The wine is drawn off the lees (the sediment at the bottom of the fermentation tanks) using filters or a centrifuge. Next, the wine is stabilised to prevent the formation of tartaric acid crystals, a harmless substance which occurs naturally in wine but which must cause more complaints to wine waiters than anything else. To prevent these crystals forming, the wine is cooled to about -5°C and held in this state for several days before its final bottling, labelling and dispatch. The red wine-making method is different from the beginning. In Burgundy, for instance, the stems are often kept on for pressing, while in Bordeaux they are rarely used. During fermentation of red wines, the skins, stems and so on float to the surface of the vats. This ‘cap’ is vulnerable to attack from bacteria which would taint the wine, so in traditional wineries, men are employed with long poles to keep it mixed. In modem wineries, fermenting juice is sucked up and showered over the surface at regular intervals to prevent the cap forming.
After fermentation, most of the wine is run off. There is still a lot of wine trapped in the pulp of stems, etc, and this is known as the ‘marc’. It has to be pressed again to release extra juices which are held separately. The first press from the marc can produce good quality wine, but subsequent pressings are usually destined for distillation.
The wine is ‘fined’ and filtered to extract any remaining solids, and is then piped into barrels or tanks. Most red wine undergoes secondary fermentation during this stage.
As the wine develops, it is up to the wine-maker to decide whether to make varietal wines (only one grape variety allowed) or a blend. If the wine is not to be aged for long periods, it may be pasteurised to sterilise it before bottling. If it is to be aged, it will usually go deep into the vineyard’s cellars and be kept in oak barrels, the size of which varies depending on the country, or even the region. Wine can age in the bottle as well, and many of the world’s finest wines are those which have a combination of both barrel and bottle ageing.
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