The juice is now divided in two: free-run, or vin de goutte, and press wine or vin de presse. The free-run wine and the press wine are then pumped into separate vats or casks. These two wines will undergo, almost always, their malolactic fermentation separately. The malolactic fermentation is a second biochemical process that converts the hard malic acid into two parts lactic acid and one part carbonic gas. To ensure that the malolactic fermentation can take place it is essential that special 'lactic' bacteria are present. Almost all red wines undergo this second malolactic fermentation. The red wine will become softer and fuller. During this fermentation the red wine will also stabilize and it will add complexity to its character. For white wines the malolactic fermentation is used to make them fuller, fatter and more complex. It may be avoided for lighter, crisper white wines and certain styles of sparkling wine. The choice of using vats or casks for the fermentation is essential. Stainless steel vats have the capacity to produce the freshest wines with the purest varietal character. An oak barrel allows acces to the air, which encourages a faster rate of oxidation. Vanillin is extracted from the oak by oxidation. This oaky character can take a smokey complexity if the wine is fermented in the barrels. The oak also softens the tannins of tannic red wines and gives wood tannins to low tannin red wine. After fermentation the wines can maturate in oak to add even more complexity. Whether or not it is to be aged in wood, the wine needs regular racking. Racking means draining the clear wine off its lees, or sediment, into another vat or barrel. This is usually done several times during the maturation period in vat or barrel. After maturation the wine still contains suspended matter that may cause cloudiness in the bottle. To be clarified it undergoes a fining that is sometimes followed by a light filtration before bottling.
	The Process The grapes arrive at the cellar after they have been picked. Some winemakers destem before crushing. Others prefer to retain some of the stems to help with juice drainage. The stems are removed to avoid a high tannin content in the wine. The crusher splits the berries to liberate the juice. Directly after crushing the first cooling takes place in a series of pipes. In such a way as to get the longest length of piping possible into a relative small space. The pipe has a narrower pipe on the inside and it is through this that the must is pumped. In the outer pipe a cold solution is passed in the opposite direction. This reduces the temperature of the must. The crushed grapes are pumped to the fermentation tank. Cooling is an important process in modern winemaking. It can start with cooling the must. Also during fermentation the cooling is important to retain freshness (mainly for white wines). And finally to keep the finished wine fresh in the tanks. The biochemical process that transforms fresh grape juice into wine is called fermentation. Ripe grapes contain sugar which can, under the influence of yeasts, be converted into alcohol and carbon dioxide First or alcoholic fermentation: C6H12C6 > C2H5OH + 2 CO2 sugar   alcohol   carbon dioxide All red wines will start off their fermentation in vats. This is because they must be fermented with a cap of grapeskins. During fermentation the juice is pumped over the cap or punched down once or twice a day, to keep the juice in contact with the grapeskins. Since alcohol is a good solvent this ensures the extraction of colour, tannins and flavour from the skins. White wines are fermented without the skins in vats or casks. Sometimes after a period of maceration to extract the aromatics that are stored in the skin. Rosé is the result of applying this maceration to dark-skinned grapes. Some rosé wines made by this method are virtually by-products of red-wine production. Under certain circumstances that lack the appropriate possibilities for deep red wine, some free run juice might be run off in order to produce rosé, and so concentrate the colour of the red wine. For white wines the juice is pressed out of the grapes before fermentation. For red wines however, the idea is to extract as much usable wine possible from the solids left in the fermentation vat after the free-run wine has been run off. The stronger the pressure the more coarse the wine or juice will be. This is why pressers are designed to press ever gentler.