ISO 4120:2021 pdf download.Sensory analysis一Methodology一Triangle test
1 Scope
This document specifies a procedure for determining whether a perceptible sensory difference or similarity exists between samples of two products. The method is a forced-choice procedure. The method is applicable whether a difference exists in a single sensory attribute or in several attributes.
The method is statistically more efficient than the duo-trio test (described in ISO 10399), but has limited use with products that exhibit strong carryover and/or lingering flavours.
The method is applicable even when the nature of the difference is unknown [i.e. it determines neither the size nor the direction of difference between samples, nor is there any indication of the attribute(s) responsible for the difference]. The method is applicable only if the products are homogeneous.
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 ilumnination.
5.5 Code the test 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 It 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 three samples shall be served at the same temperature), just as that of all the other samples in a series of tests on a given type of product.
5.7 The size, quantity or volume presented 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 size, quantity or volume to be evaluated may be imposed. If it is not, the assessors should be told to take sizes, quantities or volumes that are always similar whatever the sample.
5.8 In a taste test, 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. The only necessary information for the assessor is the nature of the product to be tested and the task to be performed.ISO 4120 pdf download.