Product Overview
Sodium Metabisulfite Food Grade is a white crystalline powder that functions as a reducing agent and antioxidant across food processing, water treatment, and chemical manufacturing operations. Also known as Sodium Pyrosulfite or Disodium Metabisulfite, this inorganic salt (CAS 7681-57-4) releases sulfur dioxide on contact with water or acids — a property that drives its use as a preservative, a dechlorinating agent, and an oxygen scavenger.
This product is offered in the Food Grade designation and is available in pack sizes from 2 lb bags through 50 lb bags, serving bench-scale trials and full production runs alike. Alliance Chemical supplies Sodium Metabisulfite with a Safety Data Sheet, Technical Data Sheet, and lot-specific Certificate of Analysis for every order.
Why This Grade
The Food Grade designation tells a buyer that this Sodium Metabisulfite is procured through a supply chain intended for food-contact and beverage applications — a distinction that matters when your process touches consumables, potable water, or finished goods subject to regulatory review. Buyers in winemaking, juice processing, dried fruit preservation, and municipal dechlorination commonly specify Food Grade to satisfy their own quality programs and downstream audit requirements.
If your application is strictly industrial — photographic development, wastewater reduction, or chemical synthesis — a Food Grade product still performs, but you may be paying for a procurement pathway your process does not require. Match the grade to your end use and your facility's documentation needs.
Chemical Profile
Sodium Metabisulfite is a white crystalline or powder solid carrying a slight sulfur odor that becomes more pronounced as sulfur dioxide in the presence of even trace moisture. Its molecular formula is Na2O5S2 with a molecular weight of 190.11 g/mol. The powder is denser than water at a specific gravity of 1.4 and dissolves readily — solubility reaches 54% in water, making it straightforward to prepare working solutions at the concentrations most industrial processes demand. The material is noncombustible under normal conditions, but thermal decomposition at high temperatures can release toxic sulfur oxide and sodium oxide fumes. Contact with water produces a corrosive acidic solution. CAS Number: 7681-57-4.
Industrial Applications
Sodium Metabisulfite's value comes from its ability to release sulfur dioxide in a controlled, measurable way. That single mechanism supports a range of industrial processes:
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Food Preservation — In fruit and vegetable processing, Sodium Metabisulfite acts as a preservative and antioxidant by inhibiting enzymatic browning reactions. Operators add it to wash water, dipping solutions, or directly to product during processing to extend shelf life and maintain appearance.
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Wine and Beverage Production — Winemakers rely on it as an antioxidant and antimicrobial agent during crush, fermentation, and bottling. It scavenges dissolved oxygen and suppresses spoilage organisms, stabilizing the finished product through storage.
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Water Treatment and Dechlorination — Municipal and industrial water operators use Sodium Metabisulfite as a dechlorinating agent to neutralize residual chlorine and chloramine in treated water before discharge or reuse. The reaction is fast and stoichiometrically predictable.
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Photographic Development — In darkroom chemistry, it serves as a reducing agent in developer formulations and as a preservative in stop bath and fixer solutions, preventing premature oxidation of active chemicals.
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Chemical Synthesis — Sodium Metabisulfite participates as a reducing agent in organic and inorganic synthesis, particularly in sulfonation reactions, aldehyde purification, and metal recovery processes.
Handling & Storage
Sodium Metabisulfite carries a Danger signal word (per the product's GHS classification) with hazard statements H302 (harmful if swallowed) and H318 (causes serious eye damage) (per the product's GHS classification). These are not optional warnings — treat them as baseline handling requirements.
Operators should wear chemical-splash goggles and impervious gloves at minimum. In dusty or poorly ventilated conditions, use NIOSH-approved respiratory protection rated for particulate and SO2 — this powder releases sulfur dioxide gas on contact with moisture or acids, and inhalation is a real hazard in confined or humid environments.
Store in a cool, dry area in tightly sealed containers. Sodium Metabisulfite is hygroscopic and degrades on moisture exposure, losing active SO2 content and caking in the bag. Keep it segregated from strong acids, strong bases, and oxidizers — acid contact accelerates SO2 release, and oxidizer contact can produce a vigorous reaction. Shelf life is directly tied to how well you keep moisture out.
Hazmat & Shipping
Sodium Metabisulfite Food Grade is not classified as a DOT hazardous material for transport (per 49 CFR 172.101) — it carries no UN number, no hazard class, and no packing group under the Hazardous Materials Table. This simplifies carrier acceptance and routing compared to regulated shipments.
Note that a non-regulated transport classification governs only the DOT shipping designation. Carrier policies, facility receiving requirements, and any state or local rules still apply independently. Alliance Chemical ships from Taylor, TX, and all shipping guidance on this page is reviewed by Andre Taki, DOT Hazmat Specialist.
Documentation
Every order of Sodium Metabisulfite Food Grade ships with a Safety Data Sheet (SDS) in English and a lot-specific Certificate of Analysis (COA). A Technical Data Sheet (TDS) is also available. These documents support your incoming QC process, regulatory file, and downstream audit trail — request them at the time of order or contact our team for advance copies.
Why Buy from Alliance Chemical
This Sodium Metabisulfite is available in pack sizes from 2 lb bags for bench trials and small-batch use through 50 lb bags for production-scale operations — with SDS, TDS, and lot-specific COA documentation included. Alliance Chemical has served over 50,000 customers since 1998, shipping from our warehouse at 204 S Edmond St, Taylor, Texas 76574. Product and shipping guidance on this page is reviewed by Andre Taki, DOT Hazmat Specialist (USDOT #2188383).
