Sensory evaluation is the scientific analysis of food and other products using human senses. It is used to measure, analyze, and interpret reactions to characteristics like appearance, smell, taste, feel and sound. There are subjective methods that rely on human opinions and objective methods that use instruments for physical and chemical analysis. Some common subjective tests include difference tests to identify sensory differences, rating tests to quantify characteristics, and descriptive tests to characterize attributes. Objective tests use instruments to measure physical qualities like texture, color, and viscosity. Sensory evaluation is important for new product development, quality control and determining consumer acceptance.

1. SENSORY EVALUATION
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2. SENSORY EVALUATION
When the quality of a food product is assessed by means of human sensory
organs , the evaluation is said to be sensory or subjective or organoleptic. Every
time food is eaten a judgement is made.
Definition:
USA defined Sensory Evaluation as a scientific
discipline used to evoke measures , analyse and interpret
reactions to those characteristic of food and materials as
they are perceived by senses of sight , smell , taste ,
touch and hearing.
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3. WHY SENSORY EVALUATION USED
 It reduces uncertainty and risks in decision making.
 It ensures a cost efficient delivery of new products with
high consumer acceptability.
 Human observes are good measuring instruments.
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4. QUALITY EVALUATION
Quality is the ultimate criterion of the desirability of any food
products. Food quality can be evaluated by subjective and objective
methods.
subjective methods objective methods
 Appearance 1 Physical methods
Texturometer
 Taste Colorimeter
 Texture Tenderometer
 Colour Succulometer
Viscometer
Consistometer
Electric nose
2 Chemical method
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5. SUBJECTIVE METHOD
These methods of quality evaluation are based on
the opinion of the investigators. These are the individual
experience and preference. They are subjective because the
individual is required to give his opinion. The sensory organs
are appearance , taste, texture flavour.
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6. APPEARANCE
 Surface characteristic of food products contribute to the appearance.
 Interior appearance can also be evaluated. Lumps in a pudding or gravy
are not desirable can be judged by the eye.
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7. TASTE
 Taste sensation which the taste buds register are
categorised as sweet, salt , sour or bitter.
 Taste buds near the tip of the tongue are more sensitive
to sweet and salt.
 Those on the sides sour and those near the back
to bitter.
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8. TEXTURE
 Texture in ice cream depends upon the size of the
crystals.
 Coarse texture crystalline products are said to be grainy.
 The brittleness of food is another aspect of texture.
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9. COLOUR
 Ripeness of fruits like banana, mango, guava, papaya and
plum can be assed by the colour.
 Colour is used as an index to the quality of a number of
foods.
 The strength of coffee and tea is judged in part by the
colour of the beverages.
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10. OBJECTIVE METHODS
Methods of evaluating food quality that depends on some
measure other than the human senses are often called objective methods
of evaluation.
1. PHYSICAL METHODS OF MEASUREMENTS
This methods uses the different equipments for assessing
the physical attributes of the food products.
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11. COLORIMETER
 Helps to measure the intensity of the color of the food
product.
 Used in juices to measure the clarity.
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12. TEXTUROMETER
 Measures the texture of the
food products
 Measures smoothness , stickiness,
crunchiness, softness, juiciness,
handful, mouthfeel etc.
 It measures the amount of
food tensile strength.
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13. TENDEROMETER
 This applies compression , shear
to measure the tenderness.
 It is used to measure the tenderness
of animal products like meat.
 Various small teeth like structure
are present which is pressed into
the distance it move inside tells about
the tenderness.
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14. SUCCULOMETER
 Compression to squeeze
juice out of food as a
measure of succulence.
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15. VISCOMETER
 It measures the time required
for the food product to run
through a small hole of known
diameter.
 The term viscosity is used for
the product such as ketchup,
honey or sugar syrup etc.
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16. CONSISTOMETER
 This device also measures the
time required for the food to move
through the hole of known diameter.
 Consistometer is used for products
such as porridge , malt etc.
 Measures the thickness or the
thinness of the product.
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17. ELECTRIC NOSE
 It used to assess the type of
aroma present in the food.
 Chances of errors is very
negligible as the human
subjects are not present.
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18. 2. CHEMICAL METHODS OF MEASUREMENTS
 Chemicals are estimated in food spoiling like peroxide in
fats.
 Adulteration in foods e . g,, presence of starch in milk ,
metanil yellow in turmeric powder and loss of nutrients
during cooking can be estimated.
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19. SUBJECTIVE METHOD OBJECTIVE METHOD
Uses individual Uses equipment
Involves humans sensory organs Uses physical, chemical techniques
Results may be variable Results are repeatable
Determines human sensitivity Need to find technic applicable for food
Determines consumers acceptance Cannot determine consumer acceptance
Time consuming and expensive Essential for routine quality control
Essential for food development
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20. EVALUATION CARD
 The questionnaire or score card should be prepared carefully for each
test.
