Prior studies in our laboratory explored the effect of glass color on preventing International Bitterness Unit (IBU) reduction and taste effects in beers exposed to UV light. When beer is exposed to UV light it attains an off-flavor sometimes termed “light struck” and brown bottles were shown to minimize the effect on both flavor characteristics and IBU reduction when compared to clear or green bottles. As an extension of this work we explored whether other environmental factors could contribute to IBU changes in beer. For this work, samples of a commercial West Coast Style IPA either underwent constant refrigeration, repeated hot/cold cycling over a six day period or exposure to air in the dark for 150 minutes. Six samples for each experimental group underwent one of these three treatments and IBU values were subsequently measured using a manual, organic extraction method. The samples that underwent constant refrigeration had IBU values of 49.97 ± 0.73 while the hot/cold cycling samples had IBU values of 51.62 ± 1.06 and the air exposed samples had IBU values of 50.03 ± 0.56. Most importantly, our data demonstrate that the IBU reduction associated with UV light exposure cannot be due to concomitant exposure to air. Additionally, while both hot/cold cycling and exposure to air are known to affect the flavor of beer this apparently cannot be due to a reduction in IBU values. Future work may include studying the effect of excessive shaking or using a sensory panel to compare the taste profiles of samples exposed to the treatments used in this study.

Effect of hot/cold cycling and air exposure on beer IBU values

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.