Chemical phenomenon

The fermentation of a wine.

This process consists of the transformation of the sugars present in the grapes into alcohol. This transformation is carried out thanks to the yeasts that are scattered throughout the environment. From here, and mostly ethyl alcohol is obtained, although carbon dioxide is also generated and it is this that causes the wine to appear to boil during this process.

During fermentation, different substances such as glycerol, succinic acid, acetic acid, higher alcohols, and many more substances are released that will influence the final quality of the wine. Throughout this natural process, more than thirty chemical reactions occur

It is not surprising that the first to explain it scientifically was Pasteur.

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There are different chemical signals that participate directly in alcoholic fermentation, including the availability of nutrients such as fermentable sugars, assimilable nitrogen, oxygen, vitamins, minerals, ergosterol and the presence of inhibitory substances such as ethanol, acetic acid, fatty acids, etc.

The Oxigen; Its presence is essential and favors the growth of yeasts. However, without it, fermentation proceeds better. Knowing the exact point of oxygen during fermentation is essential to obtain a good red wine.

For centuries, a work in the cellar called the pumping-over process. This process consists of pumping the wine that is fermenting in the lower part to the top of the vats

Acidity; It is made up of different acids, in the free or compound state, some derived from grapes (malic, tartaric and citric) and others from different fermentation processes (succinic, acetic and lactic). Some contribute to the transformation, disappearance or appearance of the different acids.

High acidity can cause different effects, such as preventing yeasts from developing and preventing the growth of undesirable bacteria.

We highlight tartaric acid, which is the specific acid of grapes and wine. The acidity of the wine depends a lot on the richness in Tartaric Acid as it is the greatest liberator of H+ ions, and represents 25 to 30% of the total wine and is the most resistant to decomposition by bacteria, which transform it into Lactic and Acetic Acid.

The increase in alcohol and the low temperatures precipitate it in the form of crystals of Potassium Bitartrate and neutral Calcium Tartrate, for which the wine contains two to three times less Tartaric Acid than the must from which it comes.

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"Tartaric acid or" tartaric acid "is a polyfunctional organic compound, whose group is carboxyl (carboxylic acid).

Its formula is: HOOC-CHOH-CHOH-COOH, with molecular formula C4H6O6.

Appointed by the IUPAC as 2,3-dihydroxybutanedioic acid.

Its molecular weight is 150 g/mol. "

Nutritious substances; They are vitamins, minerals and nitrogen that are usually found in the must.

As fermentation progresses, the sugar content in the wine decreases and the presence of alcohol increases. In this way, the yeasts die little by little due to lack of food and the process stops, obtaining a dry wine, without sugar. If you want to create sweeter wines, you must stop the fermentation earlier, either by reducing the temperature, or by adding wine alcohol or adding sulphites.

The function provided by the alcohol that has been generated during fermentation is very important, as it favors tartaric precipitation, which is a process that eliminates the derivatives of tartaric acid, which are found in grapes, to soften the wine.

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In addition, the high concentration of alcohol prevents the development of yeasts and microorganisms that can harm the quality of the wine.

Wine is wine, thanks to the chemistry that goes with it.