(cream of tartar), the acid potassium salt of tartaric acid, a crystalline precipitate that settles with yeast during the alcoholic fermentation of grape must and in the subsequent storage and processing of the wine. Potassium bitartrate is also present in solution in grape juice. It forms a saturated solution in the wine. The precipitation of minute crystals can start in finished, bottled wine owing to mechanical jolts or a drop in temperature. To prevent this, the wine is kept at a temperature close to its freezing point before bottling. Potassium bitartrate is a valuable raw material for making tartaric acid. It is also used in tin electroplating, in dyeing cloth (as a mordant), and in baking bread.
N. S. OKHREMENKO