IMPROVEMENT OF PROTEIN GEL BY PHYSICAL AND ENZYMATIC TREATMENT

To improve the functional properties of food protein, physical and enzymatic treatments are effective and attractive. As an example of physical treatment, heat treatment of egg protein under various conditions is shown. Egg albumin and egg white usually give turbid (white) gel on heating. However, we have learned that a transparent gel can be prepared by regulating conditions of the medium. The molecular mechanism for formation of such gels and the physical properties of transparent and turbid gels are shown. Proteolytic enzymes are often used to improve the properties of food protein, but sometimes bitter peptides are formed. Therefore, a limited proteolysis rather than nonspecific hydrolysis is preferable and effective in order to change the functional properties. We have shown that pepsin promotes limited proteolysis under pH control. Not only proteolytic enzyme, but other enzymes are also useful for improving food protein. Possibilities of the use of enzymes for food processing are shown here.