Sodium Metabisulphite

1. Definition & Properties‌

• ‌Chemical Formula‌: Na₂S₂O₅, a white to slightly yellow crystalline powder with a strong SO₂ odor.

• ‌Solubility‌: Highly soluble in water (540 g/L at 20°C), forming an acidic solution.

• ‌Instability‌: Decomposes at >150°C, oxidizes to Na₂S₂O₆ in air, and releases SO₂ when exposed to acids

‌2. Primary Functions in Food‌

• ‌Preservative‌: Inhibits mold, yeast, and bacteria, extending shelf life in acidic foods (pH ≤4.5)

• ‌Antioxidant‌: Prevents enzymatic and non-enzymatic browning in fruits and vegetables

• ‌Bleaching Agent‌: Used to whiten sugar, starches, and dried fruits

‌3. Common Applications‌

• ‌Beverages‌: Carbonated drinks and fruit juices (prevents fermentation)

• ‌Processed Foods‌: Jams, pickles, and dried fruits (preserves color/texture)

• ‌Dairy & Bakery‌: Cheese and dough (controls microbial growth)