Two types of Sodium Metabisulfite in Sante

2019-10-08

Sodium metabisulfite is a white or yellow crystalline powder or a small crystal. The molecular formula Na2S2O5 has a strong sulfur dioxide odor and a specific gravity of 1.4. It is soluble in water and acidic in aqueous solution. When exposed to a strong acid, it releases sulfur dioxide to form the corresponding salt. Exposure to air for a long time is easily oxidized to Na2S2O6. Therefore, the product cannot be used forever. Above 150 degrees Celsius, sulfur dioxide is decomposed. Sodium metabisulfite is a food additive widely used in the food industry. The key to its action is the formation of sulfites. Sulfite is a strong reducing agent. It can reduce pigmentation and fading during oxidation, keep food bright, inhibit oxidase in food, and prevent food from spoiling. In addition, it can be blocked due to its reduction. The normal physiological oxidation process of microorganisms inhibits the reproduction of microorganisms and thus serves as a preservation. Therefore, sodium metabisulfite is a commonly used bleaching agent and preservative in the processing of agricultural products.


     Sodium metabisulfite can be divided into industrial grade and food grade, and its quality indicators are different. Industrial sodium metabisulfite is mainly used in the chemical, pharmaceutical, rubber, leather, printing and dyeing and photographic industries. Food grade sodium metabisulfite is used in the food industry. In the food industry, additives are often added to foods in order to improve the color, aroma, taste and quality of the food, as well as the need for preservation, preservation and processing techniques. Sodium metabisulfite is a food additive commonly used as a preservative, antioxidant and preservative in food processing. However, sodium metabisulfite has a certain toxicity due to residual sulfur dioxide. In mice, the median lethal dose (calculated as sulfur dioxide) is 600-700 mg/kg bw, even a carcinogen. Therefore, all countries in the world have strictly controlled it and formulated clear standards for its use, including the scope and quantity of use.


     Sodium metabisulfite is bleached by reducing the pigment. The color of most organic compounds is produced by chromophores in the molecule. All chromophores contain unsaturated bonds. The hydrogen atoms released by the reducing bleach can cause the unsaturated bonds in the chromophore to become single bonds, causing the organics to lose color. The browning of some foods is caused by the presence of ferric ions. The reducing bleach can convert ferric ions into divalent iron ions to prevent food browning. The sulfite addition reaction bleaches sodium metabisulfite. The addition reaction of anthocyanins and sugars can be bleached and discolored. The reaction is reversible. Sulfite can be removed by heating or acidification, which can regenerate anthocyanins and restore the original red color.


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