to accomplish

d) Maintain a pleasant and congenial atmosphere for evaluation 2 Lay down proper conditions for learning and thorough understanding

of onersquos role as panellista) Prepare an effective approach to imparting knowledge about

purposes of requirements and procedures for evaluationb) Provide adequate opportunities for the panellist to understand

his role in the program and devise some system of awards and rewards for participation

c) There should be continuous and efficient evaluation of individual and group performance

d) Determine onersquos capabilities for evaluating results and making realistic analysis and interpretations

3 Identify and observe problem areas associated with product evaluation which may affect efficiency of training

a) Determine the requirements for product presentation and feasibility of utilizing them under present situation

b) Consider the possibility for the onset of taste fatigue particularly for the novices in taste evaluation

c) Review the requirements for adequate testing situations 4 Decide on the extent and frequency of panel training

After consideration of the set of guidelines the procedure for training actually follows the requirements in the conduct of a regular evaluation session

Methods Used to Select and Train Panelists in the Laboratoryo Sensitivity tests- to determine recognition of basic tasteso Difference tests- to determine ability to detect specific variations of

the test product and to generate reproducible resultso Descriptive tests- to determine ability to measure differences and to

generate reproducible results

Procedures for Organizing a Training programStep 1 Orientation or prospective panellists with regards to

a) Objectives of the program requiring sensory testsb) Role of the panellist in the programc) Explanation of the method to be utilizedd) Discussion of product attributes to be evaluated

Step 2 Practicea) Actual evaluation sessions using selected test methodb) Discussion of techniques to be utilized in the final evaluationc) Replication of tests in several sessions to test consistency

and performanceStep 3 Performance evaluation

a) Evaluation of panelistrsquos performance in the test relative to other trainees

b) Statistical approaches to analysis of collected data and system of recording and reporting of results

c) Analysis and interpretation of results to determine panelistrsquos performance improvement or deterioration with increase in number of training sessions


Physical and Environmental Requirements

B Testing Environment The main considerations to keep in mind when preparing an area for sensory testing

concern the requirements for an atmosphere conducive to concentration where conditions can be controlled

Sensory panellists need somewhere comfortable and free from distractions if they are to be able to tune in to the sensations triggered by the stimuli in the food products they taste

Product characteristics can be markedly affected by temperature and humidity and appearance is affected by lighting intensity

The conditions should be controlled in order to bull Reduce biasbull Improve accuracybull Improve sensitivitybull (compare to the conditions used in an analytical laboratory

International standard (ISO 8589-1988) The standard looks at the design of the testing area for both new and existing

buildings It also specifies which recommendations are considered essential and which are only desirable

Important points summarised from the standard are listed below If designing an area that is to be dedicated solely to taste panel work these should be seriously considered

Total area should includebull Testing area with individual booths and a group areabull Preparation areakitchenbull Officebull Cloakroombull Rest room andbull Toilets

General testing areabull Easily accessible but in quiet positionbull Location - close proximity to preparation area but separate entrance and

with complete close-off capabilitybull Temperature and relative humidity - constant controllable and

comfortable (Air conditioned booth 25oC and relative humidity of 40)bull Noise - keep to a minimum soundproof area as much as possiblebull Odours - keep area free from odours (air conditioner with carbon filters

slight positive pressure)bull Use odourless materials in construction and decorationbull Use odourless cleaning agentsbull Decoration - use neutral light colours for walls and furniture (eg off-

white light grey) Absence of hues will prevent unnecessary alteration of the commodityrsquos color or appearance Distraction would also be minimizedbull Lighting - ambient lighting must be uniform shadow-free and controllable

For consumer testing - as close to home conditions as possible

Booths Number - minimum three normally five to ten - six is a useful number since it fits in

well with balanced ordering of 3 samples (See sample booth layout Fig 3 amp 4)bull Space - allow sufficient space for movement of tasters and for serving samplesbull Set-up - permanent booths recommended Temporary acceptable If adjacent to preparation area include openings in the wall to pass samples through Size and style specified Consider space for samples utensils spittoons rinsing agents scoresheets and pens computerised equipment Include comfortable seatsbull Lighting - uniform shadow-free controllable adequate intensity for assessing appearance Devices to mask appearance (eg dimmers coloured lights or filters)

