Difference Testing

Difference testing is used to determine if foods differ in certain aspects. Some of these aspects include, but are not limited to, odor, taste, and texture. The sensory lab employs four different types of difference tests: the tetrad test, the triangle test, the duo-trio test, and the paired comparison test.

The tetrad test is used to determine if there is a difference between two products by tasking panelists with grouping four samples into two groups of two. This method is useful for a wide variety of products including those with more variability. This test is more statistically sound, allowing for significant data with fewer panelists. This method is useful for a wide variety of products including those with more variability. This test is more statistically sound, allowing for significant data with fewer panelists.

The triangle test is employed when the test objective is to determine whether detectable sensory differences exist between two products, and is especially useful when production changes may have produced product changes. Panelists taste the three samples and indicate which sample is different. The triangle test is more statistically efficient than duo-trio and paired comparison tests based on probability of choosing a correct result simply by guessing. This test may not be the correct choice, however, when there are significant carryover flavors between samples, and panelists are confused by three samples to evaluate rather than two.

The duo-trio test is also used to detect product differences that may result from ingredient supplier changes, storage, packaging, etc. Panelists indicate the sample that is identical to a given reference sample. It is simple and easily understood.

Paired comparison tests are used to indicate which of two samples has more of an attribute being tested, or to indicate which of two samples is preferred. In the latter application, it is considered to be an acceptance test. It is one of the most used attribute difference tests, and is easy for panelists to understand.