Autolysis is the breakdown of dead yeast cells by their own enzymes after fermentation. In winemaking, it is especially important during extended ageing on the lees in traditional-method sparkling wines such as Champagne. Autolysis can release compounds that contribute texture, complexity and aromas associated with bread, brioche, biscuit, pastry and nuts.
After fermentation, yeast cells die and settle as lees. During prolonged contact with the wine, enzymes gradually break down the yeast-cell structures and release mannoproteins, amino acids and other compounds. The rate and sensory effect depend on temperature, time, wine composition and cellar conditions.
In traditional-method sparkling wine, the wine remains in contact with the yeast sediment after the second fermentation in bottle. Extended lees ageing can contribute a creamy texture, finer integration and aromas of brioche, toast, biscuit and pastry. The wine is later riddled and disgorged to remove the sediment.
Some still wines are also matured on lees, particularly Chardonnay and Muscadet. Lees contact and bâtonnage can add texture and complexity, although the extent of autolytic character varies. The term should not be used to imply that every lees-aged wine has undergone the same degree of autolysis.
Example: Champagne aged for an extended period on its lees may develop brioche, biscuit and toasted-nut aromas alongside its fruit and acidity.
Autolysis results from the breakdown of yeast cells. Oxidation involves reactions with oxygen and can produce different changes in aroma, colour and flavour. The two processes may occur during maturation but are not the same.
Chef’s note: autolytic aromas can complement rich seafood, poultry, mushrooms and buttery sauces. Consider lees ageing alongside acidity and dosage when selecting sparkling wine for a menu.
This term is one of hundreds covered in depth across OCS courses, learning paths, and 1-on-1 coaching with Chef Eric.
