Sur Lie

Definition - What does Sur Lie mean?

Sur Lie is the winemaking process of aging wine “on the lees”. Lees are the dead yeast cells and/or grape particles that drop when a wine is fermenting. When a wine is aged sur lie, that means the lees are left in the wine during aging. This keeps the wine in contact with the dead yeast cells, adding flavors, aromas, depth and complexity.

Wines made this way are not racked or filtered during the aging process. The winemaker will state on the label “sur lie”, to indicate that this is how the wine was made. The sur lie process originated in Burgundy with Chardonnay. Now popular around the world with numerous white wines and, on rare occasions, with red wines, the sur lie process is still most commonly applied to Chardonnay.

WineFrog explains Sur Lie

As the wine ages, the lees release new elements into the wine that change the flavor, aroma, structure and overall composition. Each grape variety is affected differently, though in general:

  • Chardonnay – toasty, nutty, hazelnut notes, additional depth and complexity on the finish
  • Muscadet – creamy, yeasty flavors and a touch of carbon dioxide (slightly fizzy sensation)
  • Champagne – bready, toasty notes

There are three main reasons why a winemaker would choose to age sur lie:

  1. Reduce oak tannins – lees release proteins that bond with oak tannins, softening the harsh effects of tannins.
  2. Create a specific flavor profile – aging sur lie adds toast, nuts, cream and yeast like flavors to the final product, creating a richer, more complex flavor profile.
  3. Protect against oxidation: the layer of lees at the bottom absorbs oxygen and protects the wine.

Yeast lees release peptides, amino acids, polysaccharides and nucleotides. Peptides change the flavor, aroma, sweetness and nutrients in a wine; amino acids and nucleotides change the flavor, aroma and nutrients; and polysaccharides enhance the stability and mouth-feel of a wine. Grape lees add depth and complexity of flavor and also protect against oxidation. Sur lie is usually done using yeast lees rather than grape lees.

The decomposition of yeast lees is manageable and adds complexity and flavor; while the composition of grape lees, if done incorrectly, could ruin a wine, reducing aromas, oxidizing the wine, contaminating the wine with microbes, inhibiting malolactic fermentation or adding hydrogen sulfide to the wine. The process is as follows: In the end stage of fermentation, the winemaker prepares for sur lie aging. The wine “juice” is left in the vessel with the sediment (usually the wine is filtered of sediment at this stage). As it ages, the wine is stirred (a process called bâtonnage) to ensure the yeast doesn’t create hydrogen sulfide; in the case of bottle aging, the wine bottle is turned. When the wine is ready to be bottled and/or sold, the lees are removed and the wine bottled; in the case of bottle aging, the wine is disgorged.

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