Balsamic vinegar is made primarily from grape must, which is the freshly pressed juice of grapes including the skins, seeds, and stems. Traditional balsamic vinegar is made exclusively from sweet white grape varieties, typically Trebbiano or Lambrusco grapes. The grape must is cooked down to concentrate it, then fermented and acidified. This mixture is aged for a long period, usually between 12 to 25 years or more, in a series of wooden barrels made from different types of wood such as oak, chestnut, cherry, juniper, and mulberry, which impart complex flavors to the vinegar
. In the traditional process, the cooked grape must is left to ferment naturally for several weeks before aging. The aging involves transferring the vinegar through progressively smaller barrels each year, a process called "rincalzo," which helps develop its rich, thick, and sweet flavor profile
. This traditional balsamic vinegar is a specialty product from the Modena and Reggio Emilia regions of Italy, where it is strictly regulated. More common commercial balsamic vinegars, such as Balsamic Vinegar of Modena I.G.P., may be made from a mixture of grape must and wine vinegar and aged for a shorter time, sometimes with added caramel or thickeners to mimic the traditional product
. In summary, balsamic vinegar is made from concentrated grape must that is fermented and aged, with traditional versions relying solely on this ingredient and long aging times to achieve their distinctive flavor.
