sábado, 4 de agosto de 2012

The Wine Making of Spanish Sherry


THE WINE MAKING OF SPANISH SHERRY

The harvest begins when the Palomino has reached a must weight of at least n °baume, traditionally on 8 September. It lasts for about a month.

Grapes are loaded into plastic crates and transported to large automated wineries, where they are destalked and pressed. Most bodegas use horizontal plate or pneumatic presses to control the extraction rate, which may not legally exceed 72.5 I/19 gal of juice from 100 kg/220 lb of grapes (16 per cent higher than the extraction rate permitted for cham¬pagne, for instance). Others, especially the cooperatives, use continuous dejuicers which tend to produce coarser wines with more solids and phenolics. Today acid levels are adjusted with the addition of tartaric acid prior to fermentation, and cold stabilization before bottling is usually essential.

After settling or centrifugation, fermentation generally takes place in temperature-controlled, stainless steel tanks, although a few shippers continue to ferment a small proportion of their wine in butt, mainly to impregnate and season new casks of American oak that are to be used for maturation. (New barrels are not valued in Jerez).

The modernization of the sherry industry which began in the 1960s and continued through the 1970s and 1980s has removed much of the mysticism that once surrounded the production of sherry. The modem winemaker can predetermine which of the two initial sherry types (fino and oloroso)each lot of grapes becomes.

The first selection takes place in the vineyard. Wines for the best finos are sourced from older vines growing on the best albariza soils while olorosos are made from grapes grown on the heavier clays. Elegance is crucial to finos, also made from the best free-run juice, which has fewer impurities than the slightly coarser and more astringent juices from the press, which are set aside for olorosos or inferior rayas. particularly coarse olorosos. Wine destined for fino tends to be fermented at a lower temperature than that made for oloroso. Barrel-fermented wine is often too coarse and astringent for the production of fino.

The second selection takes place soon after the end of fermentation. Although many shippers producing table wine endeavour to persuade otherwise, Palomino-based wine is fairly flat and characterless with a natural alcohol content of 11 or 12 %. Depending on the style of the wine, sherry is fortified with grape spirit to between 15 or 15.5 and 22 %. The appearance of flor, the veil of yeast that forms on the surface of the wine and distinguishes fino from other styles of sherry, is determined by the degree of fortification. Growth is inhibited by an alcoholic strength much above 16 %. Wines destined to develop into finos are therefore fortified to 15 or 15.5 %. Olorosos, which mature without flor, are fortified to a higher strength of around 18 %.

The sherry bodegas are teeming with the flor yeast strains. This beneficial film-forming yeast grows naturally on the surface of the wine, although some houses now choose to cultivate their own flor culture. Butts used for fino are only partially filled to around five-sixths of their 600-l to 650-l (160-70-gal) capacity because flor, which both protects the wine from oxidation and changes its character, feeds off oxygen as well as alcohol.

Flor is also extremely sensitive to heat and in the warm summer months it tends to die. In Montilla, for example, flor is reduced to a scum-like film in July and August, while in the cooler Jerez region it grows all the year round. However, there are significant climatic differences within the Jerez region. Flor grows more thickly and evenly in the cooler, more humid coastal towns of Sanlúcar de Barrameda and Puerto de Santa Maria than it does in the bodegas situated in Jerez de la Frontera itself. This accounts for many of the subtle differences in style between Jerez Fino, Puerto Fino, and Manzanilla.

Left to its own devices, flor would feed on the nutrients in the wine and die before having a profound influence on the wine’s character. However, flor is kept alive in casks of fino for six years or more by continually replenishing the butt with younger wine, and replenishing the yeast nutrients. This is the basis of the Solera system, a method of fractional blending which, apart from nurturing flor in fino, also maintains a consistent style for other sherry styles.

A sherry solera comprises a number of groups of butts, each of which is known as a criadera. Wine is withdrawn from the group containing the oldest wine, which is itself called the solera. This is replenished from the butts that form the first criadera, which is in turn replenished by wine from the second criadera, a process known as ‘running the scales’. Simple soleras are fed by three or four criaderas while more complex systems run to as many as 14. The whole system is fed with new wine from the most recent harvest. Up to 33 % of the wine in a solera may be withdrawn in any one year. Fino soleras need to be refreshed the most frequently, and by running the scales at regular intervals (usually two or three times a year) flor may be kept alive for eight to ten years.

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