| Abstract: | In last year project, we have been found five amino acids (glutamine, tyrosine, glycine, alanine, and thronine) and two monosaccharides (ribose and glucose) might participate in mutagen formation in boiled pork juice. To study the mutagen formation in boiled pork juice, these active precursors were used to establish the amino/ribose/creatinine aqueous model. The mutagenic compounds produced from the model systems of three active amino acids alone or combined (glutamate, glycine, and alanine) conditions were purified by acid-basic partition and blue-cotton extraction, and were finally analyzed by HPLC. The optimal reaction conditions of each model system for the mutagen formation, the molar ratio of the three reactants and the boiling period, were first evaluated. The mutagenicity of basic extracts of their reaction mixtures were examined with S. typhimurium TA98 in the presence of S9 mix. The results showed that 2:1:1, 1:1:1, 2:1:3 were the optimal molar ratio of the three reactants for ARC, AsRC, and GRC models respectively. To confirm whether the optimal molar ratio for each model to be correct or not, the consumptive amounts of the three reactants after heating were analyzed by HPLC. The highest consumptive amounts of the three reactants were observed with the optimal molar ratio of each model. It indicated that the complete reaction for the mutagen formation was occurred in the optimal molar ratio of the three reactants. The major mutagenic compounds of various model systems were further purified and analyzed by HPLC. Our results showed that MeIQx, IQ, MeIQ, 4,8-DiMeIQx, and Glu-P-1 were detected to be one to three mutagens from a alanine, aspartate, glutamate/ribose/creatinine model system, respectively. The mutagenic fraction with retention time of 15 min exhibited more or about equal a half of total mutagenicity in GRC, MRC, and AsRC models, while 4,8-DiMeIQx was the major mutagenic compound in ARC model. The major mutagenic contributor of three model systems (AsRC, GRC, and MRC) did not correspond to the known cooked-food mutagens. Therefore, the mutagen formation in boiled pork juice might not seem to be modeled by these simple model system. |
