Influence of beer color on perception of bitterness

Joseph William Spearot

doi:10.17918/etd-6613

In general, beer is composed of malted barley, hops, water, and yeast. The color of beer derives in large part from malted barley, which also provides sugars for alcoholic fermentation by yeast. Meanwhile, bitterness in beer derives almost entirely from the main flavoring agent: hops, which also give the product fruity, woody, herbal, and spicy flavor notes. Thus, flavor and color in beer - particularly bitter taste - are not connected. Nevertheless, the idea that beer color predicts flavor intensity is common among consumers. This is probably due to sociohistorical factors. For example, in the 19th century companies like Miller and Anheuser- Busch began to, and still do, dominate the brewing market with German-style lagers with low alcohol, low bitterness, and light colors. Perhaps because of this there is a common misconception that a darkcolored beer will be more bitter than a lighter beer. The current research was designed to investigate whether this common misperception will result in measurable differences in consumer sensory perception. All of the research below was approved by the Drexel University IRB. First, a discrimination study on methods for creating dark color in beers was completed to determine whether these adjuncts created perceptible differences in beers when consumers were blind to color. Three batches of beer from the same recipe were brewed; one batch was darkened with black malt (~4% total grain bill w/w), one was darkened with Sinamar®, a malt-based dye (120 mL per 19 L beer), and the third was uncolored. A series of triangle tests (n = 24) was carried out between the samples with color concealed; in addition, bitterness (IBU) and color (SRM) were quantified instrumentally. Tests confirmed that the only difference between samples was color. From these results, Sinamar® was chosen as a darkening method for the main test; a triple batch of the same recipe was brewed, split into three, and colored to three levels: yellow (SRM = 13.0), brown (SRM = 30.7), and black (SRM = 55.1). A second set of triangles tests (n = 21) found no differences between these beers. A consumer sensory test (n = 85) collected data on these beers' flavors with color unobscured. Data were analyzed using repeated-measures ANOVA, with consumers as between-variables and beer- color as within-variables. This analysis showed that consumers rated the yellow beer samples as significantly (F (2, 164) = 5.15; p < 0.05) more bitter than the black beer samples, although the same samples are not readily discriminable when color is obscured. This is evidence of a significant color/taste interaction in beers. The direction of this interaction, however, was unexpected: this may be due to the rise in popularity of India Pale Ale styles; these are light, yellow beers with intense hop bitterness. To examine this hypothesis further, posthoc investigation of demographic trends in color-bitterness interactions were explored and are presented here.

Influence of beer color on perception of bitterness

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Influence of beer color on perception of bitterness

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