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.
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