Understanding glycation kinetics of individual peptides in protein hydrolysates

Protein hydrolysates contain peptides with different lengths, type (α/ε-) and number of amino groups; these properties might influence the peptide glycation kinetics during the Maillard reaction. To identify the effects of peptide properties and hydrolysate composition on glycation kinetics, the glycation kinetics of individual peptides in hydrolysates was followed using quantitative peptide analysis. α-Lactalbumin was hydrolysed and glycated with d-glucose (0–8 h, 50 °C, dry heating with 65% humidity). The hydrolysates (degree of hydrolysis 2, 4, 6, and 8%) contained 25 unique peptides, ranging from 2 to 123 AAs with 0–12 lysine(s). The glycation rate constant (kg) and the maximum average degree of glycation (DG_Pav,max) of peptides were independent of the hydrolysate composition. The maximum DG of α-NH2 and ε-NH2 groups was 12.8% and 60.0%, respectively. With this information, the DG_Pav,max of individual peptides [9–59% for peptides with 0–2 lysine(s)] could be predicted.