- Grape solids and dead yeast cells that have precipitated to the bottom of the tank or barrel during ageing. Can contribute to complexity, and facilitates malolactic fermentation.
Properly managed, lees add unique and desirable character, but if the winemaker is not careful, the yeast cells can begin to deteriorate, a condition called autolysis. An autolytic wine can show a number of undesirable odours including ‘beery’, ‘bready’, hydrogen sulphide, and a group of nasties called mercaptans.
You may come across a bottle that says ‘bottled on lees’. This means that the wine was transferred directly from the barrel to the bottle, without filtering. The wine may even show a trace of cloudiness, which in this case is a bonus.