Investigation and kinetic evaluation of the reactions of hydroxymethylfurfural with amino and thiol groups of amino acids

In this study, reactions of hydroxymethylfurfural (HMF) with selected amino acids (arginine, cysteine and lysine) were investigated in HMF-amino acid (high moisture) and Coffee-amino acid (low moisture) model systems at 5, 25 and 50 °C. The results revealed that HMF reacted efficiently and effectively with amino acids in both high and low moisture model systems. High-resolution mass spectrometry (HRMS) analyses of the reaction mixtures confirmed the formations of Michael adduct and Schiff base of HMF with amino acids. Calculated pseudo-first order reaction rate constants were in the following order; k_Cysteine > k_Arginine > k_Lysine for high moisture model systems. Comparing to these rate constants, the k_Cysteine decreased whereas, k_Arginine and k_Lysine increased under the low moisture conditions of Coffee-amino acid model systems. The temperature dependence of the rate constants was found to obey the Arrhenius law in a temperature range of 5–50 °C under both low and high moisture conditions.