• solid waste matter such as bits of grape skin, pips and pulp, that gradually sinks to the bottom of a cask or barrel. Some wines, especially white wines, are stored with this waste matter (called being ‘kept on its lees’) for a period of time to improve the complexity and structure of the wine. If a wine is to be kept on its lees in this way, the winemaker does not need to add as much sulphur to prevent oxidation during the ageing process in the cellar, although this calls for careful winemaking to prevent excess influence on the wine’s taste from the lees. In a sparkling wine the lees consists of dead yeast cells that are removed during disgorgement.