Oxidation butylated hydroxyanisole

Mineral oil undergoes oxidation when exposed to heat and light. Oxidation begins with the formation of peroxides, exhibiting an induction period . Under ordinary conditions, the induction period may take months or years. However, once a trace of peroxide is formed, further oxidation is autocatalytic and proceeds very rapidly. Oxidation results in the formation of aldehydes and organic acids, which impart taste and odor. Stabilizers may be added to retard oxidation butylated hydroxyanisole, butylated hydroxytoluene, and alpha tocopherol are the most commonly used antioxidants. 

The vitamin D resin is stabilized against oxidation by the addition of < 1 wt% butylated hydroxyanisole or butylated hydroxytoluene. 

Antioxidants are not important only to the health conscious food manufacturers also rely on these chemicals to maintain the shelf life of their products. Synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and tert-butyl hydroquinone were widely used in food processing to control oxidation and maintain food quality. However, as these synthetic antioxidants are suspected to be carcinogenic they now have restricted use in food (Madahavi and Salunkhe, 1995). Therefore, natural antioxidant sources, especially of plant origin, are of great interest to the food industry. 

The antioxidants suggested by Swisher (1) were 4-methy1-2,6-ditertiary butylphenol, butylated hydroxyanisole or any other oil soluble, heat stable antioxidant. Antioxidants (0.05% of the essential oil) were considered to be necessary since the heat of the molten corn syrup might otherwise result in oxidation of the citrus oils. 

Several stabilizers are useful in minimizing oxidative degradation during thermoplastic processing or in the bulk solid. Phenothiazine, hindered phenolic antioxidants such as butylated hydroxytoluene, butylated hydroxyanisole, and secondary aromatic amines in concentrations of 0.01—0.5% based... 

Experimentally, anti-oxidants such as gallic acid, ethyl gallate, oat flour (Findlay and Smith, 1945), sorbitan monostearate, glycerol monostearate, polyoxyethylene sorbitan monostearate (Hibbs and Ashworth, 1951), ascorbyl palmitate, dodecyl gallate (Abbot, 1971), high-oryzanol rice bran oil - containing tocopherols and tocotrienols (Nanua et al, 2000), nordihy-droguaiaretic acid, butylated hydroxyanisol, butylated hydroxy toluene and citric acid (Helal et al., 1976) have been used to enhance the oxidative stability of milk powders. 

Butylated hydroxyanisole (BHA) is often added to foods as an antioxidant. It stops oxidation by reacting with radical intermediates to form a relatively stable free-radical intermediate (BHA radical). The BHA radical can react with a second free radical to form an even more stable quinone with all its electrons paired. 

Antioxidant Agent that inhibits oxidation and thus is used to prevent deterioration of preparations by oxidative process Ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, hypophosphorus acid, monothioglycerol, propyl gallate, sodium ascorbate, sodium bisulfite, sodium formaldehyde, sulfoxylate, sodium metabisulfite... 

Gum bases normally contain a permitted antioxidant. Typically, buty-lated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) or toco-pherols are used. The reason that these substances are used is that the gum base is subject to oxidation, and antioxidants work because they act as free-radical traps. Oxidation normally occurs via a free-radical mechanism, and because of this, oxidation is a zero free energy process and relatively unaffected by the ambient temperature. 

Antioxidants are used widely in fats and oils products to delay oxidative processes. Synthetic antioxidants, namely, butylated hydroxyanisole (BHA), butylated hydro-xytoluene (BHT), tert-butyUiydroquinone (TBHQ), and propyl gallate (PG), are permitted antioxidants that are frequently used in products. Their presence and concentration may be determined with HPLC and GC methods. Meanwhile, metal chelators such as citric acid may be determined by HPLC analysis. 

Autoxidation can be inhibited or retarded by adding low concentrations of chainbreaking antioxidants that interfere with either chain propagation or initiation (286). Chain-breaking antioxidants include phenolic and aromatic compounds hindered with bulky alkyl substituents. Common synthetic chain-breaking antioxidants used in food lipids include butylated hydroxyanisole (BHA), butylated hydroxyto-luene (BHT), ferf-butyUiydroquinone (TBHQ), and propyl gallate (PG). This class of antioxidants react with peroxy free radicals to terminate reaction chains. The antioxidant radical (A ) formed in Equation 5 should be relatively stable and unable to initiate or propagate the oxidation chain reaction. 

Butylated hydroxyanisole is an antioxidant (see Table I) with some antimicrobial properties. It is used in a wide range of cosmetics, foods, and pharmaceuticals. When used in foods, it is used to delay or prevent oxidative rancidity of fats and oils and to prevent loss of activity of oil-soluble vitamins. 

Butylated hydroxyanisole is phenolic and undergoes reactions characteristic of phenols. It is incompatible with oxidizing agents and ferric salts. Trace quantities of metals and exposure to light cause discoloration and loss of activity. 

Propyl gallate has become widely used as an antioxidant in cosmetics, perfumes, foods, and pharmaceuticals since its use in preventing autoxidation of oils was first described in 1943. It is primarily used, in concentrations up to 0.1% w/v, to prevent the rancidity of oils and fats it may also be used at concentrations of 0.002% w/v to prevent peroxide formation in ether, and at 0.01% w/v to prevent the oxidation of paraldehyde. Synergistic effects with other antioxidants such as butylated hydroxyanisole and butylated hydroxytoluene have been reported. Propyl gallate is also said to possess some antimicrobial properties see Section 10. 

Lipid oxidation. Lipid oxidation is normally observed as a product discoloration and can be exacerbated with excess levels of bleach. It is catalyzed by metal ions, enzymes, and pigments. Acidic compounds can be used to complex the metal ions. Synthetic antioxidants, such as butylated hydroxtoluene (BHT) and butylated hydroxyanisole (BHA) can be added to the product, but are limited and coming under increased scrutiny due to toxicology concerns. It may be preferable to use natural antioxidants such as lecithin or vitamin E or to dry under vacuum or in an inert (nitrogen, steam) atmosphere. 

Antioxidants are frequently added to unsaturated fats and oils in order to protect these against oxidative deterioration. For this reason, they are also added to a variety of food products containing unsaturated lipids. Antioxidants frequently applied are esters of gallic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene... 

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