Sodium Metabisulphite (chemical formula: Na2S2O5, CAS number: 7681-57-4) is an inorganic compound belonging to the sulfite family, characterized by strong reducibility, good solubility, and cost-effectiveness. It appears as white crystalline powder or small crystals, with a strong pungent odor of sulfur dioxide (SO₂), and is widely used in food, industry, medicine, and other fields. This article will focus on the main types of Sodium Metabisulphite and their detailed application scenarios, combining professional technical parameters and practical application cases to provide a comprehensive introduction.
Main Types of Sodium Metabisulphite
Sodium Metabisulphite is mainly classified into three categories according to its purity, quality standards, and application fields: food grade, industrial grade, and reagent grade. Each type has distinct quality requirements and scope of application, which are strictly distinguished to ensure safety and effectiveness in use.
1. Food Grade Sodium Metabisulphite
This type of Sodium Metabisulphite complies with the national standard GB 1886.7-2015, with strict requirements on purity and impurity content to ensure food safety. Its main characteristics include: purity ≥ 96.0%, extremely low heavy metal content (lead ≤ 1mg/kg, arsenic ≤ 1mg/kg), no harmful microorganisms, and the residual amount of SO₂ must meet the requirements of food additives. The production process has high standards, requiring strict control of raw materials, production equipment, and processing environment to avoid contamination.
It is mainly used in food processing, and its use is strictly regulated by national standards to prevent excessive residues from endangering human health. The packaging is usually food-grade PE inner membrane + woven bag, with specifications of 25kg/bag, 50kg/bag, or 1kg/bottle for small-scale use.
2. Industrial Grade Sodium Metabisulphite
Industrial grade Sodium Metabisulphite implements the national standard HG/T 2826-2018, with relatively loose requirements on impurity content compared with food grade. Its main characteristics are: purity ≥ 95.0%, allowing a certain amount of impurities such as iron and moisture, and no need to meet food-grade safety indicators. The production process focuses more on production efficiency and cost control, and the raw material selection and processing precision are lower than those of food grade.
It is widely used in industrial production fields such as printing and dyeing, papermaking, and water treatment. The packaging is mostly moisture-proof woven bags, with specifications of 25kg/bag, 50kg/bag, or 1000kg/ton bag to meet the needs of large-scale industrial use.
3. Reagent Grade Sodium Metabisulphite
Reagent grade Sodium Metabisulphite complies with the national standard GB/T 637-2006, with the highest purity requirement among the three types. Its main characteristics are: purity ≥ 98.0%, extremely low impurity content, and stable chemical properties, which can meet the precision requirements of laboratory experiments. The production process is highly refined, and each link is strictly controlled to ensure the accuracy and reliability of experimental results.
It is mainly used in laboratory analysis, chemical synthesis, and biological research. The packaging is usually glass or HDPE bottles, with specifications of 500g/bottle or 2.5kg/bottle, which is convenient for laboratory storage and use.
Key Applications of Sodium Metabisulphite
Due to its strong icon-reducibility, bleaching property, and antiseptic effect, Sodium Metabisulphite has a wide range of applications in various fields. Different types of Sodium Metabisulphite are used in corresponding fields according to their quality characteristics, and the specific applications are as follows:
1. Food Industry (Main Application Field of Food Grade)
Food grade Sodium Metabisulphite is widely used as a bleaching agent, preservative, and antioxidant in food processing, which can improve food quality and extend shelf life:
- Bleaching agent: Used in preserved fruits, dried fruits, vegetable products, vermicelli, flour, and starch. It destroys the structure of pigments by releasing SO₂, achieving the effect of decolorization and brightening, making the food color uniform and transparent.
- Preservative and antioxidant: Inhibits the growth of molds, yeasts, and bacteria, extending the shelf life of food. At the same time, it can prevent the oxidation of fats and the degradation of vitamin C in food, maintaining the flavor and color of products such as wine, fruit juice, and biscuits. For example, in wine brewing, it can inhibit the growth of wild yeast and bacteria, preventing wine spoilage.
- Acidity regulator: Adjusts the acidity of the food system, improves taste, and assists in stabilizing food texture. For example, in beer brewing, it adjusts the pH value to improve fermentation stability.
