Sodium Metabisulfite Supplier in South Africa

What Is Sodium Metabisulfite?

Sodium metabisulfite (Na₂S₂O₅), also known as sodium pyrosulfite, is a white crystalline powder that is the anhydrous form of sodium bisulfite, releasing sulfur dioxide in the presence of water or acid. With SO₂ content of ≥64%, it is a highly concentrated and stable SO₂ carrier used as a preservative, antioxidant, bleaching agent, and reducing agent across food, beverage, water treatment, pharmaceutical, and mining industries. It is registered as food additive E223 and is among the most widely used sulfite compounds globally.

Food, Beverage & Wine Industry

In food processing, sodium metabisulfite preserves dried fruits, vegetables, and juices against browning and microbial spoilage. In brewing, it is added to wort to prevent oxidation. In winemaking, it is dissolved to produce sulfiting solution for barrel sanitation and wine stabilisation between fermentations. In seafood processing, it prevents black spot (melanosis) in prawns and crustaceans during storage and distribution. Regulatory limits on SO₂ content vary by food category and jurisdiction; Terracore supplies certificates of analysis to assist compliance.

Water Treatment & Mining

Sodium metabisulfite is used for dechlorination of drinking water and process effluents, reacting with residual chlorine quickly and without introducing harmful by-products. In mining, it is an important flotation depressant used in the selective flotation of precious metal and base metal sulfide ores, where it is added to the flotation circuit to depress pyrite and arsenopyrite while floating gold-bearing minerals. It is also used in cyanide detoxification of gold mine tailings (reducing CN⁻ in the Inco SO₂/Air process).

Pharmaceutical & Industrial Reducing Agent

Pharmaceutical-grade sodium metabisulfite is used as an antioxidant and preservative in injectable formulations, topical preparations, and oral liquids to prevent oxidative degradation of active ingredients. In industrial chemistry it reduces chromate waste streams from electroplating to trivalent chromium (Cr³⁺) for safe precipitation and disposal. It is also used in photography as a preservative, in rubber vulcanisation, in textile printing discharge pastes, and in paper pulp bleaching.