Antioxidative activity Maillard reaction extracts

Antioxidative Activity of MaUlard Reaction Extracts. In the antioxidative assay system utilized in this study heptanal was readily oxidized to heptanoic acid in the dichloromethane solutions. However, the presence of a-tocopherol (Figure 1) inhibited this transformation in a concentration dependent manner. This system was then used to evaluate the antioxidative activity of dichloromethane extracts of several Maillard reaction model systems. Figure 2 shows the antioxidative activity of 5- iL aliquots of each pH extract from a microwave heated glucose/cysteine model system. The order of antioxidative effect of the extracts from the samples was as follows pH 9 > pH 5 > pH 2 > pH 7. The Maillard reaction is catalyzed under both slightly basic and acidic conditions and may explain this trend. Volatiles from sugar/cysteine Maillard reaction... 

Sato et a2- (34) demonstrated that a variety of common meat additives, inclucnrTg cottonseed flour, nonfat dry milk, spray-dried whey, wheat germ, and textured soy flour, inhibited WOF in the meat system. These products may have exerted their inhibitory effect on WOF through the Maillard reaction, since most of them contain some reducing sugars. Pratt (40) reported soybeans and soy protein concentrate had an inhibitory effect upon development of WOF and was able to demonstrate that the active components are water soluble. Fractionation and analysis of the water-soluble fraction showed the antioxidant activity was due to the presence of isoflavones and hydroxylated cinnamic acids (40). This confirms earlier work showing that the flavonoTcis present in plant extracts inhibit oxidation in sliced roast beef (41 ). 

Measurement of Antioxidative Activity. The antioxidative activity of the Maillard reaction products was evaluated by a method similar to that developed by Macku and Shibamoto (9) and later modified by Eiserich et al. 10). The antioxidative activities of 25 iiL-aliquots of peanut oil/cysteine and peanut oil/methionine dichloromethane extracts and 5 nL-aliquots of the glucose/cysteine extracts were measured. 2-Alkyl-thiophenes, 2-thiophenethiol, 2-methyl-3-furanthiol, fiirfuryl mercaptan, thiazolidine, and 1,3-dithiolane were tested for antioxidative activity at a concentration of 1 mM. The above extracts and standards were added to dichloromethane solutions containing 25 mg of heptanal. Nonadecane (400 mg) was added as a gas chromatographic internal standard, and the resulting solutions were brought to a 5-mL final volume with... 

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