Sulfur dioxide (SO2) is a colorless, pungent gas widely used in the food industry as a preservative, antioxidant, and antimicrobial agent, particularly in dried fruits, wine, and juices to prevent oxidation and microbial spoilage. Chemically, it is the anhydride of sulfurous acid and readily dissolves in water to form H2SO3. It acts by inhibiting enzymatic browning and destroying bacteria, yeasts, and molds. In food applications, it is regulated (E220) with strict residue limits due to potential allergic reactions in sensitive individuals. Industrially, it is produced by burning sulfur or roasting sulfide ores and serves as a precursor for sulfuric acid. Its high reactivity allows it to act as a reducing agent and bleaching compound in various processes.