The antimutagenicity of Maillard reaction products (MRPs) prepared by refluxing D-glucose and L-tryptophan under various reaction conditions was determined by means of the Ames test. The dose of MRPs with 5 mg per plate showed no toxicity, and mutagenicity to Salmonella typhimurium TA98 and TA100 was used for antimutagenic assay. The mutagenicity of 2-amino-3-methylimidazo (4,5-f) quinoline (IQ) and 2-amino-6-methyldipyrido (1,2-a:3′,2′-d) imidazole (Glu-P-1) toward TA98 was markedly reduced by the addition of glucose-tryptophan MRPs, whereas the mutagenicity of 4-nitroquinoline-N-oxide (NQNO) was not inhibited. The mutagenicity of IQ, Glu-P-1, and NQNO toward TA100 was also markedly reduced by glucose-tryptophan MRPs, but the mutagenicity of NQNO was only slightly inhibited. Greater antimutagenic effects of glucose-tryptophan MRPs were found when these materials were prepared at an alkaline pH. The optimum combinations of reaction conditions for obtaining antimutagenic MRPs to IQ were glucose-tryptophan molar ratio = 0.5:0.25 at pH 9.0 for 5 and 10 h, molar ratio = 0.5:0.5 at pH 11.0 for 10 h, and molar ratio = 1.0:0.25 at pH 7.0 for 15 h and at pH 11.0 for 15 h. The antimutagenic effect of glucose-tryptophan MRPs to IQ and Glu-P-1 was well correlated with their browning intensity, reducing power, and antioxidative activity. The antimutagenicity of glucose-tryptophan MRPs might be due to both desmutagenic and bio-antimutagenic effects.
Effect of glucose on the antioxidative activity of Maillard reaction products during extrusion cooking.
