Triangle sensory difference tests

Analytical methods can be sub-divided into difference tests and descriptive analysis. Difference tests such as triangle and paired comparison tests are designed to identify differences between samples. In a triangle test, the assessor is given three samples, two of which are the same, and asked to identify which sample is different. In a paired comparison test, the assessor is asked to identify whether there is a difference in a particular sensory characteristic between a pair of samples. Descriptive analysis, in which the sensory characteristics of a sample are described and scored on a scale, is probably the most important analytical method. 

Lynch et al. (2005) compared the flavor, organoleptic and storage characteristics of standard 2%-fat milk with 2%-fat milk that had an approximately 10-fold higher level of CLA. The naturally enhanced milk (the level of CLA and VA was 47 and 121 mg/g fatty acids, respectively) was produced through individual selection and nutritional management of the cows. Initial evaluation of the milk and evaluation over a 14-day postpasteurization period indicated no flavor differences as determined by triangle taste tests. Similarly, sensory results indicated no differences in susceptibility to the development of oxidized off-flavors between the control and CLA-enhanced milks, even when milk was stored under light (Lynch et al., 2005). Thus, flavor and consumer acceptability were maintained in a dairy product with substantially enhanced levels of CLA and VA. 

The triangle test allows the sensory analyst to determine if two samples are perceptibly different, but not in which attributes the samples differed. 

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