Group work area General Necessary for discussion and training purposes Include large table and

several chairs Lazy Susan useful Include board for discussion notes etc Lighting As for general area with coloured lighting options like booths

Fig 1 Floor Plan and layout for a taste panel areaFig 2 Floor plan for a small sensory evaluation area where portable panel booth is utilized

Fig3 Individually closed doors of uniformly designed sensory evaluation booth useful especially for odor testing

Fig4 Individual sensory panel booths slowing light source (a) red and (b) white with (c) opaque light diffuser

Preparation area General Located close to assessment areas but no access to tasters Design for

efficient work-flow Well ventilated Flexible services (ie plumbing gas electricity) Equipment Depending on testing required Include working surfaces sinks cooking

equipment refrigerator freezer dishwasher etc Storage space for crockery etc Crockery glassware etc for serving samples

Office area General Separate but close to testing area reasonable size desk filing cabinet

computer bookcase Photocopying service needed

Additional areas Useful to include rest room cloak room and toilets

Practical alternatives The requirements specified in the International Standard (ISO 8589) will obviously

provide a suitable area but they are not always feasible either from the point of view of financial resources or physical space available

Minimum of 2 areas Preparation area and office area If possible position these at opposite ends of the

room to avoid messy paperwork Testing area with entrance separate from preparation area

Preparation area requiresbull Adequate storage for utensils and equipmentbull Adequate working surfaces to set out samplesbull Washing up facilities - minimum double sink with hot and cold running waterbull Refrigerator - minimum 2 door with separate freezer preferably at least auto-defrostbull Cooking equipment - depending on sample requirementsbull Rubbish bin - large with liner bagsbull Source of boiling waterbull Hand washing facilities

Testing area requiresbull Comfortable chairs for panellistsbull Minimum space - 4 panellistsbull Table which can be easily divided into booths if requiredbull All equipment likely to be needed while a panellist is tasting eg pencils spittoons toothpicks tissuesserviettesbull Well placed efficient lightingbull Waiting are with noticeboard - for tasters to wait for booths to become free and to collect rewards after tasting

A system using collapsible booths can work quite well if it is not possible to keep an areasolely for sensory work These may be made of painted wood heavy duty cardboard orcorflute They can be made specifically to fit any available benches or tables and foldedand stored when not in use

The type of facility will depend onbull Finance bull Available space bull Frequency of use bull Tests conducted

Subject Sensory Evaluation Handouts 22

Professor Jeffrey M Ostonal MAIEStudent BS Food Technology Third Year

Sample Selection and Preparation

C Sample Selection and Preparation This is considered an integral part of the test method and is expected to be inherently attended

to when sensory test method has been selected because this could greatly affect information obtained on product attributes

Sample preparation should be uniformbull Temperaturebull Cookingbull Thawingbull Size and shape (provided this is not a variable)

Sample should be randomly allocated tobull Avoid biasbull Overcome any nonmdashuniformity

Sample size should be adequatebull 30g solidsbull 30mL liquids

Samples should be served immediately after preparation to reducebull Flavour lossbull Discolorationbull Textural changes

Sufficient samples should be prepared to allow for seconds

Containers for presentationContainers for presentation and tasting should bebull Cleanbull Identical for all samples and sessionsbull Disposable containers or remdashusablebull Coloured to mask product appearance (if required)bull Relevant to product

Serving temperaturebull Serve at room temperature where possiblebull Preference tests use normal temperaturebull Difference tests may alter temperature to accentuate flavoursodoursbull Do not overheat

1048707 too hot to taste1048707 drying out1048707 off flavours1048707 browning

Dilutions and Carriers Most foods should be served in the way they are normally eaten However some products

such as spices chillies alcohol onions etc may require dilution before testing If dilutions are used they must be uniform in terms of diluent and concentration

