The Physical and Chemical Stability of Wine

Abstract

The major physical instability in bottled wines continues to be the precipitation of the tartaric salts, potassium bitartrate, and calcium tartrate. Prevention of this precipitation in bottled wines is desirable because consumers find it objectionable and an indication of poor quality control. Precipitation of these salts can be due to one or more reasons, such as the incomplete stabilization in the cellar, the use of a nonrepresentative sample for the stability test, the use of an inappropriate stability test, the removal of colloidal materials at the point of final filtration that have previously inhibited the precipitation and natural chemical changes, especially the polymerization of phenolic pigments. The initial instability is caused by supersaturated levels in juices that are augmented by the decrease in solubility due to ethanol and the low temperatures used for wine storage.