Improved Flavor Stability by Aging Beer in the Presence of Yeast

Abstract

Unwanted flavor changes occur during beer storage. Because yeast has a large reducing activity on aging compounds, the aim of this study was to examine the effect of refermentation on flavor stability. It was shown that the addition of yeast to aged beer removed aged flavor almost completely. Furthermore, the addition of yeast to fresh beer decelerated beer aging considerably. Both a top-fermenting and a bottom-fermenting yeast strain were able to exert this effect, and it was clear that initiation of a real refermentation process by adding sugar was not required. Finally, several yeast concentrations were tested, and it appeared that even adding an amount as low as 10,000 yeast cells/mL was sufficient to slow beer aging. Nonetheless, the effect was more pronounced when higher concentrations were used.