It should be noted that the residual amount of SO₂ in food must comply with national standards (e.g., ≤ 0.35g/kg for preserved fruits, ≤ 0.25g/L for wine), and excessive use is strictly prohibited.
2. Industrial Field (Main Application Field of Industrial Grade)
Industrial grade Sodium Metabisulphite is widely used in industrial production due to its reducibility and bleaching property, involving printing and dyeing, papermaking, water treatment, and other fields:
- Printing and dyeing industry: Used as a bleaching agent and dechlorinating agent for cotton, linen, chemical fiber, and other fabrics. It removes residual chlorine on fabrics to avoid fiber damage and improves the uniformity of dyeing. It can also be used for reduction decolorization of dyes and stripping of dyed textiles when combined with sodium borohydride.
- Papermaking industry: Used in pulp bleaching and deinking processes, replacing some highly polluting bleaching agents, reducing the pressure of wastewater treatment, and improving the whiteness of pulp and paper.
- Water treatment field: Used as a reducing agent to remove residual chlorine (Cl₂) in drinking water and industrial wastewater, avoiding the impact of residual chlorine on subsequent treatment processes or the environment. It can also reduce heavy metal ions in wastewater, making them precipitate and be removed.
- Other industrial applications: Used as an additive in electroplating solution to prevent oxidation of metal ions; used as an anti-aging agent in the rubber industry to extend the service life of rubber products; used as a reducing agent in chemical synthesis to participate in organic reactions; used in the treatment of gold and silver leaching tailings to detoxify and recover valuable metals such as gold, silver, copper, and lead.
3. Laboratory and Scientific Research Field (Main Application Field of Reagent Grade)
Reagent grade Sodium Metabisulphite is mainly used in laboratory scenarios, relying on its high purity and stability to ensure the accuracy of experimental results:
- Chemical analysis: Used as a reducing agent to calibrate the concentration of oxidants (such as potassium permanganate) and ensure the accuracy of analysis results.
- Biological research: Used for the preservation of biological samples, the preparation of competent Escherichia coli, and the transformation of plasmid DNA or high-molecular-weight genomic DNA of eukaryotic cells. It can also stabilize enzymes and promote protein crystallization.
- Small-scale organic synthesis: Used as a reducing agent in small-scale organic synthesis reactions to promote the progress of reactions and improve product purity.
4. Other Application Fields
In addition to the above fields, Sodium Metabisulphite also has a variety of other uses:
- Medical field: Used as an intermediate in the production of antibiotics, antipyretic and analgesic drugs, and vitamins; used as an antioxidant in injections and oral liquids to prevent the oxidation of active ingredients and maintain the stability and effectiveness of drugs. It can also be used as an alternative electrolyte to relieve dehydration symptoms.
- Agriculture and aquaculture: Used as a fungicide and preservative to prevent the growth of mold and bacteria during the storage of fruits and vegetables, extending their shelf life. In aquaculture, it can increase water hardness and provide calcium ions needed for aquatic organisms (such as shellfish and crustaceans) to form shells.
- Photography industry: Used as a developer and fixer in black-and-white photo development. It can reduce exposed silver salts to form black silver particles, showing the image of the photo, and dissolve unexposed silver salts to fix the image.
- Leather industry: Used as a tanning agent or auxiliary tanning agent to denature proteins in leather, making it softer and tougher, and improving the tanning effect.
In general, Sodium Metabisulphite is divided into food grade, industrial grade, and reagent grade according to its application fields and quality requirements, each with clear positioning and scope of use. With its excellent reducibility, bleaching property, and antiseptic effect, it plays an irreplaceable role in food processing, industrial production, laboratory research, and other fields. However, it should be noted that Sodium Metabisulphite needs to be stored in a cool, dry, and well-ventilated environment, sealed tightly to avoid moisture absorption and oxidation. In the process of use, corresponding safety protection measures should be taken to ensure operational safety. With the continuous development of industry and science and technology, its application fields will be further expanded, and its market demand will also maintain a stable growth trend.
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Post time: Apr-05-2026