From The Food Encyclopedia by Jacques Rolland and Carol Sherman
A distinctive type of vinegar, once considered so valuable that it was included in the dowries of young ladies of nobility and specifically mentioned in wills. It has been made for hundreds of years from the cooked and concentrated must of white grapes in the area around Modena and Reggio Emilia in Italy. The juice of local Trebbiano grapes is aged in a succession of 12 kegs, each decreasing in size, made of different aromatic woods, such as juniper, mulberry, chestnut and red oak. This process can take as long as 50 years, giving the vinegar a somewhat syrupy texture and a rich, deep-mahogany color. Stored in a light and airy attic, subject to the heat of the summer and the cold of the winter, it will age and thicken to the consistency of molasses. Bona fide balsamic vinegar (aceto balsamico tradizionale di Modena) is strictly controlled by law and must have been aged in wood for at least 12 years. Vinegar aged 25 years or more is called stravecchio. The name balsamic means "balm-like", reflecting its digestive character. Indeed, the best has a flavor so smooth and sweet that it can be drunk on its own as a digestivo (after-dinner drink). See also vinegar.
