Propyl gallate , effect

Antioxidants (qv) have a positive effect on oils when present in the proper concentration. Sterols and tocopherols, which are natural antioxidants, may be analy2ed by gas-Hquid chromatography (glc), high performance Hquid chromatography (hplc), or thin-layer chromatography (tic). Synthetic antioxidants maybe added by processors to improve the performance or shelf life of products. These compounds include butylatedhydroxyanisole (BHA), butylated hydroxytoluene (BHT), / fZ-butyUiydroquinone (TBHQ), and propyl gallate. These materials may likewise be analy2ed by glc, hplc, or tic. Citric acid (qv), which functions as a metal chelator, may also be deterrnined by glc. 

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). 

Table 1. Effect of propyl gallate on stored raw and cooked beef patties (N=3)...

Another contributor of MFD is the presence of molecular oxygen. An initial study determined the optimum level of free radical scavenger and chelator required to prevent MFD when added to a meat sample under vacuum 38), Based on those results, subsequent experiments were designed to investigate the synergistic effects of the two compounds, propyl gallate and EDTA (tetrasodium salt), on MFD both in the presence or absence of oxygen. 

Table 6. Effect of propyl gallate (50 ppm) and EDTA (100 ppm) with and without vacuum on chemical and sensory properties of cooked beef patties stored 3 days at 4 C...

Propyl gallate Antioxidant (approved for use in oral concentrate), antimicrobial activity Prevents autoxidation of oils and peroxide formation in ether. Synergistic effects with other antioxidants such as butylated hydroxyanisole... 

Butylatedhydroxyamsole (BHA) was first used in food products in 1940. This continues as one of the commonly used antioxidants, sometimes in combination with butylated hydroxytoluene (BHT), propyl gallate, citric, or phosphoric acids, to obtain a synergistic effect. In foodcontact surfaces. BHT has been used by itself or in combination with thiodipropionates and/or phosphoric acids, to obtain a synergistic effect. Well over 50 million of antioxidants are produced per year commercially in the United Slates alone. 

Deeble DJ, von Sonntag C (1992) Decarboxylation of 3,4-dihydroxymandelic acid induced by the superoxide radical anion a chain reaction. Int J Radiat Biol 62 105 Deeble DJ, Parsons BJ, Phillips GO (1987) Evidence for the addition of the superoxide anion to the anti- oxidant -propyl gallate in aqueous solution. Free Rad Res Commun 2 351-358 Deeble DJ, Parsons BJ, Phillips GO, Schuchmann H-P, von Sonntag C (1988) Superoxide radical reactions in aqueous solutions of pyrogallol and n-propyl gallate the involvement of phenoxyl radicals. A pulse radiolysis study. Int J Radiat Biol 54 179-193 Denisov ET, Denisova TG (1993) The polar effect in the reaction of alkoxy and peroxy radicals with alcohols. Kinet Catal 34 738-744... 

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. 

The formulator needs to know the properties of each antioxidant. For example, most of the antioxidants are easily distilled by heat or steam. Propyl gallate will form strong purple complexes with iron. The preservative effects of antioxidants also can be enhanced by addition of metal chelating agents like citric acid. Furthermore, many crude feedstuffs of plant origin, including soybean meal, crude soybean oil, and lecithin, contain a variety of natural quinone-type compounds with beneficial antioxidant properties that do not require labeling. 

Some antioxidants possess antimicrobial properties, such as propyl gallate and butylated hydroxy anisole, which are somewhat effective against bacteria. Butylated hydroxy toluene has demonstrated some antiviral activity. Compatibility of antioxidants with the drug, packaging system and the body should be studied carefully. For example, tocopherols may be absorbed onto plastics ascorbic acid is incompatible with alkalis, heavy metals, and oxidizing materials such as phenylephrine, and sodium nitrite and propyl gallate forms complexes with metal ions such as sodium, potassium and iron. 

If stored at warm temperatures, glyceryl monostearate increases in acid value upon aging owing to the saponification of the ester with trace amounts of water. Effective antioxidants may be added, such as butylated hydroxytoluene and propyl gallate. 

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. 

Tayama S, Nakagawa Y. Cytogenetic effects of propyl gallate in CHO-Kl cells. Mutat Res 2001 498(1-2) 117-127. 

Sciuto AM and Moran TS (2001). Effect of dietary treatment with u-propyl gallate or vitamin E on the survival of mice exposed to phosgene. J Appl Toxicol, 21, 33-39. 

---