Temperature effect on the non-volatile compounds of Maillard reaction products derived from xylose-soybean peptide system: Further insights into thermal degradation and cross-linking

Solutions of soybean peptide with or without xylose were heated over a range of temperatures (80-130 degrees C) for 2 h to investigate the characteristics of Maillard reaction and the effect of temperature on amino acids and peptides. It was found that both peptide degradation and peptide cross-linking occurred in the Maillard reaction. The critical temperature for peptide degradation was 100 degrees C, and above it, peptides degraded quickly in thermal degradation system. However, in Maillard reaction system, peptides cross-linked rapidly when the temperature reached 110 degrees C. Bitter amino acids and peptides below 1000 Da decreased 18.44% and 28.49%, respectively, after Maillard reaction at 120 degrees C. On the other hand, peptides between 1000 and 5000 Da were increased significantly, nearly doubled compared to its initial hydrolysates after Maillard reaction at 120 degrees C. Moreover, the increase of macromolecule products was also accompanied with severe browning and pH decrement. (C) 2009 Elsevier Ltd. All rights reserved.