In winemaking, what do the terms "fine lees" refer to?

Fine lees refer to the sediment that remains after fermentation, specifically the dead yeast cells and other solids that settle at the bottom of the fermentation vessel. During the winemaking process, when fermentation occurs, yeast cells consume the sugars in the grape must, eventually dying and falling to the bottom. These yeast cells, along with other particles such as grape skins, seeds, and tannins, are collectively referred to as the lees.

Leaving wine in contact with fine lees for a period, a practice known as “sur lie aging,” can contribute positively to the flavor and mouthfeel of the wine. It enhances complexity by imparting additional aromas and flavors, such as nuttiness or creaminess, which can add depth and richness, especially in white wines.

While the other terms mentioned in the choices are relevant in winemaking, they do not accurately describe fine lees. Unripe grapes refer to grapes that have not reached optimal ripeness for winemaking. Yeast added during fermentation consists of live cells actively converting sugars into alcohol and carbon dioxide, differing distinctly from the inert fine lees after fermentation is complete. Fining agents are substances used to clarify wine and are not synonymous with fine lees, which are a natural by-product of fermentation rather than an additive.