What is sherry?

Sherry is a fortified white wine from Andalusia in the south of Spain that undergoes a special ageing process. The area is largely located in the triangle of towns between Jerez de la Frontera (from which sherry takes its name), Sanlúcar de Barrameda and El Puerto de Santa María. Sherry comes in varieties from dry to sweet and in different types.

The Palomino grape variety is widely used for sherry production; other varieties are Moscatel(Muscat d'Alexandrie) and Pedro Ximénez. The grapes are regularly fermented into a dry wine, which is then fortified with high-proof brandy(ethanol). The addition of the alcohol already determines the type of sherry. For sweet sherry, the grapes are dried before pressing to concentrate the sugar; the wine is then also residually sweet after fermentation.

Sherry can be reductive (without the influence of oxygen) or oxidative (with the influence of oxygen). The cellar master decides on this on the basis of the base wines. Reductive types are Fino, Amontillado and Manzanilla, the oxidative type is called Oloroso.

For a reductive sherry, the base wine is fortified after fermentation to about 15.5 percent alcohol by volume, for oloroso sherry to about 17 percent by volume. The fortified wines are then matured in wooden barrels, which are only filled to about 85 per cent (i.e. not full to the brim) and are not sealed airtight. In this way, a yeast flor can form on the liquid of the reductive types: a special yeast layer that protects the sherry from the influence of oxygen during the maturation process. The air in the barrel is initially necessary for the growth of the flor yeast and, after it has "blossomed", it is precisely the flor that prevents it from reacting with the wine; the flor yeast cells surround themselves with a wax layer that allows them to rise in the liquid and forms the oxygen barrier on the surface. In the case of strong oloroso sherry, the alcohol content is too high for the yeast flor to form; this type therefore develops oxidatively, it is dark in colour and nutty in aroma.

Traditionally, a sherry is matured in the solera process. The principle is that the barrels are stacked on top of each other. The row of barrels at the bottom is called the "solera", all the barrels above it form the "criadera". Sherry that is ready for bottling is only taken from the bottom row of casks, with each cask being emptied by a maximum of one third. The quantity removed is topped up from the cask above, a process that continues through all the criadera stages. Finally, the top barrel is filled with the very young wine. The solera process continuously blends the vintages so that the sherry takes on a uniform, harmonious taste. In addition, the flor yeast always receives new nourishment so that it does not die off.

In this way, sherry matures for at least three years, with high-quality examples maturing five times as long or more. The most important types of sherry are:

• Fino (classic, as described, reductively matured sherry with 15-18% by volume)
• Manzanilla (fino sherry with 15-19% by volume from the area of Sanlúcar de Barrameda, where the flor yeast layer is particularly stable due to the climate )
• Amontillado (original Fino sherry with 16-22 vol.%, which matures oxidatively due to the death of the flor yeast layer at the end; the death occurs either due to age after 10 to 15 years or deliberately by adding alcohol again)
• Palo cortado (original Fino or Amontillado sherry with 18-22% by volume, which is produced when the flor yeast suddenly dies, so that further ageing is unintentionally oxidative)
• Oloroso (sherry aged oxidatively as described with 18-22% by volume)
• Medium(semi-dry sherry with 45-115 g/l residual sugar and 15-22% by volume, made from young Amontillado sherries)
• Cream (sweet sherry with 115-145 g/l residual sugar and 16-18 vol.-%, which is produced by blending Oloroso sherry and sweet wine )
• Pedro Ximénez (sweet sherry made from sun-dried Pedro Ximénez grapes with 15-22 vol.%, which is considered a dry berry selection among the sherries)