Information about Vinification

chapeau

Chaptalization

charmat

The direct addition of sugar (either cane sugar or beet sugar [sucrose]) is called chaptalization (named for the chemist Chaptal who first introduced the procedure). Because the sugar is converted into alcohol, it does not matter whether it is basically fructose or glucose (the same as in grapes) or sucrose (obtained from sugar beets). The effect is to increase the alcoholic content of the wine, as the sugar is converted into alcohol. 17 g/l of added sugar gives an additional 1% alcohol. The process improves the quality of the wine by increasing the alcohol level, but the improvement is counteracted by the dilution of flavors because of the mass of added sugar. The sugar can in principle be added at any point during fermentation. If added at the beginning, it can increase the temperature of fermentation carried out under non-temperature controlled conditions, which can be a problem. Chaptalization at the end of fermentation is thought to stress the yeasts and lead to production of glycerol, with improved roundness in the wine. It is limited in the European Union to <2% increase in alcohol, but it is generally agreed that >1-1.5% increase creates an unbalanced wine.

Must adjustments
The must is the juice extracted from grapes while it is being fermented to produce wine. Typically adjustments are permitted to the must before or during fermentation that are not permitted for finished wine, although there are some examples of treatments permitted for wine but not for the must. The must can be treated to help fermentation to start. In the E.U., it is permitted to add a nitrogen source (ammonium phosphate or sulfite) or thiamine, both of which are required by the yeasts. Bentonite can be added to remove proteins (including polyphenoloxidase, which helps prevent oxidation). Activated charcoal is permitted to remove colors from white wine. Some of the adjustments that can be made to the must are usually regulated according to the climate. Typically the addition of sugar (chaptalization) or the removal of acidity is allowed in cool climates, whereas acidification is allowed in warm climates. Better results are obtained by adjusting the must than attempting to correct errors in the finished wine. In some jurisdictions, adjustments are allowed only before fermentation. However, it is not always possible to predict precisely the course of fermentation, and sometimes it is necessary (if permitted) to adjust the wine after fermentation. For example, acidity may change in either direction during fermentation, either because of deacidification by yeasts or because they produce malic acid.