What Are Lees In Wine

As a certified sommelier, I've geeked out over the technique winemakers use to provide an extra sense of luxury on the palate, and it's not from oak. I am talking about lees aging, especially extended lees aging. It's winemaking wizardry that takes everyday wines and turns them into showstoppers. Today, we're diving into what lees aging really means, which bottles love it most, and why winemakers use this technique in the winery.

What Exactly Are Lees, and Why Age on Them?

After fermentation concludes, the yeast has converted the grape sugars into alcohol and carbon dioxide. The exhausted yeast cells die off, settling at the bottom of the barrel or tank alongside small particles of grape skins, seeds, and pulp, and this sediment, known as lees, represents a valuable resource for winemakers.

Lees aging, often called "sur lie" (French for "on lees"), means leaving the wine hanging out with this sediment instead of scooping it out right away. Winemakers might stir it up regularly, a process called bâtonnage, to keep the lees suspended and maximize contact. Now, beware, we're going to get a little geeky over the science involved with lees aging. You see, when lees aging over weeks, months, or even years, the yeast cells undergo autolysis. They break down, releasing polysaccharides (like mannoproteins), amino acids, and antioxidants into the wine. Those mannoproteins act like a natural stabilizer, giving the wine that creamy mouthfeel without heaviness. Ok - science lesson done!

"Lees" also shields the wine from oxidation, keeping it fresh and vibrant. No wonder this old-school trick feels like a superpower; it's been used for centuries, from Burgundy cellars to Champagne houses.

Which Wines Get the Extended Lees Treatment?

Not every wine needs lees aging. It's a technique saved for styles of wine that crave extra depth, for instance, high acid white wines and sparklers, where texture sits front and centre.

Champagne is the poster child. In the traditional method (same as Cava, Crémant, Franciacorta, or South Africa's Cap Classique), secondary fermentation happens in the bottle. Here, the wine sits on those lees for anywhere from 1 to 7+ years. That extended time on lees infuses those iconic biscuit, almond, and autolytic notes.

White still wines shine from lees aging, too. Burgundy's rich Chardonnays often get 6-12 months on lees for that opulent, nutty profile. Muscadet from the Loire gets much of its expression from "sur lie," picking up citrus zest and a saline edge that screams oysters. Galicia's Albariños and some New Zealand Chardonnays do it for similar vibrancy.

Orange wine, made from white grapes fermented with their skins (and often seeds and stems) like a red, already brings a unique tannic structure, amber hue, and bold flavours of tea, dried apricot, and spice. Extended lees aging takes this skin-contact style to another level by leaving the wine on its dead yeast cells post-fermentation for months or more, often with periodic stirring. The lees release mannoproteins and polysaccharides that soften the wine's grippy tannins, enhancing its creamy mouthfeel, and adding savoury, nutty layers.

It is rare to see red wine go through extended lees aging, but you'll find some lighter styles like Beaujolais or experimental Pinot Noirs.

https://www.youtube.com/watch?v=XlIGx-t-LeI

Why Do Winemakers Use Lees Aging in Winemaking?

Winemakers use lees aging because it delivers results. First, flavour - those autolytic compounds bring savoury umami, toasted nuts, brioche, even a touch of smoke.

Texture is the real goal, though. Lees soften harsh acidity, round out edges, and build body, making lean wines feel indulgent. I always say that it is like adding cream without the calories. (Feel free to use that one!)

Practically speaking, it's a multitasker. Lees naturally scavenge oxygen, reducing oxidation risks and letting winemakers cut back on sulphur dioxide, which is a win for cleaner wines. It boosts protein and tartrate stability, meaning fewer fining agents and interventions. For sparklers, it enhances effervescence and aging potential.

It should be said that there is a downside to aging a wine for too long on lees.

A wine left for too long on lees can go funky or reduce fruitiness, so it's all about balance. Also, stirring takes elbow grease, and not every grape thrives (high-acid whites rule here). But when done right, it's transformative.

There you have it. Lees aging demystified!

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