AS 2542.2.2:2014 pdf free.Sensory analysis Part 2.2: Methodology—Triangle test.
5 General test conditions and requirements
5.1 Clearly define the test objective in writing.
5.2 Carry out the test under conditions that prevent communication among assessors until all the evaluations have been completed, using facilities and booths that comply with ISO 8589.
5.3 Prepare the samples out of sight of the assessors and in an identical manner (i.e. 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. For example, in a taste test, avoid any differences in appearance. Mask any irrelevant colour differences using light filters and/or subdued illumination.
5.5 Code the vessels containing the samples in a uniform manner, preferably using three-digit numbers, chosen at random 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 be used for all assessors within a test, provided that each code is used only once per assessor during a test session (e.g. if several triangle tests on different products are being conducted in the same session).
5.6 The quantity or volume served shall be identical for the three samples in each triad, just as that of all the other samples in a series of tests on a given type of product. The quantity or volume to be evaluated may be imposed. If it is not, the assessors should be told to take quantities or volumes that are always similar whatever the sample.
5.7 The temperature of the three samples in each triad shall be identical, just as that of all the other samples in a series of tests on a given type of product. It is preferable to present the samples at the temperature at which the product is generally consumed.
5.8 The assessors shall be told whether or not they are to swallow the samples or whether they are free to do as they please. In this latter case, they shall be requested to proceed in the same manner for all the samples.
5.9 During the test sessions, avoid giving information about product identity, expected treatment effects, or individual performance until all testing is completed.
6 Assessors
6.1 Qualification
All assessors should possess the same level of qualification, this level being chosen on the basis of the test objective (see ISO 8586-1 and ISO 8586-2 for guidance). Experience and familiarity with the product may improve the performance of an assessor and, therefore, may increase the likelihood of finding a significant difference. 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 and evaluation procedure).
6.2 Number of assessors
Choose the number of assessors so as to obtain the sensitivity required for the test (see the discussion in A.3). Using large numbers of assessors increases the likelihood of detecting small differences between the 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 testing for a difference, typical numbers of assessors are between 24 and 30. When testing for no meaningful difference (i.e. similarity), twice as many assessors (i.e. approximately 60) are needed for equivalent sensitivity.AS 2542.2.2 pdf download.