1- Reception
2- Separation of the must
3- Stemming
4- Pressing
5- Fermentation
6- Racking and clarifying
7- Bottling
c) Fermentation
The must, now free of suspended solids, is fermented at a temperature of between 18º and 22º C. This procedure allows the doubling of the sugar content in the alcohol and the emission of carbon dioxide to occur slowly and gradually. The goal is to preserve the true aromas of the wine and thus obtain the best quality possible in the final product.
Alcoholic fermentation takes between 10 and 15 days. Fermentation is complete when the wine contains between one or two grams of sugar per litre, the point at which it is totally dry (that is, it has a very low sugar content). However, today very dry white wines are difficult to find, since a certain proportion of residual sugars is usually maintained to obtain a stronger bouquet.
The wines from wetter areas, which have a high proportion of the malic acid lacking in wines from warmer areas, undergo a second fermentation called malolactic or maloalcoholic fermentation. The action of bacteria (malolactic) or yeast (malolcoholic) causes the malic acid to be converted into lactic acid or alcohol, which may occur at the same time as alcoholic fermentation or later.
d) Racking and Clarifying
After fermentation, between the second fortnight of November and the beginning of January, the wine undergoes two or three rackings to remove the solids which appear during fermentation. However, after racking there are usually some solid elements in suspension that could decompose, which would affect the appearance of the wine and give it unpleasant aromas and flavours.
To eliminate these particles, the wine is subjected to a clarifying process that lasts approximately ten days. This process consists of introducing substances that drag the solid particles downwards and deposit them at the bottom of the tank. The next stage is filtration: the wine is passed through substances that retain the particles contained in the wine. Various methods, ranging from earth and screen filters to the most modern techniques using amicrobic sterilizers, are used in this process.
Finally, the wines are selected and separated by qualities so that, through careful blending, each one will be bottled by type according to the final product sought.
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