BHA and BHT

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are used in foods and topical preparations. Meneghini et al. (1971) found 1 of 360 consecutive patients positive to patch test with BHA and negative to BHT. BHA sensitivity from a miconazole nitrate cream containing 0.005% BHA has been reported (De-GREEF and Verhoeve 1975). Roed-Petersen and Hjorth (1976) described 2 of 112 patients positive to BHA and/or BHT. Both had flares of dermatitis after an oral challenge. 

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BHA and BHT, which are both fat soluble, are effective ia protecting animal fat from oxidation, and are often added duting the rendering process. Propyl gallate is also effective, but it has limited fat solubiUty, and turns bluish black ia the presence of iron. It is typically used as a synergist ia combination with BHA or BHT. TBHQ is most effective against oxidation ia polyunsaturated vegetable oils (qv), and is often used ia soybean oil (19). 

When a combination of gallates, BHA and BHT are used, the individual levels must be reduced proportionally... 

Due to the popularity of THF as an eluent for GPC, this sort of "differential solvation" must be kept in mind, particularly when polar solutes are analyzed. This effect can also work against resolution in SMGPC, as demonstrated in Figure 1. Here BHA and BHT are fully resolved in CHCI3 but coelute in THF. Both BHA and BHT have phenolic sites, but the site on BHT is sterically hindered and apparently does not form a hydrogen bond with THF. The hydrogen bonded BHA/THF complex which does form... 

Figure 1. Separation of BHA and BHT on a lOOA Ultrastyragel column using chloroform and tetrahydrofuran. Conditions ...

Antioxidant-Treated Beef Patties. The effect of several primary antioxidants, PG, TBHQ, Tenox 20 (which contains TBHQ and citric acid) and Tenox 4A (which contains BHA and BHT) were also evaluated by instrumental, chemical and sensory methods for their effectiveness in raw/stored and cooked/stored beef, see Tables 1-4. These particular antioxidants were chosen based on their antioxidant effects on MFD as determined previously (14) and because of their GRAS status. Experimental samples were prepared similarly to those of the 0-and 2-day controls, except the antioxidants, either dissolved or suspended in water, were mixed into the raw ground meat. 

A procedure for extracting BHA and BHT from vegetable oils has been reported by Phipps (98). The oil was dissolved in n-heptane and extracted with dimethylsulphoxide (DMSO). Extracts of DMSO were mixed with aqueous sodium chloride solution, and the SPA were back-extracted into petroleum ether with subsequent concentration and analysis. 

Butylated hydroxytoluene, BHT loophole. BHA and BHT can also leach into products from cereal wrappers and clingfilm. 

Wade et al. (1986) reported that BHA and BHT were effective in retarding oxidation of anhydrous milk fat but DL-a-tocopherol acted as a pro-oxidant. Natural antioxidants in betel and curry leaves have also been reported to retard oxidation of anhydrous milk fat (Sharma, 1981 Parmer and Sharma, 1986). Amr (1991) reported that turmeric and wheat grits were as effective as BHA and BHT in controlling oxidative rancidity in sheep s anhydrous milk fat for up to 4 months. However, rosemary, sage, rue and fennel exerted pro-oxidant effects. Quercetin and rutin are reported to be efficient antioxidants in butter (Eriksson, 1987). 

The antioxidants BHA and BHT are commonly used as food preservatives. Show how BHA and BHT can be made from phenol and hydroquinone. 

The antioxidants butylated hydroxyanisole (BHA), butylated hydroxytolu-ene (BHT), tm-butylhydroquinone (TBHQ), propyl gallate, ascorbyl palmitate and citric acid were evaluated for potential to reduce NOx emissions from a single cylinder, direct-injection, air-cooled, naturally aspirated Yanmar engine (Hess et al, 2005). BHA and BHT reduced NOx emissions by 4.4 and 2.9%, respectively, but the other antioxidants evaluated did not exhibit any beneficial effects (see Table 1.2). Antioxidants may impede NOx formation by inhibiting the formation of combustion-derived radicals. 

Butylated Hydroxytoluene (BHT) BHT is also a monohydroxyphenol (Figure 4) and is widely used in foods. This fat-soluble antioxidant is available as a white crystalline compound. BHA is less stable than BHT at high temperatures and has lower carry-through properties. BHA and BHT act synergistically, and several commercial antioxidant formulations contain both of these antioxidants. BHT is effectively used in oxidation retardation of animal fats. It is postulated that BHA... 

Phenolic and polyphenolic compounds are the most active dietary antioxidants (14). The structural variation of phenolic antioxidants directly influences their physical properties, resulting in differences in their antioxidant activity. BHA and BHT are examples of phenols, in which the aromatic ring contains alkyl groups (hindered phenols), which are extremely effective as antioxidants (11). 

The daily dietary intakes of BHA and BHT have been estimated in many countries. The daily intakes of BHA and BHT in Japan in 1998 were 0.119 and 0.109 mg/d/person, which reflect 0.5% and 0.7% of the acceptable daily intake (ADI), respectively (35). The estimates of theoretical maximum daily intake (TMDl) of BHA and BHT in Brazil published in 2001 were in the range of... 

Salad and cooking oils have varying amounts of natural antioxidants, mostly toco-pherols. With the introduction of synthetic antioxidants, it has been customary to supplement the natural antioxidants with the synthetic ones. Most commonly used synthetic antioxidants are butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), propyl gallate (PG), ascorbyl palmitate, and tertiary butyl hydro-quinone (TBHQ). As a result of the questionable health implications of BHA and BHT, use of BHA and BHT is becoming rare. In recent times, TBHQ, because of its superior performance, has been used more extensively than the other synthetic antioxidants. Application and status of antioxidants have been reviewed (75). 

Antioxidants added before rendering improve the fat stability. Sims and Hilfman (42) studied the stabilization of lard and edible beef fats during pressure steam rendering. Antioxidants tested included butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate and citric acid combinations, and a mixmre of BHA and BHT. Best results for a given stabihzer level were obtained with the individual phenolics BHA and BHT. Poorer results were obtained with the mixtures in propylene glycol. 

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