Decrease in hydrogen sulfide content during the final stage of beer fermentation due to involvement of yeast and not carbon dioxide gas purging
2008
Oka, Kaneo | Hayashi, Teruhiko | Matsumoto, Nobuya | Yanase, Hideshi
We observed a rapid decrease in hydrogen sulfide content in the final stage of beer fermentation that was attributed to yeast and not to the purging of carbon dioxide (CO₂) gas. The well known immature off-flavor in beer due to hydrogen sulfide (H₂S) behavior during beer fermentation was closely investigated. The H₂S decrease occurred during the final stage of fermentation when the CO₂-evolution rate was extremely small and there was a decrease in the availability of fermentable sugars, suggesting that the exhaustion of fermentable sugars triggered the decrease in H₂S. An H₂S-balance analysis suggested that the H₂S decrease might have been caused due to sulfide uptake by yeast. Further investigation showed that the time necessary for H₂S to decrease below the sensory threshold was related to the number of suspended yeast cells. This supported the hypothesis that yeast cells contributed to the rapid decrease in H₂S during the final stage of beer fermentation.
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