A very common mistake that I see, over and over again (most especially by writers who are new to wine) is the statement of “Sur Lees Aging.” This is incorrect usage of the process.
Sur lie is a process of aging. It allows for a wine, when it’s finished fermenting, to sit on the lees while flavor is extract. When the wine is aging on lots of these tiny yeast cells (lees), it’s called the Sur Lie process.
Lees are the residue of dead yeast cells, which form in wine during fermentation. Lees may also contain grape seeds, skins, and tartrates, until that’s separated from the wine by the process of racking.
Sur Lie Aging
When a wine is sur lie aging, you can see layers of fine lees in the wine. There are three separate layers in this barrel image that I took. It demonstrates many layers of lees, just before they’re stirred. Lees have a milky look to them in the barrel.
There are two different types of lees
- There are the grape lees (coming from the fruit)
- Yeast lees, coming from the yeast
Each kind of lees can be used in sur lie aging, and each produces different results. It’s a winemaker’s call what happens in the winemaking process, just as chefs add different ingredients. Winemakers play around with lees, when they age Sur Lie.