In enology, «grands crus» white wines are traditionally aged by the «sur lies» method, which consists of keeping the aging wine in contact with the lees (yeasts and organic residues). The lees can come either from the first or second fermentation and can be used for both white and red wines. This practice is still in the experimental stage. We reviewed scientific studies carried out on wine lees to determine the current situation in enology. We also provide some technological information relevant to such a practice.
The first part of this paper provides a clear definition of wine lees from a legal and technological point of view. The second part describes the mechanisms of autolysis and focuses on each class of autolysis product. Many scientific studies have discussed the phenomenon of yeast autolysis during wine ageing. Most of these studies simply identified the yeast macromolecules released into the wine during autolysis. However, the experimental methods used vary and it is difficult to extrapolate most of results to the process of wine ageing on lees. Only a few studies have dealt with the physicochemical properties of lees during autolysis, especially concerning oxygen, polyphenols and other wine compounds. We then summarize the recent data obtained on these topics. Finally, we discuss the technical effects of aging wine on lees.