Autolysis

The decomposition of spent yeast cells after fermentation is complete. When a wine is left sur lie, or on the lees, it remains in contact with the spent yeasts that performed the fermentation. As the yeasts’ cell walls collapse, enzymes start to break down the cells themselves, producing mannoproteins and polysaccharides that are released into the wine. These impart an extra dimension of flavor, texture, viscosity, and complexity.