PREPARATION AND CHARACTERIZATION OF MODIFIED WHEAT GLUTEN BY ENZYMATIC HYDROLYSIS-ULTRAFILTRATION

Abstract

The present work was aimed to investigate the characteristics of the modified wheat gluten by enzymatic hydrolysis followed ultrafiltration membrane fractionation. An 8% aqueous dispersion of wheat gluten was hydrolyzed by papain, and then subjected to ultrafiltration membrane for fractionation. The molecular mass of the peptides released during enzymatic hydrolysis of gluten was in the range of 5,000–15,000 D according to gel permeation chromatography profiles. The resultant hydrolysate (retentate fraction) after membrane fractionation produced the desired products with a protein yield of about 89%. The modified glutens had higher surface hydrophobicity compared with the original gluten. Moreover, the modified gluten protein had superior solubility to the original gluten in pH 3–10. The enhanced foaming capacity in the pH ranges studied had been found in the modified gluten. The improved functional properties of the modified gluten were related to the well-balanced distribution of hydrophilic and hydrophobic domains. The modified gluten was rich in glutamic acid and proline. PRACTICAL APPLICATIONS Gluten is an economically important byproduct during processing of wheat starch. The expanded utilization of gluten in food and nonfood applications had been limited for lack of desirable functional properties. To extend the range of available functional properties it needs to be investigated further. The limited enzymatic hydrolysis and membrane ultrafiltration had been extensively studied and had been shown to be very effective for improving the functional properties of the proteins. In this present study, wheat gluten was modified by enzymatic hydrolysis – membrane ultrafiltration fractionation. This method was proved to be an efficient way to modify wheat gluten protein. The functional properties of the modified glutens were significantly improved compared to the original gluten. It is expected that the modified gluten with enhanced functional properties could be used in a wide range of foods as new components to enhance their nutritional value and functional properties in food processing.