Carriers are substances that are added to assist tasting of certain products Carriers are a problem because they can be

bull Expensivebull Time consumingbull Variable qualitybull Difficult to control productcarriers ratio uniformity

For example developing a cake icing individually may not allow for interaction with flavour or it may be incompatible with the cake (affects texture or falls off)

Number of samples

Samples Sessions

The number of samples presented at any testing session will depend onbull Type of product - strong flavour mdashgt less samplesbull Type of testbull Rating scale may require fewer samplesbull Test dictates sample number eg triangle test = 3 samplesbull Type of panel mdash trained experienced -gt morebull Experimental design

As a general rule usually not more than 6 samplessessions

Sessions Trials

Before starting your scheduled tasting sessions run two preliminary sessions These will familiarise your panel with the scoresheet the products to be tested and the procedures you wish them to follow

It also gives you practice at preparing and serving the quantity of samples needed and a last chance to iron out any unforeseen problems In calculating the number of sessions consider the following

bull Total number of samples for tastingbull Statistical designbull Taster fatiguebull Motivationbull Type of panel (traineduntrained)

Sample Coding

Remove possible bias or influence from samples codes Do not usebull Single digit numbersbull Consecutive lettersbull Same codes at consecutive sessions

Randomly or statistically generated three digit number codes are best

Order of Presentation

Always use either a random order of presentation or a statistically balanced design to avoidbull Donkey vote (first is best last is worst)bull Position bias - in triangle tests middle one is different

bull Contrast effect mdash good after bad appears better or bad after good appears worse

Devise your own system for remembering orders eg 3 digit numbers - put in sequence of one of digits Keep it a secret

Always work systematically in coding labelling setting up eg as in reading a page(1) Left to Right(2) Top to Bottom

This provides an automatic check if something goes wrong

Balance presentation of samples whenever possible This avoids contrast effect

ie 2 samples A B - Half panel taste A first other half taste B first- Half panel receive A on the left other half receive B on the left

3 samples - 6 different orders in which they are tasted Use every order the same number of times Number of tasters is a multiple of six

- Position of samples on plate must also be balanced

4 samples - 24 different orders use them all if possible (see table below)

4 samples - Generate random order Write out set of cards and shuffle them

When you cannot use balance to eliminate bias use randomisation

Expectation Error Any information a panellist receives before a test will influence the results This is

called expectation error To overcome this

bull Do not give detailed information about treatmentsbull Do not use people on panel who know what the treatments arebull Sample coding and design can prevent expectation error

Logical Stimulus Error Tasters look for clues to get the ldquorightrdquo answer eg a difference in sweetness may be

associated with sample differences such as size shape and colour

This error can be overcome by ensuring sample preparation is uniform or use masking

Halo Effect When more than one factor in a sample is evaluated at one time the result obtained

may be different than if factors evaluated separately This can be overcome by tasting each aspect separately

However this is time consuming and would only be done if extremely accurate results were required Testing one aspect at a time in preference does not simulate the ldquoreal situationrdquo ie consumers do not taste every aspect separately

Suggestion Influence of other panellist may bias or influence results This can be prevented by

bull Using boothsbull Not allowing talking in tasting areabull Reducing outside distractions


Other Factors in Sensory Testing

D Other Factors in Sensory Testing

Physiological factors in taste testing

Time of Testsbull Monday and Friday are recognised as being bad days for tastingbull Normally taste 1 hour before meals and 1 - 2 hours afterbull Sometimes this becomes difficult in practice due to

bull Unavailability of tastersbull Number of sessions

Smoking Taste Affecting Substances As indicated earlier smoking affects sensitivity to flavours mdashtherefore should either

bull Not use smokersbull Ensure they do not smoke for at least 1 - 2 hours before tastingbull Chewing gum mints and spices etc may also influence taste

Illness Sensitivity of people suffering from illness is reduced -particularly those with colds or

flu (physical and psychological)

Likes Dislikes In preference testing a series of treatments within a specific product type it is

legitimate to eliminate people who dislike the product (or those who are not discriminatory)

