autolysis, the destruction of the internal structures of cells by their own enzymes. In a winemaking context, the term most commonly applies to the action of dead yeast cells, or lees, after a second fermentation has taken place during sparkling winemaking. Its effects are greatest if wine is left in contact with the lees of a second fermentation in bottle for at least five years, and minimal if lees contact lasts for less than 18 months. mouthfeel is improved through the release of polysaccharides and peptides; oxidation is inhibited through the release of glutathione and reducing enzymes; and the production of certain mannoproteins reduces tartrate precipitation and improves protein stability. In addition, there is an increase in amino acids, which may be the precursors of those flavour characteristics typically associated with champagne such as acacia, biscuity or bready notes, and other complex aromas from bottle ageing.