Discriminative tests

Food Standard and Quality Control

Lesson 12 : Subjective Methods

Discriminative tests

  1. Paired comparison:

    The method is applicable whether a difference exists in a single sensory attribute or in several, which means that it enables determination of whether there exists a perceptible difference concerning a given attribute, and the specification of the direction of difference, but it does not give any indication of the extent of that difference. The absence of difference for the attribute under study does not signify that there does not exist any difference between the two products.

    This method is only applicable if the products are relatively homogeneous. The method is effective for determining whether a perceptible difference exists or whether no perceptible difference exists when, for example, a stored snack product for desired period.

  2. Specimen evaluation card for Paired Comparison Test


  3. Preference test:

    Preference tests allow consumers to express a choice between samples; one sample is preferred and chosen over another or there is no preference. These types of tests supply information about people's likes and dislikes of a product. They are not intended to evaluate specific characteristics, such as crunchiness or smoothness.

  4. Difference testing:

    Tests for difference are designed to determine whether two samples can be distinguished from each other by sensory analysis. Difference tests can be used to determine whether a noticeable change has occurred in a food's appearance, flavour, or texture as a result of storage, of a change in processing methods, or of alteration of an ingredient.

  5. Multiple Sample Difference Test:

    In this test, more than one test variable can be evaluated in each session. Each panelist is served 3-6 samples depending upon the number of test variables. One among them is known standard. The panelist comĀ­pares each coded sample with the known standard. One coded sample is a duplicate of the standard. The score assigned to the blind standard is subtracted from the score assigned to the test variables..

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  7. Duo-tri test:

    A Duo-Trio Test is an overall difference test which will determine whether or not a sensory difference exists between two samples. This method is particularly useful to determine whether product differences result from a change in ingredients, processing, packaging, or storage. And also to determine whether an overall difference exists, where no specific attributes can be identified as having been affected.

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  9. Triangle test:

    It is a form of difference test that is commonly used to determine whether there are perceptible differences between two samples. The size and direction of difference between two samples, however, will not be specified in this test. To test for discrimination of differences related to one characteristic, the samples being compared must be identical in all other characteristics. Other tests, such as the paired-comparison or duo-trio test can be used for similar purposes.

  10. Ballot for bean storage pretreatment triangle test


  11. Ranking test:

    This test isĀ· used to determine how several samples differ on the basis of a single characteristic. A control need not be identified. Panelists are presented all samples simultaneously (including a standard or control if used) with code numbers and are asked to rank all samples according to the intensity of the specified characteristic. In consumer analysis, the panelists are asked to rank the coded samples according to their preference.

Last modified: Friday, 17 February 2012, 10:03 AM