What is Sherry Vinegar?
Sherry vinegar is produced from wine made from Palomino Fino grapes, grown in the unique microclimate of the Sherry region. These grapes produce a pale, delicate base wine that is then fermented to create a unique full flavored vinegar. Sherry vinegar is a denomination of origin product that can only be produced in the Jerez region of Spain.
How is Sherry Vinegar Made?
Vinegar is produced through a fermentation process which uses a special bacteria to convert alcohol and oxygen into acetic acid and water. The first step in the process is the conversion of carbohydrates or sugar in the fruit juice into alcohol. For example, grape juice is fermented by yeast into wine or apple juice is fermented into cider. For the best results, the alcohol level should ideally be between 10-13%. The next step is to convert the alcohol into acetic acid and water.
In the old days, Sherry vinegar was formed only by accident, when a cask of new or maturing Sherry was contaminated with acetic acid bacteria. Nowadays, with the advanced sanitary practices followed by virtually all modern wineries and vinegar production facilities, such accidental contamination is a thing of the past. Today’s Sherry vinegar producers intentionally introduce desired strains of bacteria into pre-selected casks of Sherry to initiate the transformation of the Sherry into vinegar.
Once the Sherry has begun to ferment, it will be allowed to mature through a “Solera” system. Maturing sherry vinegar needs lots of oxygen and fresh air, since the bacteria requires oxygen to convert ethyl alcohol into acetic acid. In addition, oxygen affects the sherry vinegar even after the acetic acid has formed, by further oxidizing components in the vinegar, deepening the color and making the vinegar more interesting and complex in flavor and aroma. The bodegas must be well ventilated. They typically have high ceiling and face south or southwest to take advantage of sea breezes.
What is the Solera system?
The Solera and Criadera method is unique to the Jerez region and is a very important component in the maturing process of Sherry vinegar. The system consists of rows of 500-liter oak casks piled up in pyramid fashion, each containing Sherry vinegar of similar characteristics but different ages. The barrels, which were previously used to store sherry wine, have absorbed the aroma of the sherry and release this aroma into the vinegar.
The oldest vinegar is held in the “Solera,” the bottom row of oak barrels. When vinegar is removed from the Solera for bottling, never more than a third of the barrel, it is replaced with somewhat younger vinegar from the first “Criadera” or the row of barrels stored above the Solera. Then, the void in the first Criadera is replenished with still younger vinegar from the second Criadera located one step above and so on. The topmost Criadera is replenished with new vinegar. The older vinegar is said to “teach” the younger vinegar which is blended into it, developing a uniform, harmonious color, fragrance and flavor. The whole process may be shortened or extended depending on the desired age and quality of the final vinegar.