Anatomy of a grape, showing the components extracted from each pressing. At crushing white the french defense pdf stage red wine making diverges from white wine making.
To start primary fermentation yeast may be added to the must for red wine or may occur naturally as ambient yeast on the grapes or in the air. Yeast may be added to the juice for white wine. The carbon dioxide is lost to the atmosphere. The press wine is blended with the free run wine at the winemaker’s discretion. The next process in the making of red wine is malo-lactic conversion. The wine must be settled or clarified and adjustments made prior to bottling. Depending on the quality of grape and the target wine style, some of these steps may be combined or omitted to achieve the particular goals of the winemaker.
Variations on the above procedure exist. This can be done by chilling the wine and adding sulphur and other allowable additives to inhibit yeast activity or sterile filtering the wine to remove all yeast and bacteria. Often in these high sugar wines, the fermentation stops naturally as the high concentration of sugar and rising concentration of ethanol retard the yeast activity. Synthetic wines are a novel product that do not use grapes at all and start with water and ethanol and then adds acids, amino acids, sugars, and organic compounds. The quality of the grapes determines the quality of the wine more than any other factor.