It's easy to make wine. In fact, wine will quite happily make itself with a bit of help. All you do is allow crushed grapes and natural yeasts to convert the sugar into alcohol and hey presto! You've got wine.
The trouble is it probably won't be very pleasant to drink because making good wine is the really hard part. In particular, the winemaker needs to make the right choices at the correct time to achieve the precise outcome. One wrong step often spells disaster.
These days there are lots of great winemakers turning out great wines.
White
First the grapes are harvested and then machine crushed to release their pulp and juice. This makes them easier to press. Next, the crushed grapes are cooled to prevent fermentation from starting too soon.
The grapes are loaded up and pressing begins; the gentler the pressing, the better the quality of the resultant must (unfermented grape juice). The pressed juice is settled in a vat by allowing any remaining skin, pips or stems to fall to the bottom.
The clean wine must is racked (transferred) into separate vats ready for fermentation. The wine is fermented in oak casks or in temperature-controlled tanks. Natural or cultured yeasts are used to begin fermentation, converting the natural grape sugar into alcohol. The length and temperature of the fermentation will affect the style of the wine.
Malolactic fermentation is either encouraged or prevented as required. This second fermentation converts harsher malic acid into softer lactic acid, and can add greater complexity to a wine.
For early drinking whites, wine is racked off its lees and then clarified by filtering, centrifuging or fining to remove the lees (unwanted yeasts, proteins and particles). This helps stabilise the wine. Cold stabilisation precipitates out any tartrate crystals. The wine is then bottled in sterile conditions and may be flash pasteurised or 'hot-bottled' to ensure lasting stability.
More expensive, full-bodied whites are matured on their lees in oak barrels for up to two years after fermentation. During this time, the lees may be stirred to accentuate flavour; the wine may be racked (transferred to clean, sterile barrels) at least once; and it may then be fined and filtered depending on the winemaker's preference. Finally it is bottled in sterile conditions.
Red
The grapes are harvested and then machine-crushed to release juice. They can be de-stemmed at the same time, but if the Beaujolais technique of carbonic maceration is used, the bunches remain whole. Carbonic maceration is an alternative fermentation technique where fruit ferments under a protective layer of carbon dioxide to produce softer, less tannic wines such as Beaujolais Nouveau.
The pomace (grape mass) is transferred to fermentation vats and is encouraged to ferment using natural or cultured yeasts. The temperature and length of fermentation will affect the style of the wine. Some winemakers precede fermentation with a period of cold maceration (soaking) to extract colour and tannin from the skins. Others macerate after fermentation.
After fermentation is complete, the pomace is pressed to extract the wine. Malolactic fermentation (a second fermentation in which the harsh malic acid is converted to softer lactic acid) is often carried out to soften the wine's acidity and add complexity. If the wine is to be blended, this process may take place at this point. The wine is also analysed and checked before maturation.
The wines are transferred to oak barrels or tanks for maturation. With oak barrels, wine is regularly racked from sediment by transferring it to clean, sterile barrels. Maturation in oak barrels can take over two years.
Once the wine has matured, it can then be fined to clarify it. This involves adding a fining agent such as egg white or bentonite which binds itself to impurities, depositing them at the bottom of the vat. The wine can also be filtered as an additional stabilisation process, although some winemakers believe this strips it of character.
