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Wine
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Production process of wine
The production process of wine may differ by type of wine and even by season. The production process mentioned below is a standard production process with some frequent occurring extra intermediate steps. Each extra step or change of a parameter results in another type of wine. Besides that, the type of grapes is of course of major influence. Generally, more extra steps are executed in the production process of red wine.Cleaning
After the grapes have been picked they are cleaned. Affected grapes, unripe grapes but also twigs and sand are removed. Subsequently, in most cases the stalks are removed. With some red wines the stalks are left on the grapes to give an extra flavor (by its tannin) to the wine.Pretreatment
Sometimes blue grapes are given a whole bunch fermentation (also macéron carbonique). This fermentation makes sure that early fruity aromas are formed. The whole bunch fermentation happens in the absence of oxygen. This is done by letting the grapes ferment in a closed tank with carbonic dioxide. This fermentation is an intracellular fermentation, without adding culture to it.After the undesirable parts are removed and after a possible intracellular fermentation the grapes are bruised and pressed. When white wine needs to be obtained the skins are removed afterwards. For red wine the skins are removed in a later phase so that they can still give color and tannin to the juice.
Chaptalisation or acidification?
The grape juice can be chaptalised or acidified. Chaptalisation means that sugar is added, which is done when the grapes do not contain much sugar of themselves. Each 18 grams of sugar in a liter of must (grape juice with the possible skins) results in 1% alcohol. In the north of Europe en in cold areas it is normal and allowed to add sugar. In the south of Europe it is prohibited, although it is allowed to add concentrated grape juice, which also results in an increase in sugar level and therefore in the alcohol level.Acidification is the opposite of chaptalisation and is done when the must does not contain much acid. In most cases tartaric acid is added because this is least obtrusive. Apple acid or citrus acid are also used sometimes. Acidification can be done before or after the fermentation, but doing it before the fermentation gives the best mixture in the must.
Removing the skins
For a mild wine the level of tannin should not be too high. To obtain this the skins can be removed. The disadvantage, however, is that the wine has no or almost no red color. The solution is a cold soak (maceration) before the fermentation. By a cold soak of 24 hours the color of the skin is absorbed, but not much tannin is.Fermentation
After this the fermentation can be started. During the fermentation the sugars are converted into alcohol and aromatic substances. The fermentation has to happen at a constant temperature, for white wine the temperature should be between 12 and 20ºC, for red wine between 35 and 40ºC. When fermentation happens at a too high temperature the wine looses its aroma, freshness and character. With red wine it is important that the skins and the possible stalks that surface (called the cap) are stirred in the must to advance the transfer of color and tannin. An important decision in the fermentation process is the choice for the original fermentation culture on the grapes, which may differ each season and may consists of several cultures, or the choice for adding one or more pure cultures. With this last choice the process is more constant and similar aromas are produced. Each culture advances certain aromas and puts others to the background.Maceration
Sometimes a maceration is executed with a red wine. This is a after soak in which the cap remains on the must for a deep color and more tannin in the wine. After this possible maceration the cap is removed.Subsequently it is possible to execute a must concentration. This is done for Bordeaux wines, but in other regions it is not much used. The concentrating of the must by means of evaporation under vacuum or by means of a reversed osmosis gives the wine a richer flavor. The effects of must concentration on the ripening aromas (in the long term) is for the time being unknown.