Sulfur dioxide antioxidants

In kaolin (clay) processing, sulfur dioxide reduces colored impurities, eg, iron compounds. In the bromine industry, sulfur dioxide is used as an antioxidant in spent brine to be reinjected underground. In agriculture, especially in California, sulfur dioxide is used to increase water penetration and the avadabiHty of soil nutrients by virtue of its abiHty to acidulate saline—alkaH soils (327). It is also usefiil for cleaning ferric and manganese oxide deposits from tile drains (328). 

Sulfur dioxide, sulfites, and metabisulfites have had extensive use as antimicrobial preservatives in the food industry. In pharmaceuticals they have had a dual role, acting as preservatives and antioxidants. The sulfa dmgs, or sulfonamides, the first effective chemotherapeutic agents to be employed... 

Salts of sulfur dioxide, including bisulfite, metasulfite, and sulfite, are the most common antioxidants used in aqueous parenterals. These antioxidants maintain product stability by being preferentially oxidized and... 

Sulfur dioxide is used widely in the wine industry as a sanitizing agent and antioxidant (46,47,48). In the pH range of 3.0 to 5.0, a slight decrease in pH increases the antiseptic action of sulfur dioxide (49, 50, 51). 

Sulfur Dioxide and Aldehydes. Sulfur dioxide is commonly added both before and after fermentation in preparing white table wines. It is an effective antioxidant as well as a selective inhibitor of unwanted microorganisms. However, sulfur dioxide, as the bisulfite ion in solution, combines with aldehydes, especially acetaldehyde, during fermentation giving an accumulation of aldehydes in the bound form of aldehyde-sulfurous acid. 

The must is subsequently sterilized, boiling being the most commonly used method (McConnell and Schramm, 1995 Navratil et al., 2001 Ukpabi, 2006). Heat treatments also have the potential to alter the antioxidant capacity by changing their phenolic profiles (Wintersteen et al., 2005). However, other techniques are described in the literature. These include the use of metabisulfite (sodium or potassium salts or in commercial form as Campden tablets)—releases sulfur dioxide that either kills or inactivates most microbes (McConnell and Schramm, 1995 Roldan et al., 2011), sulfur dioxide gas (Pereira et al., 2009 Ukpabi, 2006), pasteurization (McConnell and Schramm, 1995 Mendes-Ferreira et al., 2010), and ultrafiltration, with a 50-kDa molecular weight cutoff (McConnell and Schramm, 1995). Some of these methods also promote the removal of proteins by denaturation and coagulation, resulting in more rapid clarification during maturation. 

Chemical preservatives include free radical scavengers (also known as antioxidants), such as vitamin C and compounds such as BHA (butylated hydroxyanisole), and bacterial growth inhibitors, such as benzoic acid, sulfur dioxide, and sodium nitrite (NaN02). Ethanol (CH3CH2OH) has long been used as a preservative, both of itself (as in wine), and of other foods (e.g., fruits stored in brandy). Some chemical preservatives may be harmful Sulfur dioxide (often used to preserve wines) is irritating to the bronchial tubes of persons who have asthma, and nitrites have been implicated as carcinogens. 

Sulfur dioxide and sulfites have long been used as preservatives, serving both as antimicrobial substance and as antioxidant. Their use as preservatives in wine dates back to Roman times. Sulfur dioxide is a gas that can be used in compressed form in cylinders. It is liquid under pressure of 3.4 atm and can be injected directly in liquids. It can also be used to prepare solutions in ice cold water. It dissolves to form sulfurous acid. Instead of sulfur dioxide solutions, a number of sulfites can be used (Table 11-2) because, when dissolved in water, they all yield active S02. 

Perhaps the most common use of inhibitors is as preservatives for the food and cosmetics industry on labels they are often called antioxidants, i.e. they prevent the oxidation of certain substances in the food or cosmetic, keeping it fresh for longer. For example, sulfur dioxide preserves dried fruit, peas and beans. 

Certain enzymes present in grapes are responsible for wine problems such as clouding, darkening or an oxidized taste. To prevent this, wineries routinely treat must and wines with sulfur dioxide. In addition to its antimicrobial activity, SO2 has an antioxidative property which prevents browning and taste defects. Polyphenoloxidase has detrimental effects on wine quality. However enzymes are also responsable for the formation of certain desir able esters which are essential to the aroma or bouquet of the wine. 

GuMusLii S, Akbas H, Aliciguzel Y, Agar A, Kucukatay V and Yargicoglu P (1998) Effects of sulfur dioxide inhalation on antioxidant enzyme activities in rat erythrocytes. Indian Health 36 70— 73. 

Yargicoglu P, Agar a, Gumuslu S, Bilmen S and Oguz Y (1999) Age-related alterations in antioxidant enzymes, lipid peroxide levels, and somatosen-sory-evoked potentials effect of sulfur dioxide. Arch Environ Contam Toxicol 37 554-560. 

It is well established that reactions involving oxygen dissolved during handling operations carried out in contact with air are generally slow. These reactions are catalyzed by iron and copper ions. Sulfur dioxide acts as an irreversible antioxidant. It has been shown (Ribereau-Gayon et al., 1976) that a free SO2 concentration of around 100 mg/1 is necessary to provide full protection,... 

Sulfoxides themselves yield, on further oxidation, even more powerful hydroperoxide decomposers than the original sulfides, in that they are able to destroy several equivalents of hydroperoxides. This catalytic effect is explained by the intermediate occurrence of sulfenic acids and sulfur dioxide. The fact that the phenomenon of synergism, which is defined as a cooperative action such that the total effect is greater than the sum of two or more individual effects taken independently, is often observed when primary and secondary antioxidants are combined ahs been explained with the concept of the simultaneous occurrence of the radical reactions (e.g.. Equation 1.72) and the nonradical hydroperoxide decomposition (e.g.. Equation 1.74 and Equation 1.75). 

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