Preservatives, food sodium sulfite

Dissolved in water, sulfur dioxide produces sulfurous acid (H2S03), hydrogen sulfite ion (HSOj), and sulfite ion (SOf ). Sodium sulfite (Na2S03) has been used as a chemical food preservative, although some individuals are hypersensitive to it. 

Sodium sulfite (Na2S03) is produced by reacting sulfur dioxide with a solution of sodium carbonate or sodium hydroxide. Sodium sulfite is also recovered as a byproduct of resorcinol production. About half of the sodium sulfite produced in North America is used by the pulp and paper industry (i.e., chemithermomechanical process). It is also used in photography, textile bleaching, and food preservation, and as a chemical intermediate. Some producers can switch from sodium sulfite to sodium bisulfite or metabisulfite in the same facility. In 1998, the market demand for sodium sulfite was 102,000 tons in the United States, excluding that produced and used captively by some paper mills. The demand has decreased substantially over the recent years as pulp mills have reduced sulfur discharges. 

Sodium sulfite is used as an antioxidant in applications similar to those for sodium metabisulfite It is also an effective antimicrobial preservative, particularly against fungi at low pH (0.1% w/v of sodium sulfite is used). Sodium sulfite is used in cosmetics, food products, and pharmaceutical applications such as parenteral formulations, inhalations, oral formulations, and topical preparations. 

Applications Sodium sulfite is utilized as a reducing agent, in the manufacture of sodium thiosulfate, as an oxidation-prevention agent for developer solutions in the photographic industry, as an antichlorination agent in the paper and textile industries, for the preservation of food and for the treatment of boiler water. 

Sodium sulfite is an odorless, solid white powder with a salty sulfurous taste that is soluble in water. It is a reducing agent that is used as a food preservative and antioxidant. Its use is prohibited in meats and other sources of vitamin Bj. Sodium sulfite is also used in the treatment of semichemical pulp in the paper industry, in the treatment of water, as a photographic developer, and in textile bleaching (antic-hlor). It has also found historical use in the water treatment field as a dechlorinating agent. 

Sulfur dioxide, SO2, dissolves in water and accordingly, largely removed in the upper respiratory tract. It is an irritant to the eyes, skin, mucous membranes and respiratory tract. Some individuals are hypersensitive to sodium sulfite,Na2S03, which is used as a chemical food preservative. Sulfur dioxide is especially hazardous for ecosystems due to acid rains (see Chapter 4). 

Sodium sulfite has been used as a food preservative for many years. However, in 1986 the U.S. Food and Drug Administration (FDA) banned the use of sodium sulfites for certain types of food. The agency had discovered that about one in a hundred people are sensitive to sodium sulfite. Thirteen deaths and more than 500 allergic... 

Potassium metabisulfite (potassium pyrosulfite) is used as an antifermenting agent in breweries and wineries, and to bleach straw. Sodium bisulfite (sodium acid sulfite) is mainly used in pharmaceutical products, as disinfectant or bleach, and in the dye industry. Sodium sulfite is used in photographic developers, for fixing prints, bleaching textile fibers, and as a preservative in the food industry. 

About 55% of sodium sulfite produced is used by the paper industry. Another 10% is used in oil recovery and 20% is used in photography. Sodium sulfite is used in water treatment and is a reducing agent in dye processes. Sodium sulfite is used in food preservation and in textile bleaching. 

There are different kinds of chemical preservatives commonly used in foods which either inhibit the activity of bacteria or kill the bacteria. These chemicals include benzoates (such as sodium benzoate), nitrites (such as sodium nitrite), sulfites (such as sulfur dioxide) and sorbic acid. 

Preservatives. Most preservatives do not kill microorganisms present in food. Rather, they prevent further growth and proliferation of anything that is present by either lowering the water activity or increasing the pH of the foods in which they are used. Preservatives include benzoates, sorbates. propionates, organic acids, sulfur dioxide and sulfites, parabens. sodium nitrate and sodium nitrites, and natamycin and ntsin. See also Preservative. 

Preservatives. Sulfur compounds, such as sulfur dioxide and sodium bisulfite, are used commercially to preserve the color of various food products, such as orange juice, dehydiated fruits and vegetables, such as apricots, carrots, peaches, pears, potatoes, and many odiers. Concentrated sulfur dioxide is used in wine-making to destroy certain bacteria. The color preservation of canned green beans and peas is enhanced by dipping the produce in a sulfite solution prior to canning. In 1986, some of these compounds and uses were put under closer regulation in the United States. 

Sulfites and bisulfites have been used extensively as preservatives in the food industry and also in drugs and bronchodilator inhalant solutions (1,2) as preservatives. Sodium metabisulfite is used commonly as an antioxidant in foods and drugs. As an additive in various pharmaceutical products, metabisulfite can cause unpleasant adverse reactions. 

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