Palate Clearing

It is a good idea to get panellists to cleanse their palatebull Before tasting to remove any lingering tastesbull Between samples to reduce adaptation of taste budsbull Warm water biscuits bread apples may be used as a palate cleaning agent

Palate clearing can be optional but whatever is done must be constant The time between samples should also be kept constant if possible

Perfumes Spices Ask panellists to refrain from wearing strong perfumes or breathing spicy odours

wherever possible

Psychological factors Because sensory evaluation is a subjective system it is necessary to allow for any

psychological factors that may influence results and possibly lead to errors

Motivation Good results can only be obtained from a co-operative responsive panel Tasting

becomes a chore when there are large numbers of samplessessions involved Motivating panellists by can reduce this problem bybull Stressing importance of workbull Stimulating company expansionbull Greater profitsbull More paybull Ensuring panellists know what is involved with the trial ie sessions

products when and where tasting will be conductedbull Having adequate facilitiesbull Using effective methods and designsbull Publicising results obtained from workbull Rewarding panellists

Questionnaire design Questionnaire design should be simple and easy to follow in terms of design and

language and make sure tasters know how to use it You may need to include some instructions on the scoresheet itself but it is usually better to give instructions verbally to your panel first The questionnaire should generally not be more than one page and include

bull Namebull Datebull Timebull Productbull Sample codesbull Instructionsbull Comments section

- A scientific discipline used to evoke measure analyse and interpret reactions to those characteristics of foods and materials as they are perceived by the senses of sight smell taste touch and hearing (IFT)

Sensory evaluation was one of the earliest methods of quality control and it is still widely used in industry However the level of application depends on the situation (eg beer and wine tasting to operators sampling of products from line)

Sensory evaluation terminologybull Sensory evaluationbull Sensory Analysisbull Organoleptic Analysisbull Taste Testingbull Psychophysicsbull Subjective Evaluation

Four variables affect sensory evaluationbull The Foodbull The Peoplebull The Testing Environmentbull Methods

Advantagesbull Gives real answer regarding consumer qualitybull Relatively cheap process (depending on how it is done)bull Rapidbull Many applicationsbull Objective methods are more reliable accurate and reproducible However they must be correlated to sensory evaluation to indicate a consumer response

Disadvantagesbull It is time consuming and expensive to carry outbull Tests are not objectivebull It cannot be used on materials that contain poisons or toxins bull It cannot be used to provide information about the safety composition or

nutritional value of a food

C IMPORTANCE AND USES OF SENSORY EVALUATION Since the concept is concerned greatly with the human reactions then logically the major

reason for the development of sensory approaches is to be able to determine product properties and utilize this knowledge to gauge the userrsquos reaction

Used by people whose interest is to determine characteristics of materials (food or non food) which cannot be measure by chemical or physical means

Where products are concerned the people responsible for their manufacture will find great involvement during different stages of production Among them would be those engaged in research and product development quality control production and marketing and sales

Indirectly involved would be students researches and scientists engaged in basic studies pertaining to commodity characterization whether sensorially chemically or physicallyThe Role of Sensory Evaluation Relative to Activities in the Manufacture of a Product (Fig 11)

Sensory Evaluation in Research Sensory Evaluation in Quality Control Sensory Evaluation in Production Sensory Evaluation in Sales and Marketing






































commodities














Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible














































commodities














Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible




































commodities














Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible






























commodities














Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible




























commodities














Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible






















Test Procedures
































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible








































A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible


























A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible



















A SENSE OF SIGHT





Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible












Optical properties










Light sources
















































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible
























































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible






































































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible

























































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible








































































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible



























































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible










































Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible


























Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible









Mouth feel

Liquids
























































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible













































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible
































Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible














Consumer-type Panel















MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible









MotivationStability






















































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible














































































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible
























































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible


































































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible











































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible

































































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible






















































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible









































Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible


























Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible












Number of samples

Samples Sessions



Sessions Trials




Sample Coding







































Palate Clearing




wherever possible











































Palate Clearing




wherever possible



























Palate Clearing




wherever possible
















Palate Clearing




wherever possible












Documents

Lesson Sensory