History of wine - Composition of wine and must (5)
Phenolic compounds
A benzene ring with an alcoholic group, phenol is the central component of many chemical products in wine. In addition to carbohydrates and acids, it is one of the most important compounds.
Because they are present in grape skins and seeds (seeds), polyphenols affect the aromas, flavors and other sensory qualities of wine. During winemaking, winemakers pay close attention to polyphenol levels, as they change throughout the winemaking processes.
The concentration of polyphenols in the must depends largely on the variety of Vitis vinfera and the climate in which it was cultivated. The concentration and proportion of the different polyphenols also depend largely on how the grape was processed.
For example, the concentration of polyphenols in white wines that have had little contact with grape skin is different from that observed in red wines.
Tannins are highly reactive phenolic compounds. In solution, they can interact with proteins and precipitate. Anthocyanins, which color wines, are another phenolic compound. Anthocyanins are naturally colored substances that can be bleached (become colorless) using a series of chemical agents or methods, such as oxidation and reduction, that maintain their color (turning).
Phenols are important for wine oxidation processes (phenolic oxidation) and are among the most common reactions in the aging of red wines.
Inorganic constituents
In the analysis of wine, the ash content is usually analyzed, which turn out to be the inorganic waste of the wine. Most of the compounds are carbonates and oxides. In the fruits of Vitis vinifera, most of it is potassium.
In many cases, the potassium content is altered by climate changes; for example, warm regions have a higher potassium content than cold regions. During vinification, sulfur dioxide (SO2) is generated as a gas in quantities ranging from 12 to 64 mg/liter and is used as a fumigant in vats.
Traces of lead have been found in wine bottles as a result of capsules leaking through the cork stopper.