title: Formation of carcinogenic 4(5)-methylimidazole in Maillard reaction systems.
abstract: 4(5)-Methylimidazole has received the attention of federal and state regulatory agencies because of its carcinogenicity and common presence in foods and beverages. In the present study, the formation of 4(5)-methylimidazole in Maillard reaction model systems consisting of D-glucose/NH(3), L-rhamnose/NH(3), methylglyoxal/NH(3), and methylglyoxal/formaldehyde/NH(3) was investigated. 4(5)-Methylimidazole was formed at levels ranging from 0.49 to 0.71 mg/mL in the d-glucose/NH(3) model system. The formation of 4(5)-methylimidazole was slightly higher in the L-rhamnose/NH(3) system (0.91 mg/mL) than in the d-glucose/NH(3) system (0.71 mg/mL) under the conditions used in the present study. A methylglyoxal/NH(3) system produced significantly higher levels of 4(5)-methylimidazole (5.70 mg/mL), suggesting that methylglyoxal is an important precursor of 4(5)-methylimidazole. Ammonolysis of methylglyoxal, which is one of the glucose degradation products, was proposed to form formamide, which subsequently reacted with 2-aminopropanal (α-aminocarbonyl intermediate) formed from methylglyoxal to give 4- or 5-methylimidazole. The levels of 4(5)-methylimidazole found in commercial cola soft drinks range from 0.30 μg/mL (brand 3) to 0.36 μg/mL (brands 1 and 5).
authors.affiliation: Department of Environmental Toxicology, University of California, Davis, California 95616, United States.
authors.forename: Joon-Kwan
authors.initials: JK
authors.lastname: Moon
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shibamoto
mesh_terms: D001628:Beverages / Q000032:analysis; D002273:Carcinogens / Q000737:chemistry*; D005503:Food Additives / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D015416:Maillard Reaction
chemical_list: D002273:Carcinogens; D005503:Food Additives; D007093:Imidazoles; C023439:4-methylimidazole