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What are sulphites in wine?
Sulphites are the salts of sulphurous acid. They are formed when sulphur combines with water, which happens when the wine is sulphurised.
The addition of sulphur is a very effective method of preservation, stabilisation and sterilisation in winemaking. Sulphur is added to wine in the form of sulphur dioxide, sulphurous acid (sulphur dioxide dissolved in water) or potassium pyrosulphite (the potassium salt of sulphurous acid, abbreviated KPS).
Sulphurisation has three main functions:
- Sulphur binds oxygen and thus protects against Oxidationwhich can impair the flavour of the wine.
- Sulphur inhibits Enzymeswhich can have a negative influence on the development of wine.
- Sulphur removes Microorganisms(yeasts, bacteria, etc.) that can negatively influence wine development and spoil the wine.
Already in the vineyard, sulphur is used as the most effective remedy against fungal diseases such as powdery mildew - also in organic viticulture.
In the wine cellar, sulphur is used in various production steps. For example, the must or mash is already sulphurised to prevent uncontrolled fermentation or oxidation; after fermentation or pressing, the young wine is sulphurised to stabilise it; in the course of ageing, it is sulphurised again if necessary; and before bottling, it receives its final sulphurisation to preserve it.
How often and how much sulphur is added depends on a variety of factors - from the grape variety to the quality of the grapes, the production process, cellar hygiene and the desired ageing style. Through its reductive and antiseptic effect and its reaction with other chemical elements, sulphur also influences the smell and taste of the wine.
Many natural wines are treated with minimal or no sulphur. But if the winemaker does not add sulphur, the wine changes its aroma under the influence of oxygen and microorganisms. This is then characterised less by fruity notes and more by earthy and nutty tones.
The indication "contains sulphites" is required by law for wines that have been treated with sulphur. Sulphites are harmless to health in the quantities permitted by wine law. According to current scientific findings, they are not responsible for possible headaches after (excessive) wine consumption, but biogenic amines (e.g. histamine), which are also contained in wine.