Lees Aging: Taking Wine to the Next Level

By Cole Swanson
November 27, 2024

Fermentation ends naturally when there is no more grape sugar for yeast to metabolize. Sugar is gone and the yeast remain, and at this point are considered lees. They are inactive but not ineffective. Their main job of creating alcohol is complete. But if a winemaker wants to have a little fun and add texture, complexity, and additional flavors to their wine, they may incorporate what is known as extended lees aging or as the French say, “sur lie” (on the lees).

Texture, Complexity, Flavor

Most commonly, lees stirring adds richness, creaminess, and can make the wine fuller-bodied, which is the result of a chemical process called autolysis. Think Champagne. By law, true Champagne must age on lees in the bottle before it can be sold for consumption. After this aging period, the wine may have notes of bread, toast, and honey, in addition to adding weight to the wine’s body by providing a creamy, silky texture.

Common Wines That Implement Lees Aging

Pinot Noir: the use of lees helps to reduce astringency or bitterness of pinot noir while leading to a fuller-bodied wine that has more complex flavors, helping the wine to age.

Chardonnay from Burgundy, France: Chardonnay from Burgundy, specifically the region of Chablis, is world-renowned for being high quality. Due to the cool climate, it is naturally higher in acidity and lighter in body than California, giving it great potential for aging. The addition of lees aging helps with aging potential because yeast autolysis helps to provide creamier textures, which adds body and weight in addition to more savory flavors.

Melon de Bourgogne: This is the grape varietal used to create white wines in Muscadet, a region in the Loire Valley, France, where the most common white wine is made from Melon de Bourgogne. This varietal is typically meant to be drunk while young (meaning shortly after being bottled), and can be very bright with citrus notes. But the addition of lees imparts flavors otherwise not found in this varietal, while also increasing its aging potential. The result has been wines that score very well in competitions.

The Types of Lees

There are two types of lees – gross and fine. The term “gross lees” coincidently describes how a wine would taste if these clumps of yeast were not filtered out. Therefore, filtration is completed immediately after fermentation to avoid imparting off-putting flavors. Smaller clumps of lees, known as fine lees, also float in the wine and gradually sink to the bottom before being filtered. But it is this type of lees that the winemaker may use to implement additional texture and complexity by stirring them for full integration prior to filtration.

This stirring, referred to in France as “battonage,” allows for flavors to mesh with the newly-fermented wine. It can take a while for fine lees to fully incorporate themselves, but when they do, they provide additional flavors and absorb tannins and oxygen.