Lees Ageing (Sur Lie)
Ageing wine in contact with the dead yeast cells (lees) that remain after fermentation, which adds texture, body, and autolytic flavour complexity (biscuit, toast, bread) to the wine.
In depth
After fermentation, dead yeast cells and yeast fragments (lees) settle at the bottom of the barrel or tank. Instead of racking the wine off these lees immediately, some winemakers leave the wine in contact with them for an extended period — this is "sur lie" ageing.
The lees gradually break down (a process called autolysis), releasing mannoproteins and other compounds into the wine. These compounds add: a creamy, round texture; subtle brioche, toast, and biscuit aromas; greater body; and stability (mannoproteins help protect colour and prevent tartrate crystals).
Lees ageing is used in: white Burgundy (Chardonnay aged on lees in barrel, often with batonnage); Champagne and other traditional method sparkling wines (where the wine sits on the lees in bottle for months or years before disgorgement); and Muscadet (which must be aged "sur lie" over at least one winter to qualify for the label designation).
The longer the lees ageing, the more autolytic character develops. Prestige Champagnes are sometimes aged on the lees for 5–10 years before disgorgement.
Related exam topics
Frequently asked questions
- What flavours does lees ageing add to wine?
- Lees ageing adds yeast autolysis products — primarily brioche, toast, biscuit, and bread-like notes, plus a creamy, rounded texture. The longer the contact, the more pronounced these autolytic characters. Champagne aged on the lees for many years develops complex, toasty complexity that distinguishes it from simpler sparkling wines. White Burgundy aged on lees gains a characteristic richness and weight.
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