Formation and identification of carcinogenic heterocyclic aromatic amines in boiled pork juice

Bacterial frameshift mutagens have been found in boiled pork juice. The mutagenic compounds of boiled pork juice were purified and analyzed by HPLC. The mutagenic fractions corresponding to the peaks of the standard mutagens 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) were confirmed by comparison of UV and mass spectra. One gram equivalent of original lean ground pork was estimated to contain 4.1 ng of MeIQx, 3.7 ng of IQ, and 1.2 ng of MeIQ, which accounted for 21.0%, 30.4%, and 38.1%, respectively, of the total mutagenicity. The remaining mutagenic fractions might be diMeIQx isomers. This will be further confirmed by mass spectrometry in future studies. The amount of IQ-type mutagens in boiled pork juice was about 4-fold higher than in broiled beef. Furthermore, we investigated the effects of 20 amino acids, three monosaccharides, and creatinine on mutagen formation when added to the pork juice to elucidate possible precursors leading to the formation of mutagens. Results showed that five amino acids (glutamine, tyrosine, glycine, alanine, and threonine) and two monosaccharides (ribose and glucose) might participate in mutagen formation in boiled pork juice.