Discrimination of Isointense Bitter Stimuli in a Beer Model System.

Molly J Higgins,John E Hayes

doi:10.3390/nu12061560

Abstract

Prior work suggests humans can differentiate between bitter stimuli in water. Here, we describe three experiments that test whether beer consumers can discriminate between different bitterants in beer. In Experiment 1 (n = 51), stimuli were intensity matched; Experiments 2 and 3 were a difference from control (DFC)/check-all-that-apply (CATA) test (n = 62), and an affective test (n = 81). All used a commercial non-alcoholic beer spiked with Isolone (a hop extract), quinine sulfate dihydrate, and sucrose octaacetate (SOA). In Experiment 1, participants rated intensities on general labeled magnitude scales (gLMS), which were analyzed via ANOVA. In Experiment 2, participants rated how different samples were from a reference of Isolone on a 7-point DFC scale, and endorsed 13 attributes in a CATA task. DFC data were analyzed via ANOVA with Dunnett’s test to compare differences relative to a blind reference, and CATA data were analyzed via Cochran’s Q test. In Experiment 3, liking was assessed on labeled affective magnitude scales, and samples were also ranked. Liking was analyzed via ANOVA and rankings were analyzed with a Cochran–Mantel–Haenszel test. Experiment 1 confirmed that samples were isointense. In Experiment 2, despite being isointense, both quinine (p = 0.04) and SOA (p = 0.03) were different from Isolone, but no significant effects were found for CATA descriptors (all p values > 0.16). In Experiment 3, neither liking (p = 0.16) or ranking (p = 0.49) differed. Collectively, these data confirm that individuals can discriminate perceptually distinct bitter stimuli in beer, as shown previously in water, but these differences cannot be described semantically, and they do not seem to influence hedonic assessments.

Highlights

Bitterness is classically considered to be monogeusic, and bitter stimuli that lack other side tastes are traditionally labeled with a singular semantic label in English that lacks any additional subgroupings
The lower concentration of Isolone (0.011%) was equi-intense with the quinine and sucrose octaacetate (SOA) beers for all attributes, so these samples and concentrations were used for Experiments 2 and 3
The results of Dunnett’s test indicate that the quinine- and SOA-spiked beers were both rated as being significantly different from this blind reference, indicating that both quinine and SOA can be differentiated from Isolone in a difference from control (DFC) task

Summary

Introduction

Bitterness is classically considered to be monogeusic (i.e., one singular, indistinguishable percept), and bitter stimuli that lack other side tastes are traditionally labeled with a singular semantic label in English (i.e., bitter) that lacks any additional subgroupings. Research over the past quarter century suggests that bitterness may be multigeusic [1,2,3,4]. These prior studies suggest bitter stimuli dissolved in water can be discriminated by humans. Learning to like one type of bitter (e.g., hops in beer) may not generalize to another type of bitter (e.g., quinine in tonic water) if the neural code for these bitters remains distinct despite a common semantic label. We tested whether self-reported beer consumers could discriminate between three bitter stimuli believed to be perceptually distinct

Results

Discussion

Conclusion