 The card should be clearly typed or printed.
 It should be simple and use unambiguous terms and directions in the
desired sequence of action as a guide to the evaluation.
 A score card may be as simple as indicating which sample is different
as done when duo trio or triangle testing is the mode being used.
 No single score card fits all experiment. Instead , the score card
needs to be developed for the specific experiment.
 All score cards should contain the date and name of the judge.
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21. DIFFERENT TYPES OF TESTS
Different sensory tests are employed for food
evaluation. The tests are grouped into four types.
1. Difference test
2. Rating test
3. Sensitivity test
4. Descriptive test
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22. DIFFERENCE TEST
A 1. Paired comparison test
 The panel members receive several pairs of samples .
These may be different or the same samples in each pair.
Samples are always given in code number.
 Different samples are given in each pair which differ in
the intensity of one characteristic e,g.. sweetness,
bitterness or rancidity. In each pair, the sample with more
or less intense taste will have to be picked out.
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23.  Sample card:
 Name:
 Date:
 Product
 You are given one or several pairs of sample. Evaluate the two samples in the
pair for--------
 Is there any difference between two samples in the pair?
 Code no. of pairs Yes No
--------- ---------- -----------
--------- ---------- -----------
--------- ---------- -----------
Signature
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24. A2 . Duo trio test
 This test employs three samples , two identical and one different.
 The panel is first given one of the pair of identical samples as known
reference sample R and then the other two successively in random order
and asked to much one of these with the first.
 A positive answer is required even if it is a guess. The chance of the
samples of placing the samples in a certain order is one half.
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25.  Sample card:
 Name:
 Date
 Product:
 The first sample ‘R’ given is the reference sample.
 Taste it carefully.
 From the pair of coded sample next given, judge which sample is the same as
‘R’.
 Set no. Code no. of pairs Same as R
 1 ---------- ----------
 2 ---------- ----------
 3 ---------- ----------
 4 ---------- ----------
 Signature
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26. A3. Triangle test
 This test employs three samples , two identical and one different ,
presented simultaneously to the panel.
 The judge asked to determine which of the three is the odd sample.
 A positive answer required even if it is guess. Since all samples are
unknown , the chance probability of placing the sample in a certain
order in one third.
 Two samples A & B can be presented in two combinations AAB & BBA &
for replication in six different arrangements AAB , ABA, BAA, BAB, ABB &
BBA.
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27.  Sample card:
 Name
 Date
 Product
 Two of the three samples are identical
.Determine the odd sample.
Set no. code no . of samples code no. odd of samples comment
1 ---------- ---------- ----------
2 ---------- ---------- ----------
Signature
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28. B. RATING TEST
These test given more quantitative data than difference tests
and can be used for the analysis of more than two samples at the same
time.
B1. Ranking test
This test is used to determine how several samples differ on the
basis of a single characteristic. A control need not be identified.
Panellists are presented all samples simultaneously with code numbers
and are asked to rank all samples according to the intensity of the
specified characteristic . In consumer analysis , the panellist are asked to
rank the coded samples according to their preference.
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29.  Sample card
 Name
 Date
 Product
 Please rank the samples in numerical order according to your preference or
intensity of aroma or taste characteristic of the product
 Intensity/Preference Sample code
 1 ----------
 2 ----------
 3 ----------
 4 ----------
 Comments(Type of off-flavour . etc. )
 Signature:
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30. B 2 . Single sample test
 This test is useful for testing foods that have an after
taste or flavour carry over which precludes testing a
second sample at the same session.
 The panellist is asked to indicate the presence or absence
and /or intensity of a particular quality characteristic.
With trained panellist, the completed analyses of two or
more samples evaluated at different times can be
compared .
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31.  Sample card
 Name
 Date
 Product
 Please taste and rank the sample carefully. Can you detect any off flavour in the
product?
 Circle one
 Yes No
 If you detect any off-flavour please describe it below.
 Intensity(Circle one) Comments
 Trace Off-Flavour is due to
 Moderate Off-odour
 Strong Off-taste
Residual taste
Other defects
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32. B3. Two sample difference test
 This test is a variation of the paired comparison test and measures the
amount of different.
 Each taster is served four pairs of samples . Each pair consists of an
identified reference and coded test samples . In two pairs , the test
sample is a duplicate of the reference sample. In the other two pairs ,
the test sample is the test variables.
 The panellist is asked to judge each pair independently as to the
degree of difference between the test sample and standard on a scale
of ‘0’ representing no difference to 3 representing extreme difference.
 Additional questions on directions on difference can also be asked . The
panellist is not to guess and he is panellist for guessing through the
coded duplicate standard in two pairs.
