Hydrolyzing behaviors of endogenous proteases on proteins in sesame milk and application for producing low-phytate sesame protein hydrolysate

Abstract

Endogenous proteases with high activity have been identified in sesame seeds. However, the hydrolyzing behaviors of endogenous proteases on proteins in sesame milk are not well understood. In this study, the endogenous proteases optimally hydrolyzed proteins at pH 4.5 and 50 °C for 6 h. Tricine–sodium dodecyl sulphate–polyacrylamide gel electrophoresis and liquid chromatography tandem mass spectrometry analyses revealed that endogenous proteases randomly cleaved the cleavable peptide bonds on 11S globulins, and amino acid analysis indicated that serine carboxypeptidases preferentially cleaved tryptophan, phenylalanine, methionine, tyrosine, and leucine. The hydrolyzed sesame milk was separated into cream, transparent skim, and precipitate fractions by centrifugation (3000g, 5 min). The major protein components in skim were 42% peptides (<1500 Da) and 35% free amino acids. The phytate in skim was greatly reduced by adjusting to neutral and alkaline pH. This study is meaningful at supplying a strategy for producing low-phyate sesame protein hydrolysate.