ISO 4120-2021 pdf free download – Sensory analysis — Methodology — Triangle test.
5.3 Prepare the samples out of sight of the assessors and in an identical manner (e.g. same apparatus,same vessels, same quantities of product).
5.4 Assessors shall not be able to identify the samples from the way in which they are presented.Forexample, in a taste test, avoid any differences in appearance.Mask any irrelevant colour differences usinglight filters and/or subdued illumination.
5.5 Code the test samples in a uniform manner, preferably using three-digit numbers, chosen atrandom for each test. Each triad is composed of three samples, each with a different code. Preferably,different codes should be used for each assessor during a session.However,the same three codes may beused for all assessors within a test, provided that each code is used only once per assessor during a testsession (e.g. if several triangle tests on different products are being conducted in the same session).
5.6lt is preferable to present the samples under the conditions at which the product is generally used(e.g.in a taste test, present the samples at the temperature at which the product is generally consumed).The serving conditions of the three samples in each triad shall be identical (e.g. in a taste test, the threesamples shall be served at the same temperature), just as that of all the other samples in a series of testson a given type of product.
5.7The size, quantity or volume presented shall be identical for the three samples in each triad, just asthat of all the other samples in a series of tests on a given type of product. The size, quantity or volume tobe evaluated may be imposed. lf it is not, the assessors should be told to take sizes, quantities or volumesthat are always similar whatever the sample.
5.8ln a taste test, the assessors shall be told whether or not they are to swallow the samples orwhether they are free to do as they please. In this latter case, they shall be requested to proceed in thesame manner for all the samples.
5.9During the test sessions, avoid giving information about product identity, expected treatmenteffects, or individual performance until all testing is completed.The only necessary information for theassessor is the nature of the product to be tested and the task to be performed.
6Assessors
6.1Qualification
All assessors should possess the same level of qualification, this level being chosen on the basis of thetest objective (see ISo 8586 for guidance).Experience and familiarity with the product may improvethe performance of an assessor and, therefore,may increase the likelihood of finding a significantdifference.Monitoring the performance of assessors over time may be useful for increased sensitivity.All assessors shall be familiar with the mechanics of the triangle test (i.e. format,task andevaluation procedure).
6.2 Number of assessors
Choose the number of assessors so as to obtain the sensitivity required for the test (see the discussion inA.3). Using large numbers of assessors increases the likelihood of detecting small differences betweenthe products.However, in practice, the number of assessors is often determined by material conditions(e.g. duration of the experiment,number of available assessors, quantity of product). When testingfor a difference, typical numbers of assessors are between 24 and 30.When testing for no meaningfuldifference (i.e. similarity), twice as many assessors (i.e. approximately 60) are needed for equivalentsensitivity.
Avoid replicate evaluations by the same assessor whenever possible. ISO 4120 pdf download.