Acetaia La Secchia, a Balsamic vinegar producer from Modena, explains the refilling procedure, transforming cooked grape must and wine vinegar into Balsamic vinegar.
This is a line up from 1988, so approximately 30 years old
We have six different types of wood, usually we use the softer wood at the beginning of the line
Like for example Mulberry, a very soft wood that allows an excellent oxygenation of the vinegar.
The harder types of wood are towards the end of the line, such as oak or chestnut.
During the first year, we add the cooked must of typical grapes from Modena
So, the three Lambrusco varieties, two Trebbiano ones and Ancellotta in all six barrels
Therefore the same amount of cooked must is in all the barrels.
After a year, we notice that every barrel has lost around 10% - 12% of the cooked must that we put in the barrels
At which point, the must missing from the smallest barrel is topped off by taking it from the previous barrel
This type of procedure is applied to all the barrels up until the largest one.
The largest barrel, that will need 20 - 25 liters of cooked must, is topped of by the must of the new vintage.
This procedure ensures that the contact of the vinegar with the wood, and the cooked must with the wood
and with the oxygen, produces acetobacter, that afterwards transforms sugar into alcohol
and the alcohol into acetic acid, and that slowly creates the acetic and organoleptic depth
that afterwards, after many years of aging, makes the vinegar particularly refined.