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The sulphur (or sulfur dioxide under its chemical name) has great interest in oenology, that is why it is commonly used during the vinification of the grapes until the bottling. Among its properties include being an anti-microbial agent (it allows to limit the development of bacteria and yeast may affect the wine), but also antioxidant (it protects against oxidation and contributes to the conservation of the colour and aromas of the wine).
Pierre-Louis Teissedre, professor of universities, oenologist © DRUn wine with a low antioxidant protection (in other words, a wine for which the amount of sulphur dioxide given would not be sufficient to protect it) is more exposed to the risk of development of diseases that lead to organoleptic deviations including the vent, the taste of mice, the smell of leather/horse sweat, the vinegar (which can make the wine unfit for consumption)... A too low amount of sulfur may change the taste of the wine in a bad sense. Conversely, a too large amount of sulfur (respecting of course the maximum force) will mask the aromas of the wine by combination with other compounds that will produce the aromas of apple, beet, and nuts. It can also, in excess, generate an irritating smell similar to that of a match that they just rub.
The sulphur dioxide may also be used to avoid re-fermentation of sweet wines, sometimes linked to a change in temperature. Although it is possible to make wine without adding sulfur dioxide, it is not possible to produce a wine with no sulfur dioxide. This is due to the fact that the yeast produces a small amount, at least 10 mg/liter during the fermentation. It is for this reason that the labelling of the presence of sulphites or sulphur dioxide in wine bottles is compulsory from 10 mg/liter to prevent the people who may have allergies or food intolerances. Although several treatment by chemical, physical or biological are tested on grape must or wine, there is currently no alternative treatment universal to replace the sulphur dioxide and to ensure its functionality. The desire of consumers to see to decrease the use of inputs (additives/auxiliaries) in the development and conservation of the wines is not always compatible with the research of the sensory quality of wines.
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