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. At this point, the remaining yeast are considered lees, of which there are two twpes, “gross lees” and “fine lees.”

Fine lees are champions of adding levity to the wine, and are the ones winemakers may choose to preserve before removing the wine from the tank in which it was fermented. By doing so, they will be incorporating additional texture, complexity, and flavors. This techinque is known as extended lees aging or as the French say, “sur lie” (on the lees).

THE TYPES OF LEES

Gross Lees

The term “gross lees” coincidently describes how a wine would taste if these clumps of yeast were not filtered out.

They are not actually “yeast,” rather larger clumps of debris, such as any grape skins, seeds, or reminents of the harvesting process like twigs or dirt. Therefore, these types of lees are left to sink to the bottom of the tank, where they will be filtred to avoid imparting off-putting flavors.

Fine Lees

Fine lees are actually yeast.

They float in the wine and will sink to the bottom of the tank as well, but do so more gradually. Before removing fine less, the winemaker may consider using them to implement additional texture and complexity by stirring them for full integration.

This stirring, referred to in France as “battonage,” allows for additional 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 complexity and absorb tannins and oxygen.

TEXTURE, COMPLEXITY, FLAVORS

Most commonly, lees stirring adds richness, creaminess, nuttiness, and provides wines with more body or weight.

Another common result of this process is flavors of bread, brioche or toast. This is the result of a chemical process called autolysis, which is what provides a wine like Champagne with its bread-y flavors.

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, while also imparting creaminess and a silky texture.

Dry Riesling may also see less aging. Because it has been fermented to driness, the body of the wine will typically be lighter. Should the winemaker allow lees to remain in the wine, the body will become fuller.

There is no standard amount of time lees are aged in a wine — it is entirely up to the winemaker. In the case of Champagne, sometimes the bubbly will mingle with lees for years.

COMMON WINES THAT INCORPORATE LEES AGING

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.

Pinot Noir

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.