Raise Final Acidity
Continue the vinegar fermentation by adding alcohol.
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 %.
1.92 liters of alcohol with 12.5 % ABV
6.92 liters of mixture with 2.53 % acidity and 3.97 % ABV,
is equivalent to 6.5 % acidity in fully fermented vinegar.
Losses due to alcohol evaporation or formation of a mother-of-vinegar during fermentation were not taken into account.
ABV: Alcohol By Volume (alc./vol.)