Study of antioxidant and mutagenic activity of different orange juices

The mutagenic effects of in natura and processed (fresh and frozen) orange juices were evaluated by the Salmonella/microsome assay (Ames Test). Antioxidant potential was determined by deoxyribose degradation, as well as by the nitro blue tetrazolium reduction test. The juices inhibited degradation of deoxyribose and were able to trap the superoxide anion. At concentrations up to 1% they acted as pro-oxidants in lipid peroxidation in a concentration-dependent manner. However, this activity was less effective at 10% juice concentration. The sweetened processed juice was not able to decrease peroxidation nor to trap superoxide anions. Significant correlation between total phenolics and the inhibition of deoxyribose degradation was observed; also, a significant correlation between lipid peroxidation and total phenolics was found. Vitamin C was a pro-oxidant in tests employing transition metals. Mutagenicity was observed in the Ames test, particularly for fresh, in natura, juice samples. The highest responses were observed in strains TA97a and TA98. Fresh processed juice, which had the best antioxidant potential, was not mutagenic in any of the strains tested. Positive results for mutagenesis in TA97a, with metabolization, were correlated with total phenolics and vitamin C. (C) 2004 Elsevier Ltd. All rights reserved.