N. DOI (1), M. Kobayashi (1), S. Masuda (1), M. Aizawa (1);
(1) Asahi Breweries, Ltd., Ibaraki, Japan
Technical Session 4 - Flavor and Product Stability I
Monday, June 15
10:45 a.m.–12:00 p.m.
Fiesta 3,4,6,8
The perceived quality of beer is heavily based on its flavor; therefore, flavor is one of beer’s most important components. Among the most important flavors associated with beer, a metallic taste, even if present in trace amounts, imparts a certain unpleasantness to the consumer. Although a number of compounds have been reported to contribute to a metallic flavor in beer and other alcoholic beverages such as wine, none have been identified as the primary cause. In this study, to identify which compound is primarily responsible for the metallic flavor in beer, we investigated the concentrations and odor thresholds of several compounds previously reported as contributors. Using gas chromatography–olfactometry and gas chromatography–mass spectrometry, we identified the following three compounds as the main imparters of a metallic flavor: 1-octen-3-one (OEO); 1,5-octadien-3-one (ODO); and 4,5-epoxy-2-decenal (epoxy). The reason that none of these compounds have previously been identified as the primary cause of a metallic flavor is that their concentration and odor thresholds in beer are too low. Our analysis revealed that the concentrations of ODO and epoxy in fresh beer were lower than their odor thresholds; conversely, the concentration of OEO was higher than its odor threshold. These results suggest that in fresh beer, OEO is the compound primarily responsible for the metallic flavor and that the other compounds we identified as contributors do not impart a metallic flavor to fresh beer independently. Further analysis also revealed that the concentration of epoxy increased during beer storage. The concentration of epoxy in aged beer was higher than its odor thresholds. This result suggests that epoxy is also responsible for the metallic flavor in aged beer.
Norio Doi has been a researcher in the Research & Development Laboratories for Alcohol Beverages at Asahi Breweries, Ltd. since 2009. In 2009, he received his M.Eng. degree in polymer chemistry from Kyoto University, where he focused on tissue engineering.
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