Effects of Galactose Concentration on Characteristics of Angiotensin-I-Converting Enzyme Inhibitory Peptides Derived from Bovine Casein in Maillard Reaction

Bovine casein peptide had a strong angiotensin-I-converting enzyme inhibitory activity. The objective of this study was to evaluate the effects of the galactose concentration on angiotensin-I-converting enzyme inhibitory activity, antioxidant activity, and physicochemical properties of Maillard reaction products derived from bovine casein peptide and galactose in aqueous model system. The browning intensities of galactose-bovine casein peptide Maillard reaction products increased remarkably with the galactose concentration increased during heat treatment, while its pH and amino groups decreased significantly. The fluorescence compounds of galactose-bovine casein peptide Maillard reaction products reached the maximum when the galactose concentration was 45 g/L. Compounds with molecular weight between 2941 and 8864 Da were dominant while compounds smaller than 250 Da were also produced during the reactions, as characterized by size exclusion chromatography. Galactose-bovine casein peptide Maillard reaction products lost 14.6% of the original angiotensin-I-converting enzyme inhibitory activity of bovine casein peptide after the addition of galactose concentration ranged from 0 to 12%, but its strong antioxidant activities were obtained. A high galactose concentration could decrease angiotensin-I-converting enzyme inhibitory activity of bovine casein peptide and enhance its antioxidant activities.