FermenteaWhere food goes to change
Preservatives
Sulphur dioxide and its sulphite salts are used to inhibit some microbes and oxidation and to keep colour in fruit and wine. They are added as sulphur fumes, as sulphites or as metabisulphites.
Sulphur dioxide is a gas that dissolves in water to form sulphurous acid and its salts. In food it is supplied as the gas from burning sulphur, or as sulphite and metabisulphite salts that release it in solution. Its preserving role comes from inhibiting some microorganisms and from slowing oxidation, and it helps fruit keep its colour.
It is an additive and a process chemical rather than a food in its own right, so it appears on this page as an ingredient that is bought and used, not as a recipe.
The catalogue records sulphur-derived compounds in historical winemaking and in later commercial fruit processing. Sulphuring fruit and using sulphites in liquids are the two forms it describes. Sulphuring fruit is not the same as smoking it over wood: the catalogue states that the two processes are different.
Its effect is strongest when it is combined with other steps. The catalogue links sulphur treatment with drying in fruit and with fermentation in beverages, so it works as one control among several rather than as a complete preservative on its own.
The record does not give concentrations, contact times or the amount to use for any product, and this page does not supply them.
Sulphites can cause reactions in people who are sensitive to them, and the catalogue does not set a threshold. Labelling and dose control belong to the product and the jurisdiction, and neither is recorded here. A treated product should not be used to judge whether a batch is safe, because smell, colour and taste do not show it.
Sulphites are a labelled allergen and irritant for some people; the catalogue does not give thresholds.
The catalogue places sulphuring in historical winemaking and later commercial fruit processing, without a single locality.
Cheese, tofu, agar, nixtamal and cured ham all begin with a liquid or soft food made to set, sour or keep. Rennet is one branch of that history, beside plant enzymes, acids, minerals, alkalis, gels, finings and curing salts.
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Food and Agriculture Organization of the United NationsMethod · History · Safety
FAO document v5030e, chapter 0dSulphur-derived compounds inhibit some microbes and oxidation and help retain colour, often in combination with drying or beverage fermentation.
The process includes sulphuring fruit and using sulphites in liquids; it is not equivalent to ordinary wood smoking.
Cited in: What it is; Historical use; How it works in a preparation; Limits and safety
Food and Agriculture Organization of the United NationsMethod
FAO document AE618eCited in the catalogue for sulphur-treated processes alongside drying and fruit handling.