Nátriummetabiszulfit

Nátriummetabiszulfit, also known as sodium metabisulfite, is an inorganic compound with the chemical formula Na₂S₂O₅. It is a white, crystalline powder that is highly soluble in water and commonly used as a preservative, antioxidant, and bleaching agent in various industries. Structurally, it consists of two sulfite ions (SO₃²⁻) linked by a sulfur atom, forming a bisulfite structure that readily dissociates in aqueous solutions to release sulfur dioxide (SO₂), a key active component.

The compound is widely utilized in the food industry as an antioxidant (E-number E223) to prevent oxidation and spoilage in dried fruits, wines, and processed foods. It also serves as a bleaching agent for textiles, paper, and straw, helping to remove color and brighten materials. In winemaking, sodium metabisulfite is employed to inhibit microbial growth and prevent oxidation during fermentation and storage. Additionally, it finds applications in pharmaceuticals, photography, and water treatment, where it helps control microbial activity and oxidation.

Sodium metabisulfite is produced industrially through the reaction of sodium sulfite with sulfuric acid or by heating sodium bisulfite. It is generally considered safe for food use within regulated limits, though excessive intake may cause allergic reactions or respiratory issues in sensitive individuals. Proper handling is recommended due to its corrosive nature and potential to release toxic sulfur dioxide gas when exposed to acids.

The compound decomposes upon heating, releasing sulfur dioxide, and reacts with oxidizing agents. It is stored in airtight containers away from moisture and strong oxidizers to maintain stability. Due to its versatility, sodium metabisulfite remains a fundamental chemical in numerous industrial and food preservation processes.