scope:

NEN-ISO 8588 specifies a procedure for determining whether a perceptible sensory difference exists between samples of two products. The method applies whether a difference exists in a single sensory attribute or in several.The "A" - "not A" test can be used in sensory analysis in the following ways: a)as a difference test, particularly for evaluating samples having variations, for example, inappearance (making it difficult to obtain strictly identical repeat samples) or in aftertaste (makingdirect comparison difficult); b)as a recognition test, particularly for determining whether an assessor or group of assessorsidentifies a new stimulus in relation to a known stimulus (for example, recognition of the quality ofthe sweet taste of a new sweetener); c)as a perception test, to determine the ability of an assessor to discriminate stimuli. The "A" - "not A" test is not appropriate for assessing if two products are sufficiently similar to be used interchangeably (i.e. for similarity testing) because the "A" - "not A" test inherently involves replicate evaluations of the same products by all assessors. These replicate evaluations violate the basic assumptions for similarity tests to be statistically valid. Examples of its application are given in Annex B.