Balsamic vinegar is an interesting addition to the list of available Italian products.  It was introduced to the American market sometime in the 1970's and has grown in popularity in the culinary circuits.  It is unique, unlike wine vinegar that is made from wine that turns to vinegar, this is an elaborate process that began over 900 years ago.  There are two regions of Italy that produce authentic balsamic vinegar, Modena and Reggio Emilia.  The finished product, that take a full twelve years . . . that's right twelve years,  and bears a consortium seal.  The vinegar itself, has a deep glossy brownish color; it has a complex compound of flavors, somewhat tart, yet sweet as a result of the various wood barrels that are used in the process.  In order to authenticate what you are buying, the bottles are a distinct design (see our photo), and must bear the DOP seal, and of course the words Aceto Balsamico Tradizionale di Modena or di Reggio Emilia on the label. The operative word is "tradizionale". 

The grapes of the region of Modena and Reggio Emilia begin the process; sometimes other varieties besides the grapes of the region known as Lambrusco and Trebbiano. The grapes are first gently squeezed passing through a coarse sieve to remove the flesh, skin and seed of the grapes.  The juice is left to settle before the journey through twelve years begins.  The next step in the process is to cook the juice.  The juice is placed in a large kettle, skimming off any impurities and brought to a temperature between 185 and 195 degrees.  This is just below a boiling point and it continues for 24 and 42 hours.  The varying time verses temperature is to monitor the process, so the sugars do not carmelize.  If that occurs you will never have a true tasting balsamic vinegar, because it will block the first of two fermentation process.  Once the second process begins the alcohol that was created by the yeast becomes an acetic acid.  This gets a little two technical so, let's fast forward the process to what occurs next.  (Sorry chemistry is not my strong suit).  The information I gleened goes on to say the two processes, the yeast and the vinegar bacteria are normally antagonistic to one another but somehow the chemistry allows them to co-exist to  develop the cooked grapes or "mosto cotto". 

Once the juice is removed it is now about half the amount that was started with.  It is transferred into holding tanks for the fermentation process to continue then it is transferred to barrels.  The barrels are a variety of woods, juniper, oak, chestnut, mulberry, ash, cherry or other fruit type woods. The barrels are arranged in size from 100 liters to about 10 liters, each size representing a different  wood. As the process continues the balsamic is moved to another barrel; the tops remain open to allow for evaporation and replacement of what evaporates occurs on a yearly basis.  The open casks actually allow for oxygen to enter and continue to convert the alcohol to vinegar, which also creates a concentration that results in its thick consistency.

Replenishment due to evaporation occurs by taking in order from the smallest to the largest cask.  So, the smallest cask receives replenishment from the cask that is next size, then what is taken from that cask, is replaced by the next size, until you get to the largest cask.  Then the new "mosto cotto" from the kettle is poured into the largest cask, which is repeating the journey once again.

The barrels are stored in attics where there is a fair amount of exposure to drafts and the seasonal variations that account for the process to be completed.  Being a living organism is responds to the temperature fluctuations.  So now you have the story and can appreciate why a ""tradizionale" costs more; is it worth it, you bet it is.