A recent story in the vinegar world of Italy is the effect of extended record high temperatures on traditional balsamic vinegar makers in Modena and Reggio Emilia. In particular, the ‘il caldo africano’, a heavy, hot wind that blows into Italy from North Africa, has set record high temperatures for weeks of July and August. This is not as much a concern for industrial vinegar makers, with large air conditioned factories and rapid fermentation, but it is a huge issue for the traditional balsamic makers who still make balsamic vinegar in acetaia or cellars where the barrels of the batteria are used for aging.
The typical balsamic aging process in the traditional style takes at least twelve years and is best carried out between 15 to 20 degrees C (or 60 – 70 degrees F). This temperature allows all the complex reactions to take place that ages balsamic, increases its density, and enhances its flavor. Under current continuous 30+ degrees C (high 80s and low 90s F) conditions, the additional alcoholic fermenation and simpler chemicalreactions of balsamic aging occur more rapidly while the complex, flavor and texture enhancing reactions, which rely on microbes that prefer lower temperatures, do not occur to the same extent. Also, the glucose in the grape must can crystallize and sink to the bottom removing the sweetness and ruining the texture. This means that most traditional acetaia which rely on architecture and insulation to maintain temperature, are threatened with a possibility of reduced quality in their current batches which have been aging for years.
Balsamic fermentation is seasonal and usually a really hot summer or really cold winter can slow it. The problem, as in the last few years, has been hot summers and cold winters that make almost half the year inaccessible for proper fermentation and aging.
The local balsamic vinegar consortium is issuing advice of moistening the outside of barrels with rags dipped in a mixture of water and vinegar to prevent excess evaporation and temperatures in the barrels.