Every style of beer is unique when defined by its body, flavor, and aroma. One of the major contributors to flavor and aroma is ethanol itself. A long standing question in brewing science is how to brew a beer that contains less alcohol per volume but still maintains its unique flavor and aroma profile. The purpose of this project is to create a strain of brewing yeast that will favor aerobic metabolism over anaerobic fermentation, thus producing a beer of similar flavor and aroma profile, but with lower than normal ethanol concentrations. A yeast with this ability would have great commercial application as it could represent a path to producing beers that satisfy the craft brewing market while avoiding some of the impacts on personal and community health that beverages with high ethanol content can have. For this study, Saccharomyces cerevisiae strains of brewing yeast were used. The yeast were mutagenized, plated out a media selective and fatal for yeast with a functioning copy of the alcohol dehydrogenase enzyme, and left to grow for 11-14 days at 30oC. Once colonies had grown, individual colonies were picked from the plates and grown in 25 mL of nutrient rich broth at 30oC for 2-3 days. Cell counts were then performed and the yeast were pitched into pre-prepared wort at approximately 1x106 cells per mL of wort and then used in pilot fermentations where initial gravity, final gravity, and % Brix readings were taken in addition to an ethanol concentration measurement at the end of the fermentation. We have obtained reductions in ethanol production as high as 0.8% ABV, which represents nearly a 25% decrease in relative ethanol concentration under test fermentation conditions. This project is ongoing and fermentation data in continued to be collected

Decreasing ethanol production in Saccharomyces cerevisiae through mutagenesis of alcohol dehydrogenase enzyme

251st National Meeting (2016)

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