Improvement of Solubility and Emulsifying Activity of Plasma Protein by Enzymatic Hydrolysis

Abstract

Plasma protein was hydrolyzed with trypsin or pepsin in order to improve solubility and emulsifying activity. Plasma protein was only slightly hydrolyzed with trypsin. Emulsifying activity index (EAI) of plasma protein changed little by the tryptic hydrolysis. After the peptic hydrolysis, EAI of plasma protein decreased to about 50% of the original level. During heat treatment of these hydrolyzates, EAI of the tryptic hydrolyzates decreased, while EAI of the peptic hydrolyzates changed little. The peptic hydrolyzates were fractionatedusing hydrophobic chromatography. The hydrophilic fraction showed lower EAI than that of the peptic hydrolyzates and the hydrophobic fraction showed higher. It was shown that hydrophobic chromatography is effective for the preparation of a material having high emulsifying activity. After the enzymatic hydrolysis of plasma protein, hydrolyzates were ultrafiltrated and the solubility and EAI were measured. These properties were improved under several conditions of pH and ionic strength by the combination of enzymatic hydrolysis and ultrafiltration.