In the wine world, we routinely hear of how long famous Champagne, White Burgundy, or even value Muscadet wines were aging "Sur Lie" (on the lees). But what does this mean exactly? What are lees and what wines benefit from their presence?
Let's take a look!
What are Wine Lees?
Lees are the sediment that looks like thick sludge collecting naturally at the bottom of a vessel throughout or post-fermentation. It consists mostly of dead yeast cells over time, but towards the beginning of the winemaking journey, they can include grape pulp, skins, stems, seeds, tartrates, and other heavier fragments in the wine. Following primary fermentation, the yeast may have completed their job converting sugar to ethanol and carbon dioxide, but will continue helping out in other ways after they’re dead! They even provide nutrients for the bacteria in charge of the following malolactic fermentation.
What does aging on the lees do for wine?
Aging on the lees will benefit the wine in a variety of ways throughout the winemaking process from oxygen protection, beneficial nutrients for the lactic acid bacteria during malolactic fermentation, rounding out the mouthfeel of the wine giving more body and richness, and most notably the yeasty, bready flavors that you may find familiar in other fermented products. Winemakers in the Veneto region will often even add lees from their premium red wine to other wines for added complexity and flavor!
Gross Lees vs Fine Lees
You may read tasting notes or the back of a wine label mentioning the wine was aged particularly on the fine lees. Fine lees are of higher quality that don’t settle immediately to the bottom. Gross lees or "Coarse” lees typically are the heaviest solids in a wine that will settle to the bottom the quickest. Gross lees may include other material in the wine that could potentially carry sulfurous compounds from the vineyard or spoilage organisms. Winemakers will typically move wine off the gross lees, sometimes as soon as 24 hours, once it's had time to settle post grape pressing.
The fine lees will take longer to settle to the bottom of the vessel and can impart mannoproteins broken off from the dead yeast cell walls. This gives the wine a creamier texture, the longer they sit together. Most wineries will “rack” or move the wine off the lees for various reasons throughout the aging process. These reasons could be to give the wine oxygen, clarify the wine naturally, or if they believe the wine has gained enough of the lees' flavor or texture.
What is Bâtonnage and why do we do it?
"Bâtonnage" is a French term for stirring the lees, a process routinely used in the Chardonnays of White Burgundy. It is not always used as heavily in lees aging elsewhere as it can have it's advantages and disadvantages. Winemakers will insert a long narrow stainless steel tool through the bunghole of the barrel that stirs the lees resting on the bottom of the barrel into the solution to enhance texture.
Bâtonnage is also very helpful because the lees absorb oxygen first through the porous barrel leaving minimal amounts for the clear wine above. This can create a "reductive" environment of hydrogen sulfide giving off a potential rotten egg aroma. Stirring the lees will introduce some of the oxygen and keep the wine smelling fresh. Stirring can be done weekly, bi-weekly, or monthly, but too much can impart a pronounced yeasty flavor along with introducing too much oxygen masking the vulnerable fruit aromas.
Which wines age on the lees?
Sparkling wines such as Champagne, or traditional method sparkling wine, will undergo long lees aging in the bottle. The length of time required for many of these sparkling wines to age on their lees can be years. That, coupled with the ratio of lees to wine in the bottle, creates an ultra autolytic environment making the bready, brioche character you recognize in Champagne, much more intense.
Many white wines are aged on their lees in the barrel, but the most noteworthy include barrel-fermented/aged Chardonnay and Muscadet (Melon de Bourgogne). It's also common to find Albariño, Grüner Veltliner, Pinot Gris, and Chenin Blanc with lees aging.
In the end, the lees are another tool in a winemaker's toolbox for flavor, texture, and oxygen protection. It is all about balance to make the most expressive wine you can make. Now that you know what to expect next time you see a wine with some of that aged lees character, give one of our barrel-fermented whites a try! Cheers!
Author Bio: Brian is a graduate of the Institute for Enology and Viticulture in Walla Walla, WA, and a Certified Specialist of Wine via the Society of Wine Educators, Brian will be working his 3rd harvest this fall in a new region, the Willamette Valley. He feels there is always something new to learn about when it comes to the world of wine and that's what keeps it exciting. He hopes the industry will carry on being more inclusive and less pretentious giving everyone the opportunity to enjoy the world's greatest beverage.