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33.  Sample card
 Name
 Date
 Product
1. Compare the coded sample to the reference sample independently in each of the four
pairs given. Test sample may or may not be different from the reference sample.
2. Determine the degree and direction of difference on the following scale.
 Degree Direction
 No difference 0 Superior to standard S
 Very slight difference 1 Equal to standard E
 Moderate difference 2 Inferior to standard I
 Large difference 3
3. Comment on what the difference is based on odour taste or both .
 Sample code no. Degree of difference Direction Comment
---------- ----------- ---------- ------
Signature
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34. B4. Multiple sample test
 In this test more than one test variable can be evaluated per
session but with reduced reliability.
 Each panellist is served 3 to6 samples depending upon the
number of test variables. One sample is a known standard .
The panellist compares each coded sample with the known
standard . One coded sample is a duplicate of the standard.
 Whatever score the panellist assign to the blind standard is
subtracted from the score he assign to the test variables. The
panellist is not to guess. Direction and degree of difference is
also to be judged.
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35.  Sample card
 Name
 Date
 Product
 You are given a standard or reference sample marked ”R”. Taste it carefully for the quality
characters to be evaluated. You are next given a no. of samples which are to be compared to
the reference sample for odour and flavour. Rate in each sample degree pf difference and the
direction of quality according to the following scale.
 Degree of difference Direction of quality
 Rating Difference from standard
0 None E-Equal
1 slight I-inferior
2 Moderate S-Superior
3 large
Sample code no. Odour Flavour
Degree direction comments Degree direction comments
Signature
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36. B5. Hedonic rating test
 Hedonic rating relates to pleasurable or unpleasurable
experiences.
 The hedonic rating test is used to measure the consumer
acceptability of food products.
 Ask each taster to taste each sample in turn and tick a
box from like extremely to dislike extremely.
 The results are analysed for preference with data from
large untrained panel.
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37.  Sample card
 Name
 Date
 Product
 Taste these samples and check how much you like or dislike each one. Use the appropriate scale to show
your attitude by checking at the point that best describes your feelings about the sample. Please give a
reason for this attitude.
code code code
 Like extremely
 Like very much
 Like moderately
 Like slight
 Neither like nor dislike
 Dislike slightly
 Dislike moderately
 Dislike very much
 Dislike extremely
Reason
Signature
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38. B6. Numerical scoring test
 One or more samples are presented to each
panellist in random order or according to a
statistical design.
 The panellist evaluate each sample on a specific
scale for a particular characteristic indicating the
rating of the sample.
 The panellist are trained to follow the sensory
characteristic corresponding to the agreed quality
description and scores.
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39.  Sample card
 Name
 Date
 Product
 Please rate these samples according to the following descriptions
 Score Quality description
 90 Excellent
 80 Good
 70 Fair
 60 Poor
 Sample score Comment
 Signature
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40. B7. Composite scoring test
 The rating scale is defined so that specific
characteristic of a product are rated separately.
 This method is helpful in grading products and
comparison of quality attributes by indicating
which characteristic is at fault in a poor product.
 It gives more information than the straight
numerical method.
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41.  Sample card
 Name
 Date
 Product
 Quality Possible score Sample score
 Colour 20
 Consistency 20
 Flavour 4
 Absence of defects 20
 Total score 10
 Signature
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42. C SENSITIVITY TEST
C1 . Sensitivity threshold test
Threshold test is defined as a statistically determined point on
the stimulus scale at which a transition in a series of sensation or
judgements occur.
There are mainly three types of threshold
a. Stimulus detection threshold is that magnitude of stimulus at which a
transition occurs from no sensation to sensation.
b. Recognition identification threshold is the minimum concentration at
which a stimulus is correctly identified.
c . Terminal saturation threshold is the magnitude of a stimulus above
which there is no increase in the perceived intensity of the stimulus.
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43. C2 . Dilution test
 Dilution tests are designated to establish the smallest
amount of an unknown material , developed as a
substitute for a standard product.
 The quality of the test material is represented by the
dilution number.
 The bigger the dilution number the better is the quality of
the test material.
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44. D. DESCRIPTIVE FLAVOUR PROFILE
METHOD
This is both qualitative and quantitative description for analysis in
products containing different tastes and odour .
For tomato ketchup the flavour profile analysis is given
Aroma Taste Mouth feel Texture
Garlic 1 Sour(Tea) 1 Chillies(1) Smoothness(
3)
Pepper 2 Sweet(S) 2
Onion 3 Salt 1
Cinnamon 2
Cloves 1
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45. Limitations of sensory evaluation
1. The result may be highly variable.
2. People with colors or other health problems temporarily lose
their maximum effectiveness.
3. Emotional burdens may influence an individual’s ability.
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46. REFERENCE
FOOD SCIENCE B. SRILAKSHMI
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