Sediment

sediment, the solid material which settles to the bottom of any wine container, whether it be a bottle or a vat, tank, cask, or barrel. This sediment is a very heterogeneous mixture which in winemaking consists mainly of dead yeast cells (the gross lees), the insoluble fragments of grape pulp and skin, and the seeds that settle out of new wine. At subsequent stages it consists of tartrates and, from red wines, phenolic polymers, as well as any insoluble materials added to assist clarification or to facilitate filtration.