Wine Vinegar

Wine, during its life in a barrel, must be regularly replenished from smaller containers—bottles or barrels—of the same wine to compensate for loss by evaporation, because if the wine is left in contact with air, an insidious culture in the form of a frail, white powdery veil will develop on the surface, eventually transforming the entire body of wine into vinegar. The same detested fleur blanche, for the fabrication of a good vinegar, must be pampered, kept at room temperature (60°F.–75°F.), a body of air always in contact with the surface, which should not otherwise be disturbed; the mold lives only in contact with air and, if submerged, is transformed into a heavy viscous matter called colloquially mere de vinaigre (“mother of vinegar”), which settles, harmless but inactive, to the bottom of the container.