Red Wine Making

The old way was to tread the grapes, the modern way is to crush and then destem them with mechanical crusher-destemmers. The aim of crushing is to split the skins and release the juice, enabling yeast activity and fermentation to begin. Destemming is not always necessary and bunches may be crushed whole, but stems and stalks are usually removed if the winemaker wishes to avoid high tannins levels in the wine.

Fermentation vats were traditionally made of oak. Many still are, but stainless steel has the advantages of being easier to cool and easier to clean. High uncontrolled fermentation temperatures burn out the fruit flavours in the wine but can also promote greater colour extraction from grape skins, so a good temperature balance is essential. The length of maceration, (the period during which the juice is left in the vat in contact with the grape skins), depends on the depth of colour and tannin required in the wine. Not so long ago workers would get into the vat to break up and submerge the cap of skins. Carbonic maceration is an alternative fermentation process in which the fruit is allowed to ferment spontaneously under a protective layer of CO². The weight of the grapes is sufficient to crush the fruit and release the juice, known as free-run, without mechanical pressure. The resulting wines tend to be softer and less astringent than those fermented in the traditional way, so this method is well suited to grapes which normally give hard, acidic wines. Wines made by carbonic maceration are usually for drinking young and do not respond well to ageing.

Pressing the grape mass or pomace, occurs after the free-run wine has been removed from the fermentation vat. This process is not as important for red wines as it is for white and in fact is not always carried out at all. ‘Press wine’ is high in tannin and colouring pigments. At the discretion of the winemaker a percentage of it may be blended with the free-run wine to add tannins, character and longevity.

This process is almost always encouraged in red winemaking. It is a secondary fermentation in which malic acid is converted into lactic acid and CO². It softens the acidity of the wine and once complete, adds to its complexity and stability. In many European cellars the wines will mature for six months before the malolactic fermentation commences.

High quality red wines today are almost always matured in oak. Oak contributes vanilla and wood tannin flavours. For how long the winemaker ages the wine in a barrel is one of the crucial decisions, arrived at, by regular tasting.

The wine is racked every few months by transferring it to a clean sterile barrel, gently aerating it and leaving any sediment in the bottom of the old barrel. The object of fining is to clarify the wine. The fining agent (usually egg white or bentonite clay) is poured onto the surface. As it sinks through the wine it carries any solids to the bottom of the vat. The final option before bottling is whether or not to filter. Passing the wine through a fine filter guarantees (or should guarantee) its stability and ‘brightness’ even under fairly adverse conditions. But some winemakers believe it strips the wine of its character.

Before bottling the wine should be completely stable. It remains vulnerable to oxidation and contamination until the cork goes in. Mechanical bottling lines account for 95% of modern bottling. It is important to fill the bottles to exactly the right level to allow adequate room for the cork.