Sulfite Treatment

(in the food industry), the preservation of fruits and vegetables using sulfur dioxide, SO₂, sulfurous acid, H₂SO₃, and sodium bisulfite, NaHSO₃. Sulfites in concentrations of 0.1–0.2 percent by weight in an acid medium eliminate molds and yeasts, which cause spoilage of fruits and vegetables. The treatment is carried out by the dry method, in which the food is exposed to sulfur dioxide in wood or stone chambers, or the wet method, in which fruits or berries are placed in barrels and covered with a weak solution of sulfurous acid or sodium bisulfite.

Sulfite treatment is used in the summer and autumn, mainly for fruit products, such as purees, juices, and cut and whole fruits and berries, that are intended for processing during the winter. In the USSR, sulfite treatment is not permitted for items to be used in baby foods or dietary foods.

Sulfite treatment is being replaced by other methods of preservation—for example, refrigeration, freezing, pasteurization, and sterilization—and by the use of such harmless chemical preservatives as sorbic acid.