1. Food & Healthcare Ingredients

• Preservative: It kills or inhibits the growth of bacteria, molds, and yeasts, preventing spoilage in foods and beverages. 
• Antioxidant: It neutralizes oxygen, preventing oxidation that can lead to discoloration and flavor degradation. 
• Color and Freshness: It preserves the natural, vibrant color of dried fruits (like apricots and raisins) and juices, preventing them from turning brown. 
• Flavor Preservation: It helps maintain the delicate flavors of dehydrated foods and beverages like wine and beer.

2. Water Treatment

• Dechlorination: Potassium metabisulfite neutralizes free chlorine and chloramines, which are powerful disinfectants and oxidizing agents. This is crucial for protecting sensitive equipment in industries like pharmaceuticals and semiconductors, as well as for treating irrigation water that can harm plants. 
• Reducing Agent & Oxygen Scavenging: It acts as a reducing agent, neutralizing oxidizing agents that increase chemical oxygen demand (COD) in wastewater. It also removes dissolved oxygen from water, which is essential for preventing corrosion in boilers, pipes, and other industrial systems.

3. Fabric Solutions

• Bleaching: The compound removes yellowing and discoloration from natural fibers like wool, cotton, and silk, preparing them to take on a uniform and vibrant dye color. 
• Indigo Dyeing: It converts indigo dye into its reduced, water-soluble form, which is essential for the dye to attach to textile fibers properly. 
• Desizing: Potassium metabisulfite helps in the removal of certain substances from fabrics before dyeing. 
• Color Fixation: It improves the intensity of the dye color by stabilizing the dye's bond to the fibers. 
• Antioxidant: It prevents dyes from oxidizing prematurely, thus maintaining their dyeing power. 
• Dechlorination: Potassium metabisulfite is also used in the process of de-chlorinating fabrics.

4. Pharmaceuticals

• Antioxidant/Stabilizer: Potassium metabisulfite prevents oxidation in liquid formulations, which can lead to changes in color, odor, and therapeutic properties of medications. 
• Preservative: By releasing sulfur dioxide when dissolved in water, it creates an antimicrobial environment that inhibits the growth of fungi and bacteria, thus preserving the product and extending its shelf life.

5. Performance Chemicals

• Sulfur Dioxide Source: Potassium metabisulfite readily provides SO₂ in reactions, making it a safer and easier-to-handle alternative to gaseous SO₂. 
• Sulfonylation Reactions: It is a key reagent in sulfonylation, where it reacts with alkenes and alcohols to form sulfonate esters. 
• Radical-Mediated Transformations: Many reactions using potassium metabisulfite proceed through radical processes, facilitating the insertion of SO₂ into other molecules.