Two channels can be
adopted for screening and selection of sensory panel members. First, from the
quality control laboratory, and second source is from the processing unit.
Another option is to have a mixed source i.e. some of the members from quality
control laboratory and the remaining from processing sections. Normally double
the numbers of panelists finally required are selected. For example, if 7
members are needed in the final panel at least 15 should be initially screened
i.
Qualification for Screening a Panelist
Interest and motivation: Candidates
who are interested in sensory analysis and have investigating curiosity are
likely to be more motivated and will do better jobs.
Attitudes to foods: Candidates having
strong liking or disliking towards a dairy product should not be screened.
Knowledge and aptitude: The evaluators
should have capacity to concentrate and to remain unaffected by external
influences. He should have knowledge about basic aspects and principles of milk
and its processing into products.
Health: Candidates should be in good general health. They shall not
suffer from any disabilities, which may affect their senses, or from any
allergies or illness and shall not take medication, which might impair their
sensory capacities.
Ability to Communicate: The ability of
candidates to communicate and describe the sensations they perceive when
judging a food product is particularly important.
Availability: Candidates shall
be available to attend both training and subsequent evaluation. Personnel who
travel frequently or have heavy workloads are often unsuited for sensory work.
ii.
Screening and Selection
Sensory panelists
can be screened and selected by adopting several tests. The followings are the
most commonly used tests:
- determine impairment of primary senses (colour, vision, ageusia and anosmia)
- matching test for taste and odour substances
- ability to detect basic taste and odour acuity
- determine ability to characterized texture
- performance in comparison with other candidates
a) Colour Vision: Candidates with
abnormal colour vision or colour blindness are unsuitable for judging of dairy
products. Assessment of colour vision can be carried out by a qualified
optician.
b) Matching Test: Samples of sapid
and/ or olfactory materials, depending on the nature of product for which the
panel members are to be trained later, at well above threshold levels of the
expected panelists are prepared. The examples of these materials are given in
table 10.1. Each sample is allotted a different, random, three digit code
number. Candidates are presented with one sample of each type and are allowed
to familiarize themselves with them. They are then presented with a series of
the same materials labelled with different code numbers. They may be asked to
match each of them with one of the original set and describe the sensation they
are experiencing. For the substances and their concentration given in table ,
candidates who make less than 80% correct answers should not be chosen as
selected panelists.
 |
| identification/ matching test |
* Stock solutions
are prepared with ethanol, but the final dilution is made with water and shall
not contain more than 2% of alcohol.
** To mask yellow
colour, present the solutions in closed opaque containers or under dim or
colouring light.
c) Test for Detection of Basic Taste:
Solutions of four basic taste solutions,namely sweet, sour, salt and bitter are
prepared of the concentration as shown in table below:
 | ||
| Concentration of Taste Solutions Used to Examine the Acuity of | Candidates |
These test
materials along with blank (water) are presented to the candidates and asked
them to detect the taste quality. Preferably candidates should have 100% correct
responses as the concentrations test materials are at the super threshold level.
Inability to detect differences and identify the taste quality after several repetitions
indicate that the candidates have poor sensitivity and are unsuitable to judge
the samples on the basis of taste.
d) Odour Recognition Test: Candidates
are presented many (about 10 in each lot) odoriferous substances. Some of these
materials are familiar (those we use daily such as tea, coffee, onion, garlic,
curd, orange, spices, etc.) and others unfamiliar (table 10.3). The odorous
food materials may be presented preferably in form of liquid extract or as such
(in a test tube in invisible form). The concentration should be above the
recommended threshold level. Candidates are graded according to correct
answers. Those recognize less than 65% of odorous substances/odour are
unsuitable as panelist for this type of test.
 | ||
| Examples of Unfamiliar Odorous Material for Odour Recognition | Test |
e) Textural Characterization:
This type of test is highly beneficial for selecting the panelists for judging
the dairy products where texture is an important attribute like cheese, paneer,
butter, ice cream, khoa etc. In this test, all range of products having typical
texture (table 10.4) is given to the candidates. They have to arrange these
products according to the nature and level of textural properties, such as hard,
elastic (spongy), adhesive (sticky/pasty), brittle, gummy, cohesive, chewy etc.
A satisfactory level of success in this task can be specified only in relation
to the products used. Candidates who achieve less than 65% of the maximum score
are unsuitable.
 |
| Food Products with Typical Textural Attributes |
iii.
Training
The purpose of
training is to increase sensory acuity of panelists and provide them with
rudimentary knowledge of procedures used in sensory evaluation. Training also
develop the ability of panel members to detect, recognize and describe sensory
stimuli related to dairy products. A general step-wise approach for training in
dairy product is summarized as below.
a) Sensory
panelists (assessors or evaluators) should be explained the basic requirements
of sensory evaluation i.e. what they should do and what not to do(already
explained in Unit 1).
b) Assessors shall
be acquainted with the:
- desirable and
undesirable attributes of the product
- correct
terminology
- use of score card
- scoring
technique/ sequence of observations
c) Samples used for
training and testing shall be characteristic of their origin, style and
quality, and representative of the range generally found in the market (all defects
may be simulated in the samples under laboratory conditions). Always provide a
reference (having most desirable characters) with test samples.
d) Adjust the
difficulties of the test so that the group as a whole will find difference between
the samples, but some panelists will fail
e) Start with the
large group and reject those who are insensitive or under perform.
f) Finally a
trained panel comprising of 5-6 members is retained.
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