Sherry - The art of fortification, ageing and quality
Stored in oak barrels, the many varieties of sherry develop their special aromas.
Due to high demand, winegrowers in earlier centuries were happy to sell the wine when it was still very young. However, it did not keep for long and was in danger of tipping over during the months of sea voyages and overland journeys. Alcohol was therefore added to the wine and it was "fortified" to a higher alcohol content so that it would have the necessary storability. This fortification developed into the decisive part of the wine-making art, is critical in determining the eventual taste and aromas of the wine, and is characteristic of the sherry we know and appreciate today.
So-called flor yeasts can form at an alcohol content of 15.5%, which cut off the oxygen supply to the wine. This process is called "biological fermentation" and produces Fino or Manzanilla sherries. Oloroso sherries, on the other hand, ferment with oxidation and have an alcohol content of at least 17%. Stored in oak barrels, the many varieties of sherry develop their special aromas in cellars with ingenious architecture that guarantees perfect climatic conditions in terms of humidity, air circulation and temperature. Sherries can mature for up to 30 years before they are bottled, making them some of the oldest drinkable wines in the world.
The so-called solera process is used to guarantee that the sherry is of consistent quality. In this process, two more barrels each containing younger wines are stacked on top of the bottom barrels, called soleras. If some wine is drawn from the solera barrel, the corresponding quantity is added from the middle barrel and this in turn is replenished from the top barrel.
Moreover, the "spent" sherry casks can be upcycled - they are bought by distilleries in Ireland, Scotland and so on, which use them to mature or finish their (single malt) whiskey.