title: Formation of 4(5)-Methylimidazole in Aqueous d-Glucose-Amino Acids Model System.
abstract: The International Agency for Research on Cancer (IRAC) has classified 4(5)-methylimidazole (4-MeI) as a group 2B possible human carcinogen. Thus, how 4-MeI forms in a D-glucose (Glu) amino acids (AA) model system is important, as it is how browning is affected. An aqueous solution of Glu was mixed individually in equimolar amounts at 3 concentrations (0.05, 0.1, and 0.15 M) with aqueous solutions of L-Alanine (Ala), L-Arginine (Arg), Glycine (Gly), L-Lysine (Lys), and L-Serine (Ser). The Glu-AA mixtures were reacted at 60, 120, and 160 °C for 1 h. The 4-MeI levels were measured by gas chromatography-mass spectrometry after derivatization with isobutylchloroformate. No 4-MeI was formed at 60 °C for any treatment combination; however, at 120 °C and 0.05 M, Glu-Arg and Glu-Lys produced 0.13 and 0.14 mg/kg of 4-MeI. At 160 °C and 0.05 M all treatment combinations formed 4-MeI. At 160 °C and 0.15 M, the observed levels of Glu-Ala, Glu-Arg, Glu-Gly, Glu-Lys, and Glu-Ser were 0.21, 1.00, 0.15, 0.22, and 0.16 mg/kg. The AA type, reactant concentrations, and temperature significantly affected (P < 0.001) formation of 4-MeI as well as browning. Glu-Lys treatment in all combinations produced the most browning, but Glu-Arg produced the most 4-MeI. This method showed that foods processed using low temperatures may have reduced levels of 4-MeI.
authors.affiliation: Food Science Institute, Dept. of Animal Sciences and Industry, 208 Call Hall, Kansas State Univ., Manhattan, Kans., 66506, U.S.A.
authors.forename: Faris
authors.initials: F
authors.lastname: Karim
authors.affiliation: Food Science Institute, Dept. of Animal Sciences and Industry, 208 Call Hall, Kansas State Univ., Manhattan, Kans., 66506, U.S.A.
authors.forename: J Scott
authors.initials: JS
authors.lastname: Smith
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D002273:Carcinogens / Q000378:metabolism*; D005511:Food Handling / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000378:metabolism*; D015416:Maillard Reaction; D008954:Models, Biological; D012996:Solutions; D013696:Temperature; D014867:Water
chemical_list: D000596:Amino Acids; D002273:Carcinogens; D007093:Imidazoles; D012996:Solutions; D014867:Water; D005947:Glucose; C023439:4-methylimidazole
keywords: 4(5)-methylimidazole; amino acids; caramel color