Formation of genotoxic 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) and its kinetics in a model system

The influence of important precursors (amino acids and sugars) and heating conditions on the formation of 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), an abundant heterocyclic amine compound, and its formation kinetics were evaluated in a chemical model system. Phenylalanine containing α-amino propenoic acid (NH₂CH₂CHCOOH) may be involved in PhIP formation whereas glycine is not. Adding different amounts of 4 sugars (glucose, galactose, fructose, and ribose) resulted in significant differences (p<0. 05) in PhIP formation in the model system. All sugars used may have been a limiting factor for PhIP formation. The formation of PhIP increased with increasing time and heating temperature and was correlated with browning reaction intensity. The rate constant of PhIP formation also increased with increasing temperature. Based on the values of activation energy, enthalpy, and activation entropy, PhIP formation was assumed to be a temperature-sensitive, endothermic, and bimolecular reaction. The results offer meaningful information for controlling the risk of PhIP formation in cooked foods.