Autolysis
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The impact of yeast autolysis should not be underestimated. The auto degradation of the cells and the concomitant increase of free amino nitrogen (FAN) possibly influence the formation of specific lactones during storage as are reported to be present in aged wines where they contribute to the specific aged flavor. A major consequence of yeast autolysis is the liberation of hydrolytic enzymes of the vacuole content in beer. This influences beer characteristics as flavor and foam stability by hydrolysis of hydrophobic proteins. The aroma is strongly affected by an increase of volatile fatty acids with a low threshold value. Due to cell autolysis, the concentration of isovaleric acid, caproic acid, caprylic acid, anc capric acid increases enough to develop a negative effect on the flavor. As a consequence, the drinker will notice a diminution of the fresh, fruity flavor when tasting aged beer.[1]
References[edit]
- ↑ Van Landschoot, A., et al. "Effect of pitching yeast preparation on the refermentation of beer in bottles." Cerevisia, vol. 29, no. 3, 2004, pp. 140–146.