Raise Acidity in Vinegar
By adding alcohol to a fermenting vinegar the final acidity of the fully fermented vinegar will be increased. The final acidity results from the sum of the ACTUAL acidity and the alcohol content of the fermenting vinegar, if no alcohol losses occur due to evaporation (by the use of an air pump) or excessive formation of a mother-of-vinegar (surface processes with nutrient-rich fermentation media).
The alcohol content of the added alcohol must be greater than the desired final acidity after fermentation, therefore suitable alcoholic beverages are (not sulphurated) wine, high-grade mash, fruit brandy, tasteless high proof alcohol, etc. The maximum reachable acidity under conventional conditions is about 11 to 12 %.