Definitions for "Tartrate Crystals"
Potassium bitartrate is a salt of tartaric acid known by the common household name of "cream of tartar". Grape juice contains considerable tartaric acid, and this acid becomes concentrated in the juice during fermentation. The result is the precipitation of tartrate crystals on the sides of the barrel. The crystals do no harm, but if not removed may end up in the wine bottle. They are easily removed by filtering. Their growth in the fermentation barrel can also be inhibited by using ion-exchange resins in the barrel to replace potassium ions in solution with sodium ions. Because sodium bitartrate is more soluble than the potassium form, this helps prevent crystallization.
Tartaric acid, the primary acid in grapes, forms tiny crystals when chilled. These crystals adhere to the cork or form sediment in the bottle, and are not considered a defect.
Harmless crytstals that are sometimes deposited in bottles of white wine that have not been cold stabilised.