Detection and quantification of 4(5)-methylimidazole in cooked meat

4(5)-Methylimidazole (4-MeI) is a nitrogen-containing heterocyclic compound found in class III and IV ammoniated caramel colors, a group of additives widely used in the food industry. A suspected carcinogen and neurotoxin and efforts are underway to limit its presence in foods. Several methods have been developed to detect and quantitate 4-MeI in different food matrices, including roasted coffee, beer, soft drinks, and soy sauce; however, no methods are available to measure 4-MeI in cooked meat and meat products containing lipids and high levels of interfering nitrogen compounds, such as amino acids and peptides. A rapid method using 0.1 M sodium acetate buffer (pH 5) as an extraction solvent followed by derivatization with isobutylchloroformate and gas chromatograph mass-spectrometry was developed to quantify 4-MeI in cooked meat products with added caramel colors containing 4-MeI. Selected ion monitoring mode was used to monitor 4-MeI ions fragments. In the 8 commercial meat products tested, 4-MeI levels ranged from 0.041 to 1.015 mg/kg, with recovery of 94.76% to 103.94%. In addition, a matrix-matched calibration performed by analyzing a spiked cooked meat sample indicated no significant difference (P > 0.05), which means the meat matrix had no effect on the developed method. This method proved useful in analyzing 4-MeI in meat products with added caramel color containing 4-MeI.