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July/August 2011
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Sensory Analysis

Discovering how differences between two different versions of a product will affect that product’s performance continues to be a challenge for sensory professionals. However, in the past 30 years, the testing method known as the tetrad test has emerged as a means of saving companies money by enabling more information to be extracted from smaller product tests.

ASTM International Committee E18 on Sensory Evaluation is currently developing a proposed new standard on the tetrad test, WK32980, Test Methods for Sensory Analysis — Tetrad Test. WK32980 is under the jurisdiction of Subcommittee E18.04 on Fundamentals of Sensory.

According to John Ennis, vice president, research operations, The Institute for Perception, and E18.04 chairman, when a company wishes to know whether two products perform differently, as occurs in advertising claims or when an ingredient change is being considered, difference testing is typically conducted internally. In a tetrad test, four samples, two from one version of the product and two from the other, are presented to a subject who is then asked to group the samples into two groups of two, based on similarity.

“The tetrad test has the remarkable property that the experiments needed to reliably detect differences using this method are potentially only one third to one half the size of the experiments needed to reliably detect differences using other existing methods,” says Ennis. “This fact is extremely important to companies that stand to gain millions of dollars through an effective ingredient substitution or to save millions of dollars by forgoing a change that would have resulted in a noticeably different product.”

Ennis notes that a common problem currently occurring in product testing is that, when attempting to use current methods, resources are often not available for the proper size test that would be needed to reliably detect differences. The proposed new standard would give companies an affordable test method that would allow them to make more informed decisions about potential product changes.

CONTACT

Technical Information: John M. Ennis, The Institute for Perception, Richmond, Va.

Phone: 804-675-2980

ASTM Staff: Scott Orthey

Phone: 610-832-9730