How Traditional Balsamic Vinegar Is Made
Start With High Sugar Content Grapes
Balsamic vinegar is an aged reduction of white sweet grapes that are boiled to a syrup and then aged for 12 years or longer using the solera system. This involves transferring the vinegar along a line of barrels of decreasing size each year. In the case of balsamic vinegar, the barrels are made of different woods.
- As with most vinegar, true aceto balsamico starts out as must (unfermented juice). Unique from other vinegars, local sweet white grapes with a high sugar content—Lambrusco, Trebbiano and often other varietals like Spergola, used in small quantities. The grapes are grown on the hillsides surrounding Modena—are harvested as late as possible, and often left in the sun for further ripening to increase the sugar level.
The harvested grapes. Photo © del Consorzio Tutela del Soave. - The grapes are then crushed and pressed, and the must is allowed to sit until fermentation is about to begin. Thus, unlike other vinegars, balsamic does not come from wine, but from grape juice that has never been allowed to ferment into wine.
- At the very start of fermentation, the must is filtered and poured into large, open copper cauldrons.
- The must is brought to a boil and slowly simmered over a wood fire. It is cooked until the water content is reduced by an average of one-half. This takes from 24 to 30 hours.
- The must is then cooled, allowed to settle and combined with an older balsamic vinegar—or “mother”—that includes various active yeasts and bacteria that assist in turning the juice into acetic acid (vinegar).
