Autolysis (alcohol fermentation)

Autolysis in winemaking relates to the complex chemical reactions that take place when a wine spends time in contact with the lees, or dead yeast cells, after fermentation.The chemical process and details of autolysis were not originally understood scientifically, but the positive effects such as a creamy mouthfeel, breadlike and floral aromas, and reduced astringency were noticed early in the history of wine.Studies have shown that the chemical reaction of autolysis, and its impact on the wine, starts to become noticeable after 18 months and will continue to impart traits for at least 5 years.The increased production of amino acids leads to the develop of several flavors associated with premium Champagne including aromas of biscuits[6] or bread dough, nuttiness[7] and acacia.If the layer of lees begins to exceed 4 inches (10 centimeters), the enzymes released from the process of the yeast digesting themselves creates reducing conditions and promotes the development of hydrogen sulfide and mercaptan odors.
Many of the flavors associated with premium Champagne are influenced by the autolysis of the lees during winemaking.
As the Champagne ages on its lees (pictured inside bottle) the process of autolysis causes the release of mannoproteins and polysaccharides that influence the flavor of the wine.
Autolysis (biology)winemakingfermentationChampagnesur lieRoman winemakingastringencyhistory of wineAncient RomanMarcus Porcius CatoAppellation d'origine contrôléevintageChampagne housesethanolsuch as nitrogenrackingenzymesmannoseglycoproteinspolysaccharidessparkling wine productionsecondary fermentationwine bottleriddlingfuller bodyoxidationaging potentialtartratestanninsamino acidsbiscuitsnuttinessacaciawine faultsreducinghydrogen sulfidemercaptanfungicidesulfideWayback MachineJancis RobinsonThe Oxford Companion to WineOxford University Press