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Formation of 4(5)-Methylimidazole in Aqueous d-Glucose-Amino Acids Model System

Faris Karim1, J Scott Smith1

  • 1Food Science Institute, Dept. of Animal Sciences and Industry, 208 Call Hall, Kansas State Univ., Manhattan, Kans., 66506, U.S.A.

Journal of Food Science
|November 19, 2015
PubMed

Insights

The formation of 4(5)-methylimidazole (4-MeI), a possible carcinogen, increases with higher temperatures and concentrations in D-glucose and amino acid mixtures. Lower processing temperatures in foods can reduce 4-MeI levels.

Area of Science:

  • Food Chemistry
  • Chemical Carcinogenesis

Background:

  • 4(5)-methylimidazole (4-MeI) is classified as a Group 2B possible human carcinogen by the International Agency for Research on Cancer (IARC).
  • Understanding 4-MeI formation in food systems, particularly during heating processes involving sugars and amino acids, is crucial for food safety and quality.
  • Browning reactions, often associated with desirable flavors and colors, can be linked to the formation of potentially harmful compounds like 4-MeI.

Purpose of the Study:

  • To investigate the formation of 4-MeI in a model system composed of D-glucose (Glu) and various amino acids (AAs) under different temperature and concentration conditions.
  • To determine the influence of amino acid type, reactant concentration, and temperature on 4-MeI production and browning.
  • To assess the potential for reducing 4-MeI levels in processed foods by controlling processing parameters.

Main Methods:

  • An aqueous model system was created by mixing D-glucose with equimolar concentrations of L-Alanine, L-Arginine, Glycine, L-Lysine, and L-Serine at 0.05, 0.1, and 0.15 M.
  • Mixtures were heated at 60, 120, and 160 °C for 1 hour.
  • 4-MeI levels were quantified using gas chromatography-mass spectrometry (GC-MS) after derivatization with isobutylchloroformate.

Main Results:

  • No 4-MeI was detected at 60 °C across all tested conditions.
  • Significant 4-MeI formation was observed at 120 °C and 160 °C, with levels increasing with both temperature and concentration.
  • At 160 °C and 0.15 M, L-Arginine yielded the highest 4-MeI (1.00 mg/kg), while L-Lysine induced the most browning across all conditions.
  • Amino acid type, concentration, and temperature were significant factors (P < 0.001) influencing both 4-MeI formation and browning.

Conclusions:

  • The formation of 4-MeI is highly dependent on reaction temperature, concentration, and the specific amino acid present.
  • Processing foods at lower temperatures can significantly mitigate the formation of 4-MeI.
  • This study provides valuable insights for developing strategies to minimize carcinogenic byproducts in thermally processed foods.
Keywords:
4(5)-methylimidazoleamino acidscaramel color

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