This is part of a series called Wine Words, a glossary in the works that breaks down the barrier between those in the wine know and those who have no idea what the hell everyone's talking about. A new word posts once a week, covering everything from a grape name or region, to a winemaking or tasting term.
Lees (n.) Winemaking Term
Lees are the post-fermentation dead yeast cells that had previously been devouring grape sugars and converting them into alcohol.
Yeast + Sugar = Alcohol + CO2
There are gross lees, the larger coarser version, and fine lees, which are the more delicate parts and pieces of those deceased yeasts. The latter is often left to spend time with the fermented wine, bonding if you will, which adds body, mellows acids and in some cases, contributes a "yeasty" flavor reminiscent of fresh baked bread. Yum. A wine with this aroma might be described as "leesy."
In France, specifically Muscadet, the wine might be sur lie, which indicates that it sat on the lees for some time, a few weeks or maybe several months, before bottling. This sitting action (or non-action) happens in oak barrels, tank or in bottles, especially in the case of sparkling wine. For some wines, the lees are stirred, called bâtonnage in French, which will impart the same benefits as mentioned above but to a greater extent. In oak barrels, this practice can reduce the influence of oak on the wine, in a good way.
Long story short, wine spent on its lees has gained more nuance and interest. Here are some recent Pig&Vine recommendations that have chilled on their lees for a bit: