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Sulphur Dioxide is a colorless, pungent inorganic gas widely used as a preservative, antioxidant, bleaching agent, and process aid in food and beverage manufacturing and in several industrial processes.
Sulphur Dioxide is valued because Sulphur Dioxide inhibits yeasts and molds, slows oxidative browning, and helps preserve color and flavor in many products, especially acidic foods and beverages.
Sulphur Dioxide must be handled with extreme care because Sulphur Dioxide is toxic and strongly irritating to the respiratory tract, and Sulphur Dioxide exposure can trigger severe asthma-like reactions in sensitive individuals, so Sulphur Dioxide use requires strict ventilation, monitoring, and regulatory compliance.
CAS Number: 7446-09-5
EC Number: 231-195-2
Molecular Formula: SO2
Molecular Weight: 64.07 g/mol
Synonyms: Sulphur Dioxide, Sulfur Dioxide (US spelling), SO2, E220, Sulfurous Anhydride (historical), Sulphur Dioxide Gas, Sulfur Dioxide Preservative, Sulfur Dioxide Antioxidant, Sulfur Dioxide Bleaching Agent, Sulfur Dioxide Fumigant, Sulphur Dioxide E220, Sulfur Dioxide Food Additive, Sulphur Dioxide, Sulfur Dioxide, Sulphur Oxide, Sulfur Oxide, Sulphurous Anhydride, Sulfurous Anhydride, Sulfurous Oxide, Sulphurous Oxide, Sulfurous Acid Anhydride, Sulphurous Acid Anhydride, Sulfurous Acid Gas, Sulphurous Acid Gas, Sulphur Dioxide Gas, Sulfur Dioxide Gas, Liquid Sulphur Dioxide, Liquid Sulfur Dioxide, Sulphur Dioxide Refrigerant, Sulfur Dioxide Refrigerant, Sulphur Dioxide Food Grade, Sulfur Dioxide Food Grade, Sulphur Dioxide Technical Grade, Sulfur Dioxide Technical Grade, Sulphur Dioxide Industrial Grade, Sulfur Dioxide Industrial Grade, Sulphur Dioxide Preservative, Sulfur Dioxide Preservative, Sulphur Dioxide Antioxidant, Sulfur Dioxide Antioxidant, Sulphur Dioxide Fumigant, Sulfur Dioxide Fumigant, Sulphur Dioxide Bleaching Agent, Sulfur Dioxide Bleaching Agent, Sulphur Dioxide E220, Sulfur Dioxide E220, E220, INS 220, Sulphurous Gas, Sulfurous Gas, Sulfur Oxide (IV), Sulphur Oxide (IV), Sulfurous Acid Former, Sulphurous Acid Former, Anhydrous Sulphur Dioxide, Anhydrous Sulfur Dioxide, Sulphur Dioxide Solution
APPLICATIONS
Sulphur Dioxide is used in winemaking to control microbial growth and to protect wine from oxidation during production and storage.
Sulphur Dioxide is incorporated into wine as free and bound sulfite forms to stabilize color and flavor and to reduce spoilage risk.
Sulphur Dioxide is used in must and wine processing to inhibit unwanted yeasts and bacteria while desired fermentation is controlled.
Sulphur Dioxide is used in dried fruits to prevent enzymatic browning and to preserve light color and flavor during storage.
Sulphur Dioxide is incorporated into dried apricots, raisins, and other dried fruits to inhibit molds and extend shelf life.
Sulphur Dioxide is used in fruit processing as a bleaching and antioxidant treatment where regulations allow.
Sulphur Dioxide is used in fruit juices and concentrates to inhibit microbial growth and to protect against oxidation in compatible products.
Sulphur Dioxide is incorporated into juice processing to stabilize color and reduce off-flavor formation.
Sulphur Dioxide is used in juice and puree manufacturing where sulfite management and labeling are controlled.
Sulphur Dioxide is used in potato products to prevent browning and discoloration during processing and storage.
Sulphur Dioxide is incorporated into dehydrated potatoes and potato flakes to maintain color and reduce oxidative changes.
Sulphur Dioxide is used in cut potato treatment systems to reduce enzymatic browning.
Sulphur Dioxide is used in seafood processing to prevent melanosis in shrimp and to reduce discoloration.
Sulphur Dioxide is incorporated into anti-melanosis treatments as part of sulfite-based process aids in regulated applications.
Sulphur Dioxide is used in crustacean processing where sulfite residue limits and labeling rules are followed.
Sulphur Dioxide is used in sugar processing and food starch processing as a bleaching and purification aid in compatible operations.
Sulphur Dioxide is incorporated into process streams to control color bodies and to reduce oxidative degradation of sensitive components.
Sulphur Dioxide is used in food ingredient processing where residual sulfite limits are controlled.
Sulphur Dioxide is used in bakery and dough processing in some contexts to improve flour treatment and to control microbial activity in compatible systems.
Sulphur Dioxide is incorporated into specialized bakery ingredient processing where sulfite is permitted as a processing aid.
Sulphur Dioxide is used in fermented foods to inhibit wild microbes when fermentation is tightly managed.
Sulphur Dioxide is used in industrial bleaching and reducing processes such as pulp and paper processing to remove color bodies and reduce oxidized species.
Sulphur Dioxide is incorporated into sulfonation-related and reduction processes where controlled reducing chemistry is required.
Sulphur Dioxide is used in water treatment as a dechlorination and reducing agent in controlled applications.
Sulphur Dioxide is used in chemical manufacturing as an intermediate or reagent in sulfite and bisulfite production.
Sulphur Dioxide is incorporated into sodium metabisulfite and sodium bisulfite manufacturing chains.
Sulphur Dioxide is valued because Sulphur Dioxide provides strong antioxidant and antimicrobial benefits, but Sulphur Dioxide use requires strict hazard controls and regulatory compliance.
Sulphur Dioxide is used as an antimicrobial preservative in winemaking.
Sulphur Dioxide inhibits spoilage yeasts and bacteria in must and wine.
Sulphur Dioxide helps protect wine quality by controlling unwanted fermentation and microbial growth.
Sulphur Dioxide is used as an antioxidant in wine to limit oxidative browning.
Sulphur Dioxide scavenges oxygen and reactive oxidation intermediates in wine.
Sulphur Dioxide helps preserve aroma and color stability during storage and transport.
Sulphur Dioxide is used in cider and perry production to control microbial spoilage.
Sulphur Dioxide supports stable fermentation management by suppressing wild microbes.
Sulphur Dioxide helps improve shelf life of finished cider products.
Sulphur Dioxide is used in fruit juice processing to prevent enzymatic browning.
Sulphur Dioxide inhibits polyphenol oxidase-driven browning in sensitive juices.
Sulphur Dioxide helps maintain light color and fresh taste in certain juice products.
Sulphur Dioxide is used in dried fruit processing to preserve color and reduce spoilage.
Sulphur Dioxide prevents darkening of apricots, raisins, and other dried fruits.
Sulphur Dioxide helps maintain visual appeal and extends shelf life of dried fruits.
Sulphur Dioxide is used in dehydration of fruit slices to maintain brightness and reduce microbial risk.
Sulphur Dioxide supports stable color retention during drying and storage.
Sulphur Dioxide helps reduce mold growth on dried fruit products.
Sulphur Dioxide is used in potato processing to prevent enzymatic browning in cut potatoes.
Sulphur Dioxide supports color retention in potato flakes and dehydrated potato products.
Sulphur Dioxide helps reduce discoloration during processing and storage in controlled applications.
Sulphur Dioxide is used in shrimp and seafood processing to reduce melanosis in some systems.
Sulphur Dioxide supports prevention of black spot formation in crustaceans where permitted.
Sulphur Dioxide helps maintain appearance during chilled storage and distribution.
Sulphur Dioxide is used in sugar processing as a bleaching and clarifying aid in some refineries.
Sulphur Dioxide supports decolorization of sugar syrups during refining steps.
Sulphur Dioxide helps produce lighter-colored sugar products in controlled processes.
Sulphur Dioxide is used in starch and syrup production as a process aid in some systems.
Sulphur Dioxide supports viscosity control and color management in syrup manufacture.
Sulphur Dioxide helps reduce microbial load in process streams under controlled conditions.
Sulphur Dioxide is used in brewing in some contexts to control oxidation and microbial contamination in specific steps.
Sulphur Dioxide supports stability of certain beer styles when applied under strict process control.
Sulphur Dioxide helps protect flavor stability by limiting oxidative reactions in niche uses.
Sulphur Dioxide is used in vinegar production as a microbial control aid during storage of raw materials.
Sulphur Dioxide supports suppression of unwanted microbes in fruit-based vinegar feedstocks.
Sulphur Dioxide helps reduce spoilage risk before controlled fermentation.
Sulphur Dioxide is used in food preservation as a sulfiting agent for acidified foods.
Sulphur Dioxide supports inhibition of yeasts and molds in sensitive acidic products.
Sulphur Dioxide helps extend shelf life where regulations permit sulfite use.
Sulphur Dioxide is used in bakery and confectionery as a sulfite source through permitted sulfite ingredients.
Sulphur Dioxide supports dough conditioning effects in certain bakery processes via sulfite chemistry.
Sulphur Dioxide helps manage browning and texture in niche regulated applications.
Sulphur Dioxide is used in pulp and paper manufacturing as a chemical in sulfite pulping.
Sulphur Dioxide supports delignification by forming bisulfite species that solubilize lignin.
Sulphur Dioxide helps produce pulp grades with specific brightness and fiber properties.
Sulphur Dioxide is used in the production of sulfite and bisulfite salts such as sodium bisulfite.
Sulphur Dioxide supports manufacture of reducing agents used in water treatment and industry.
Sulphur Dioxide helps supply key sulfite chemicals for multiple industrial sectors.
Sulphur Dioxide is used in water treatment as a dechlorinating agent via sulfite/bisulfite chemistry.
Sulphur Dioxide supports removal of residual chlorine and chloramines in treated water streams.
Sulphur Dioxide helps protect downstream processes that are sensitive to oxidizing disinfectants.
Sulphur Dioxide is used in boiler water and industrial process water to control oxidants in some systems.
Sulphur Dioxide supports oxygen scavenging and reduction of oxidative corrosion drivers.
Sulphur Dioxide helps stabilize water chemistry when applied under controlled dosing programs.
Sulphur Dioxide is used in mining and hydrometallurgy as a reducing agent in some leaching and precipitation steps.
Sulphur Dioxide supports control of redox potential in metal recovery processes.
Sulphur Dioxide helps improve selectivity of certain metallurgical reactions.
Sulphur Dioxide is used in chemical manufacturing as a precursor to sulfuric acid production.
Sulphur Dioxide supports oxidation to sulfur trioxide and subsequent acid formation in contact processes.
Sulphur Dioxide helps supply large-scale sulfuric acid plants with feed gas.
Sulphur Dioxide is used in production of sodium dithionite and related reducing agents in some industrial routes.
Sulphur Dioxide supports generation of sulfite intermediates used in reduction chemistry.
Sulphur Dioxide helps provide bleaching and reducing chemicals for textile and paper sectors.
Sulphur Dioxide is used in textile processing as a bleaching and reducing agent in some applications.
Sulphur Dioxide supports reduction of color bodies and removal of residual oxidants.
Sulphur Dioxide helps improve whiteness and shade control in certain textile operations.
Sulphur Dioxide is used in leather processing as a reducing agent and preservative aid in some steps.
Sulphur Dioxide supports color control and microbial suppression in specific leather operations.
Sulphur Dioxide helps improve processing stability in controlled, regulated uses.
Sulphur Dioxide is used in laboratory chemistry as a reducing agent and reagent for sulfite chemistry studies.
Sulphur Dioxide supports preparation of sulfite and bisulfite solutions for analytical work.
Sulphur Dioxide helps demonstrate redox reactions and gas–liquid equilibrium in teaching labs.
DESCRIPTION
Sulphur Dioxide is a colorless gas with a sharp, choking odor, and Sulphur Dioxide dissolves in water to form sulfurous acid and bisulfite/sulfite species depending on pH.
Sulphur Dioxide preservative performance depends on free SO2 and bisulfite availability, and these forms provide antimicrobial action and antioxidant protection in acidic foods and beverages.
Sulphur Dioxide is effective at inhibiting yeasts and molds and also reduces enzymatic and non-enzymatic browning by reacting with oxygen and carbonyl intermediates.
Sulphur Dioxide can be introduced directly as gas or generated from sulfite salts such as sodium metabisulfite, and dosing strategy depends on process design and target free SO2 level.
Sulphur Dioxide can react with aldehydes, sugars, and phenolic compounds, leading to bound forms that reduce free SO2 availability, so monitoring and adjustment are important in systems like wine.
Sulphur Dioxide is strictly regulated in foods due to allergen risks, and labeling and residue limits must be followed in each market.
Sulphur Dioxide is highly irritating and toxic by inhalation, so Sulphur Dioxide handling requires gas-tight systems, scrubbing, ventilation, and leak monitoring.
Sulphur Dioxide cylinders and bulk systems must be handled with specialized training, and emergency response planning is essential.
Sulphur Dioxide should be stored and used in accordance with local safety codes and food additive regulations for the intended application.
Sulphur Dioxide is a colorless gas with a sharp, choking odor and strong irritating properties.
Sulphur Dioxide dissolves in water to form sulfurous acid and bisulfite species.
Sulphur Dioxide acts as a reducing agent and antioxidant in many chemical and food systems.
Sulphur Dioxide is widely used as a sulfiting agent in foods and beverages, especially wine and dried fruits.
Sulphur Dioxide antimicrobial activity targets many yeasts and bacteria and depends strongly on pH.
Sulphur Dioxide effectiveness is often described in terms of free and bound sulfite fractions in solution.
PROPERTIES
Chemical Formula: SO2
Molecular Weight: 64.07 g/mol
Common Name: Sulphur Dioxide (Sulfur Dioxide)
Chemical Type: Inorganic gas; preservative; antioxidant; reducing agent
Appearance: Colorless gas
Odor: Sharp, choking, pungent odor
Solubility: Highly soluble in water; forms sulfurous acid and sulfite/bisulfite species
Acidity: Forms acidic solutions in water; pH dependent equilibria
Preservative Activity: Antimicrobial against yeasts and molds; antioxidant and anti-browning effects
Reactivity: Reducing agent; reacts with oxidizers; reacts with aldehydes and carbonyls; can form sulfites/bisulfites
Health Considerations: Toxic and strongly respiratory irritant; can trigger severe reactions in asthmatics
Storage Form: Compressed liquefied gas in cylinders or bulk tanks
Storage Temperature: Store cool and secured; protect cylinders from heat and physical damage
Shelf Life: Not typically limited for cylinder gas when properly stored; system dependent for solutions
FIRST AID
Inhalation:
Move to fresh air immediately and keep at rest.
Seek immediate medical attention because Sulphur Dioxide inhalation can cause severe respiratory irritation and delayed effects.
If breathing is difficult, oxygen may be needed by trained personnel, and symptoms can worsen after exposure ends.
Skin Contact:
If contact with liquefied gas occurs, treat as cold burn and rinse with lukewarm water.
Remove contaminated clothing and seek medical attention for burns or irritation.
For solutions, wash with soap and water and seek medical advice if irritation persists.
Eye Contact:
Rinse cautiously with water for at least 15 minutes, holding eyelids open.
Remove contact lenses if present and easy to do, then continue rinsing.
Seek immediate medical attention because eye exposure can cause severe injury.
Ingestion:
Ingestion is unlikely for gas, but sulfite solutions can be swallowed.
Rinse mouth with water and seek medical attention promptly.
Do not induce vomiting unless directed by medical personnel.
Note to Physicians:
Treat symptomatically and monitor respiratory function for delayed pulmonary effects.
Consider bronchospasm risk and provide supportive care.
Observe exposed individuals for delayed respiratory distress.
HANDLING AND STORAGE
Handling:
Use only in closed systems with appropriate gas handling equipment, and never intentionally inhale Sulphur Dioxide.
Use appropriate PPE including chemical goggles or face shield and suitable gloves, and use respiratory protection as required by risk assessment.
Ensure emergency eyewash and shower facilities are available near use areas.
Ventilation:
Use strong local exhaust ventilation and ensure adequate general ventilation.
Install gas detection and alarms where Sulphur Dioxide is used or stored.
Use scrubbers or neutralization systems for exhaust to prevent environmental release.
Storage:
Store cylinders upright, secured, and in a cool, well-ventilated area away from heat and sunlight.
Segregate from oxidizers and incompatible chemicals and protect cylinders from physical damage.
Keep valves closed when not in use and use correct regulators and fittings designed for Sulphur Dioxide service.
Spill and Leak Procedures:
Evacuate area, ventilate, and stop leak only if trained and it is safe to do so.
Use emergency response procedures and gas scrubbers where available.
Do not allow gas to enter occupied areas and notify emergency services if release is significant.
Handling Precautions:
Monitor free SO2 and total sulfite where required in food systems to meet residue limits and labeling requirements.
Implement strict worker protection because Sulphur Dioxide can cause severe respiratory harm at low exposure levels.
Maintain equipment integrity and preventive maintenance because leaks are a critical hazard for toxic gases.
