Butylated hydroquinone 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. 

Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), ascorbyl palmitate, and tertiary-butyl-hydroquinone (TBHQ), are used in soybean cooking oils and frying fats (230). These antioxidants are typically added at 0.01% for one antioxidant and 0.02% total for two or more. Natural antioxidants, derived from sage, rosemary, and green tea, are increasingly popular because of consumer preferences for natural food ingredients (231). 

This sequence of reactions is affected by prooxidants and by anti-oxidants. The former-frequently metals or radical-producing species-encourage initiation whilst anti-oxidants usually shorten the propagation sequence by promoting the termination reactions. Other compounds (synergists), added to anti-oxidants to enhance their activity, are mainly metal-chelating compounds such as citric acid, phosphoric acid, ascorbic acid or ethylenediamine tetra-acetic acid which inhibit the metal-catalysed initiation. Anti-oxidants include natural compounds like the tocopherols or synthetic materials such as butylated hydroxy-anisole (BHA), butylated hydroxytoluene (BHT), propyl gallate or tertiary butyl hydroquinone. 

From Frankel et al. (1987). Abbreviations BHA, butylated hydroxyanisole, BHT, butylated hydroxytoluene, TBHQ, fert-butyl hydroquinone. 

Tert-butyl hydroxyanisole (BHA), tert-butyl hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and propyl gallate (PG) are the most common synthetic phenolic... 

Resveratrol has also been reported to offer protection against cardiovascular disease, such as coronary heart disease. The effects of resveratrol on factors implicated in the development of coronary heart disease - human platelet aggregation and the synthesis of eicosanoids (lipids) from arachidonate by platelets - were investigated and compared with the actions of other wine phenolics - catechin (1.39), epicatechin (7.18a), and quercetin (1.43) - and the antioxidants a-tocopherol (7.10a), hydroquinone and butylated hydroxytoluene. Resveratrol and quercetin demonstrated a dose-dependent inhibition of platelet aggregation, whereas the other compounds tested were inactive. Resveratrol also inhibited the synthesis of the eicosanoids in a dose-dependent manner, whereas the other phenolics were less effective of not effective at all. Removal of the alcohol from the wine did not diminish the effect on platelet aggregation (Pace-Asciak et al., 1995 Goldberg et al., 1995). 

THF is available unstabilized, or stabilized with 25 ppm (typical for GC use) to 250 ppm (typical for HPLC use) butylated hydroxytoluene (BHT 2,6-di-r-butyl-p-cresol), which is added to scavenge the peroxide breakdown products of THF. Ethyl ether can be purchased unstabilized or stabilized with ethanol ( 2-3%), BHT (1-10 ppm), or a blend of ethanol, water, and BHT (1.5-3.5%, 0.2-0.5%, and 5-10 ppm, respectively). Isopropyl ether is available unstabilized or stabilized widi 0.01% hydroquinone or 5-100 ppm BHT. Dioxane is available unpreserved or with 25-1500 ppm BHT as preservative. From the above, it is important that the correct solvent be chosen for use, since most are available unstabilized or stabilized and with a range of stabilizers and stabilizer concentrations. 

Polyethers, poly(alkylene oxides), generally must be stabilized toward oxidation. Antioxidants such as catechol, t-butyl hydroxytoluene, or monoethers of hydroquinone are added (163). Phenothiazine is often used to stabilize against ultraviolet degradation, and various alkanolamines are used as thermal stabilizers (164, 165). 

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