The future Holy Roman Emperor, King Henry III, requested Marquis Bonifacio of Canossa to craft a high quality vinegar in his castle.

[citation needed] In the second half of the 19th century, the provinces of Emilia joined the newly formed Kingdom of Italy, and balsamic vinegar of Modena was promoted at national and international exhibitions.

[citation needed] With the birth of the Italian State in 1860, the awakening of the markets gradually aroused more interest in balsamic vinegar, and considerable historical and bibliographical research was carried out on this product.

At the end of the 19th century, the balsamic vinegar of Modena began to appear at exhibitions, creating great interest locally and internationally.

[citation needed] From a regulatory point of view, the first ministerial authorization to produce "balsamic vinegar of Modena" dates back to 1933.

The resulting thick syrup, called mosto cotto in Italian, is subsequently aged for a minimum of 12 years in a battery of several barrels of successively smaller sizes.

True balsamic vinegar is rich, glossy, deep brown, and has a complex flavour that balances the natural sweet and sour elements of the cooked grape juice with hints of wood from the casks.

[10] PGI status requires a minimum ageing period of two months, not necessarily in wooden barrels, rising to three years when labelled as invecchiato ('aged').

During this period, a portion evaporates: it is said that this is the "angels' share", a term also used in the production of bourbon whiskey, Scotch whisky, wine, and other alcoholic beverages.