The primary difference between red and white winemaking is that the juice (must) is left in contact with the skins for red wine to extract colour and tannin. The amount of colour will depend on the type of grape used - Syrah, for example, gives dense colour - and the length of time that maceration on the skins is permitted.
On arrival at the winery the grapes are usually de-stemmed, although stems are sometimes used, and put through a crusher to break the skins and release the juice. The entire mass is then placed in the fermenting vessel where a 'cap' of the skins forms. This cap has to be kept submerged, normally by 'pumping over', to extract colour and flavour. Temperature, although controlled is kept higher than for white wine, at around 29 degrees C, again to extract colour and skin contact can be anything from a few days up to a month depending on the style of wine required.
The best wines are then made from the 'free-run' juice with the lesser quality coming from the pressed mass - known as press wine. This latter wine is dark and tannic and is used for blending purposes. Red wine can then spend anything from a few weeks to a few years in either stainless steel or oak where it is racked and fined several times prior to bottling. Some top quality red wines can spend several more years in bottle prior to release e.g. Spanish 'Gran Reservas'.
Whether to mature in oak, ferment in oak, use new oak or old oak, American oak or French oak or no oak at all - the debate continues and will always continue. Many winemakers believe the true varietal characteristics of their grapes are masked by oaking while others swear by the enrichment given to their wines through the use of oak - it's all about perception of style. At the end of the day the market will probably dictate.
