Characterization of structural, functional and antioxidant properties and amino acid composition of pepsin-derived glutelin-1 hydrolysate from walnut processing by-products

Glutelin-1 of defatted walnut meal protein (DWPG-1) was modified by pepsin enzymatic hydrolysis to improve its functional properties and antioxidant activities. The amino acid composition, structural characteristics, physicochemical and functional properties as well as antioxidant activities of the hydrolysate were compared with those of unmodified DWPG-1. The analysis of X-ray diffraction patterns, surface microstructure and particle size distribution indicated that enzymatic hydrolysis changed the structures of DWPG-1. Compared with the natural unhydrolyzed protein, the hydrolysate showed better physicochemical properties, such as surface hydrophobicity, solubility, emulsifying properties, foaming properties and water absorption capacity. In addition, the hydrolysate also exhibited significantly stronger antioxidant activities than DWPG-1. In conclusion, the results of this study prove that pepsin-mediated hydrolysis of walnut glutelin-1 can effectively modify the structure, function and antioxidant activity of DWPG-1, and could be used as an effective technology to produce bioactive multifunctional hydrolysates.