Changes in Carcinogenic Heterocyclic Amines during in vitro Digestion

The high amounts of heterocyclic amines (HCAs) in overcooked foods are known carcinogens. However, the quantitative changes in carcinogenic substances, such as HCAs, caused by human digestion, have not been studied. This study was performed to evaluate the effects of digestive enzymes and the enterobacteria, Escherichia coli (E. coli) and Lactobacillus casei (L. casei), on the quantitative changes in four HCAs: 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Digestive enzymes gradually reduced the amount of four HCAs during in vitro experiments (p < 0.05). The concentration of all HCAs rapidly decreased after digestion in the mouth and stomach. L. casei dramatically reduced the amount of HCAs during in vitro digestion (p < 0.05). From the results of this study, we hypothesize that the amount of HCAs in overcooked food could be decreased, and their risk could be reduced during human digestion by digestive enzymes and enterobacteria.