Chemical laboratory

Sodium Metabisulfite Food

Food-Grade Preservative and Antioxidant for Food Processing

  • CAS 7681-57-4
  • Formula Na₂S₂O₅
  • Flash Pt N/A °C
  • Density 1.48 g/cm³
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Physical & Chemical Properties

Property Value Unit
Boiling point N/A (Decomposes) °C
Flash point N/A °C
Density 1.48 g/cm³ g/cm³
Solubility 65.2 g/100 mL (20°C) -
Ph 4 - 5 (10% solution) -
Molecular weight 190.10 g/mol g/mol
Melting point N/A °C
Vapor pressure N/A mmHg
Autoignition temp N/A -
Appearance White crystalline powder -
Odor Pungent, sulfurous odor -
Vapor density N/A g/cm³

Overview

Sodium Metabisulfite Food (Na₂S₂O₅) is a white crystalline powder with a pungent, sulfurous odor, widely used as a food-grade preservative and antioxidant in the food processing industry. With its molecular weight of 190.10 g/mol and excellent water solubility of 65.2 g/100 mL at 20°C, this versatile compound serves as an effective reducing agent and antimicrobial preservative. The compound decomposes rather than melts or boils, making it ideal for applications requiring controlled release of sulfur dioxide.

Key Applications

Sodium Metabisulfite Food serves multiple critical functions across various industries. In food processing, it acts as a powerful preservative and antioxidant, preventing oxidation and extending shelf life of dried fruits, wines, and processed foods. The compound is extensively used in winemaking as a sanitizing agent and to prevent unwanted fermentation by wild yeasts and bacteria. In industrial applications, it functions as a bleaching agent for textiles and paper, while also serving as an effective reducing agent in various chemical processes. Water treatment facilities utilize sodium metabisulfite for wastewater treatment and as a dechlorinating agent to neutralize chlorine in municipal water systems.

Safety & Handling

Sodium Metabisulfite Food is non-flammable with no flash point, autoignition temperature, or vapor pressure concerns. However, proper safety protocols are essential due to its potential to release sulfur dioxide gas upon decomposition. Workers should wear appropriate personal protective equipment including safety glasses, gloves, and dust masks to prevent inhalation of particles. Adequate ventilation is crucial in work areas to prevent accumulation of sulfur dioxide vapors. The compound maintains a pH of 4-5 in 10% solution, indicating mild acidity that requires careful handling to avoid skin and eye irritation.

Storage & Shelf Life

Store Sodium Metabisulfite Food in tightly sealed containers in a cool, dry location away from direct sunlight and moisture. The compound should be kept separate from strong oxidizers and acids to prevent unwanted reactions. Ideal storage temperature is at room temperature with low humidity to prevent caking and degradation. When stored properly in original packaging, the product maintains its effectiveness for extended periods. Regular inspection for signs of moisture absorption or discoloration ensures product quality and performance.

Why Alliance Chemical

Alliance Chemical provides reliable supply of high-quality Sodium Metabisulfite Food with same-day shipping from our Taylor, Texas facility. We offer flexible shipping options including UPS for smaller quantities and LTL/FTL freight services for bulk orders. Every shipment includes comprehensive Safety Data Sheets (SDS) and Certificates of Analysis (COA) to ensure compliance and quality assurance for your food processing and industrial applications.

Shipping & Availability

Parcel Shipping

UPS Ground supports pints, quarts, and most 1-gallon packages nationwide.

LTL Freight

5-gallon pails, drums, and totes move via LTL carriers such as ABF Freight, SEFL, Saia, and XPO.

Full Truckload

FTL available for palletized bulk orders. Competitive freight rates.

Local Pickup

Same-day pickup at our Taylor, TX warehouse for Texas customers.

SDS, COA, and TDS available for every product • Same-day shipping on orders before 1 PM CT

Frequently Asked Questions

What is Sodium Metabisulfite - Food (Na2S2O5) and what is it used for?
Sodium Metabisulfite (Na2S2O5, CAS 7681-57-4) is a white to off‑white crystalline powder used as a reducing agent, antioxidant, preservative and bleaching agent in food processing and in various industrial and laboratory applications.
How should food‑grade sodium metabisulfite be stored and what is its typical shelf life?
Store in a cool, dry, well‑ventilated area in tightly sealed containers away from heat and moisture; keep out of direct sunlight and away from acids and oxidizers. Shelf life depends on packaging and storage but is commonly 12–24 months if unopened and stored under recommended conditions.
What safety precautions and personal protective equipment are needed when handling this chemical?
Use local exhaust ventilation or work in a fume hood, wear chemical‑resistant gloves, safety goggles and a dust mask or respirator for dusty conditions, and avoid inhalation and skin/eye contact. Do not mix with acids or strong oxidizers (releases sulfur dioxide); consult the SDS for first‑aid and spill procedures.
How do concentrations and grades of sodium metabisulfite differ for food and industrial use?
Sodium metabisulfite is supplied in multiple grades (food, technical, and reagent) and in dry and solution forms; typical food‑grade purity ranges commonly from about 95–99% depending on specification. Choose grade and concentration based on regulatory requirements and the specific application.
What documentation is available when purchasing food‑grade sodium metabisulfite?
Suppliers typically provide a Safety Data Sheet (SDS), Certificate of Analysis (COA), Technical Data Sheet (TDS) and, on request, regulatory declarations such as Kosher/Halal, GMP statements, and allergen or traceability information. Always request the COA and SDS to confirm purity and compliance for your use.
How is sodium metabisulfite shipped and what packaging options are common?
It is commonly shipped in sealed 25 kg paper or plastic bags, lined drums, or bulk big bags; solutions may be shipped in IBCs. Transport requirements vary by jurisdiction, so consult the SDS and local transport regulations for any restrictions and recommended handling during shipment.
What materials and chemicals is sodium metabisulfite incompatible with, and what containers are recommended?
It is incompatible with strong acids, strong oxidizers, nitrites and halogens and can liberate sulfur dioxide on acid contact; it may also corrode certain metals like copper and brass. Store in corrosion‑resistant containers such as HDPE, polypropylene or stainless steel (316) and avoid reactive metal packaging.
What are the key technical specifications for food‑grade sodium metabisulfite?
Key specifications include CAS 7681-57-4, formula Na2S2O5, molar mass 190.10 g·mol−1, white to slightly yellow crystalline powder that is soluble in water and hygroscopic. Typical analyses specify assay/purity, moisture content and chloride/iron limits — check the supplier COA for exact values.
Which industries and specific applications commonly use food‑grade sodium metabisulfite?
Common uses include food and beverage processing (as a preservative/antioxidant and bleaching agent), winemaking, water treatment, photographic and textile processing, pulp and paper, and laboratory reducing or dechlorinating applications. Select food‑grade material when product contact with food is intended and verify regulatory compliance for your market.
How can I purchase food‑grade sodium metabisulfite and is it readily available?
Food‑grade sodium metabisulfite is widely available from chemical distributors and specialty food ingredient suppliers in various pack sizes and grades; lead times and minimum order quantities vary by supplier. When ordering, specify the required grade, pack size, request the SDS and COA, and confirm any regulatory or certification needs.

Documentation & Downloads

Request SDS
Safety Data Sheet
Request COA
Certificate of Analysis
Technical Data Sheet (TDS)
Available for all products

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