AS 2542.1.1:2014 pdf – Sensory analysis Part 1.1: Methodology-Generalguidance.
Hunger and satiety can influence an assessor’s performance, and, if panels are held too frequently, performance may deteriorate. If it is possible, assessors should be asked to refrain from smoking and from consuming snacks such as coffee for 1 h before a test, Assessors should not carry any foreign odours into the session, for example tobacco or cosmetic odours, as these could influence the responses of other assessors,
The time of day at which the test is conducted is important. The schedule should take into account local customary mealtimes since performance is generally considered optimum at mid-morning and mid-afternoon. Assessors suffering from emotional upsets, colds and other illnesses should be excluded from tests until they recover.
The collation of the results comprises three aspects:
checking that all data have been recorded accurately, either on computer or manually;
verification that any additional relevant information which may aid or cast doubt on the interpretation of the results has been noted;
— checking that the assessors are motivated to continue participating if further testing is planned.
5 Methods of test
5.1 General
The most commonly used tests are divided into three groups:
a) discrimination tests used to determine the probability of difference or similarity between products (see 5.2);
b) tests using scales and categories to estimate the order or size of differences or the categories cx classes to which samples should be allocated (see 5.3);
c) descriptive tests used to identify the specific sensory attributes present in a sample (see 5.4).
For the number of assessors, refer to the corresponding standards, taking into consideration a or /1 risk depending on the purpose of the test. Alternatively, sequential analysis (see ISO 16820) may allow a decision to be made after fewer trials of the test than would be required by conventional approaches that use a predetermined number of assessments.
The tests may also be quantitative.
5.2 Discrimination tests
5.2.1 General
The following tests are commonly used to determine the probability of difference or similarity between samples:
a reference. It is especially suitable when the reference sample is well known to the assessors, for example a sample of regular production.
If there are after-tastes, this test is less suitable than the paired comparison test (5.2.2) or the “A — not A” test
(5.26). Procedure
The assessors are first presented with the identified reference sample. This is followed by two coded samples,
one of which is identical to the reference sample. The assessors are asked to identify this sample. Analysis of results
See 6.2.4.
5.2.5 Two-out-of-five test DefinitIon
This is a discrimination test involving five coded samples, two of which are of one type and three of another.
The assessors are asked to group the two sets of samples. Application
The two-out-of-five test is recommended to establish a difference more economically than other tests (the method is statistically more efficient).
The disadvantages of this test are similar to those of the triangle test (5.2.3). It is more strongly affected by sensory fatigue and memory effects but has greater statistical power. Its principal use is in visual, auditory or tactile applications. Procedure
The assessors are each presented with one set of five coded samples and are told that two are of one type and three of another. The assessors are asked to group the two sets of samples.
When the number of assessors is less than 20, the order of presentation should be selected at random from the following 20 distinct permutations:
See 6.2.5.
5.2.6 “A — not A” test Definition
This is a test in which a series of samples, which may be “A or “not A”. is presented to the assessors after they have learnt to recognize sample A”. The assessors are asked to indicate which sample is MA’.
See ISO 8588 for details.