8. The suitability of the tetrad test as a replacement for the triangle test in the brewing industry

Hannah Lemar (1); (1) Campden BRI, Nutfield, England

Technical Session 2: Sensory I
Sunday, August 14  •  9:45–11:30 a.m.
Tower Building, Second Level, Grand Ballroom

Traditionally, sensory teams in the brewing industry have focused on the popular triangle test for difference testing. However, the triangle test requires a relatively large number of tasters, which can be difficult for breweries with a limited number of tasters to achieve. In recent years, a number of novel difference test methodologies have emerged in the wider food and drink industry, including the tetrad. The tetrad protocol involves assessors being presented with four samples and then pairing the products based on similarity. Although there are 4 stimuli instead of 3, as in the triangle test, many papers have demonstrated that the tetrad test is consistently more precise than the triangle test equivalent. Despite the chance of guessing the correct answer being the same as for the triangle method (1/3), the tetrad test exhibits superior statistical power. This means that fewer panelists and smaller sample numbers are required, which reduces the cost and completion time. These benefits have created a great deal of interest in this method across the food and drink industries. For samples with high sensory complexity, like beer, it is thought that the extra stimuli required for a tetrad may cause sensory fatigue, reducing the validity of results produced. The aim of this project was to investigate if the tetrad could be a suitable substitute for the triangle test for the brewing industry. A secondary aim was to assess if the tetrad is more sensitive to particular differences. Panelists participating in this study were drawn from an expert trained profiling panel regularly tasting beer products and a second expert panel trained on difference tests. A total of 24 panelists was used for each triangle test and 12 panelists for each tetrad test. A wide range of products were assessed, with varying degrees and natures of differences. Each test was performed twice on each set of products. The results for the triangle and tetrads tests were comparable, despite the tetrad using half the number of panelists, indicating that the tetrad method could be a suitable alternative to the conventional triangle test for the assessment of beers. Results also suggest that the tetrad test is more effective at showing significant differences (P ≤ 0.05) between samples with small degrees of differences, reducing the chance of making a type II error, which is important when making commercial decisions.

Hannah Lemar received a B.S. degree in biology from the University of Manchester in 2010 and went on to complete a M.Med.Sci. degree in human nutrition from the University of Sheffield. Hannah joined Campden BRI in 2013 as a sensory analyst, running an expert tasting panel that specializes in beer, malt and other alcoholic beverages. She is currently in the process of completing a postgraduate certificate in sensory science with the University of Nottingham.