Date of Award
Master of Science
Food Science and Technology
Marjorie P. Penfield
David A. Golden, Arnold M. Saxton
The triangle method has been widely used in the food industry for many years when conducting sensory discrimination testing. Recently, however, another discrimination testing method, the tetrad, has begun to gain popularity. Based on currently published research, the tetrad method possesses statistical advantages over the triangle and would require fewer panelists, reduce testing time, and use less sample material. More testing is needed to confirm these advantages in an applied, industrial approach on a wider range of products. Over thirty triangles and thirty tetrads with untrained panelists have been completed in order to compare the two methods. Products tested ranged from canned vegetables and fresh fruits to deli meats and baked goods. Panels conducted thus far have provided contradictory results. Inconsistencies have been found within and across product categories. Significant differences were seen with the triangle method but not in the tetrad in a few cases. In one specific instance, the same products were tested alone and then again with a carrier. Panelists were able to perceive the difference between the products with both methods when the product was served alone but were unable to do so when a carrier was present with the tetrad. Effect size and test power for each test were also calculated and produced similar results. In eight of the experiments completed, the reduction in effect size for the tetrad offset the statistical power advantage, making the triangle method more beneficial for these products. Significant differences (p < 0.05) were found between methods when the degree of difference was measured between samples for each test with a larger difference found using the triangle in a few cases. Participating panelists were also asked to compare the two methods in terms of difficulty on a structured scale and in an open-ended fashion. Overall, panelists perceived the two methods as very similar in terms of method difficulty with very little mean separation between experiments. Panelists noted that the product being tested affected their impression of the tests in multiple experiments.
Carlisle, Sara Lyn, "Comparison of Triangle and Tetrad Discrimination Methodology in Applied, Industrial Manner. " Master's Thesis, University of Tennessee, 2014.