What condition leads to autolysis in yeast?

Autolysis in yeast primarily occurs due to the starvation of yeast cells. When yeast cells are deprived of nutrients, particularly essential ones, they begin to break down their own cellular components in a process known as autolysis. This self-digestion is a way for the cells to recycle nutrients internally, allowing them to survive until conditions improve.

During fermentation, as yeast consumes sugars and produces alcohol and CO2, it eventually exhausts its nutritional resources. When the yeast runs out of available sugars and other nutrients, the lack of food triggers autolytic processes. The accumulation of internal enzymes leads to the breakdown of cell membranes and the release of compounds that can contribute to flavor development in certain beer styles, particularly in those that benefit from a yeast-forward profile.

In contrast, increased sugar concentrations typically promote yeast activity rather than inducing autolysis, as yeast thrives on sugar to produce alcohol during fermentation. Excessive oxygen availability can lead to the development of off-flavors and oxidation but does not directly instigate autolysis. High temperatures may stress yeast and lead to various issues, but the direct cause of autolysis is more closely related to nutrient deprivation than temperature alone.