Mutagenic responses of freshly squeezed orange juice, fresh orange juice heated for 0.5-30 min at 100 °C, and several commercial orange juices were investigated in four bacterial strains of Salmonella typhimurium (TA98, TA100, TA102, TA2637) with and without microsomal activation. The response without activation was similar in all cases, ranging 2-3 times the background values. The experiments with microsomal activation produced barely visible pinpoint colonies that do not appear to be normal revertants. Our results do not duplicate previously reported high mutagenic activity of fresh orange juice after heating, or of commercial varieties. In preliminary studies, no increase in the number of revertants was apparent after freshly prepared apple, grape, and pear juices were heated. The possible chemical basis for the mutagenic and antimutagenic activities of fruit juices is discussed. © 1990, American Chemical Society. All rights reserved.
