Application of Two- or Three-Step Enzymatic Hydrolysis for Efficient Production of Wheat Gluten Hydrolysates

Abstract

Wheat gluten, a coproduct in wheat starch industry, possesses poor water solubility, which limits its broad application in the food industry. Enzymatic hydrolysis has been used to enhance functional properties of proteins and to produce bioactive peptides. In the food industry, it is prerequisite to produce protein hydrolysates in an economical and efficient approach. The objective of this study was to develop an efficient production method of wheat gluten hydrolysates (WGH) with desirable properties to be applied in beverages by sequential enzymatic hydrolysis. In the present study, limited conditions, such as high solid loading (25%, w/w), low protease concentration (1:300, w:w) and limited hydrolysis time (6 h), were employed to produce WGH. Endo-proteases (Protamex, P

Alcalase, A

and Neutrase, N) and endo- and exo-protease mixture (Flavourzyme, F) were used. In order to explore suitable sequences for enzymatic hydrolysis of wheat gluten, various combinations of endo-proteases were tested. Yields of water-soluble WGH were 59.3-65.7%. Sequential hydrolyses by combination of A with other endo-proteases produced WGH with significantly (p<0.05) higher proportions (more than 50%) of fractions below 1 kDa than the others. The WGH produced by N-P sequence showed the lowest bitterness among the WGH. A5F1, N5F1, A4P1F1, N4P1F1, A3N2F1 and N3A1F1 (numbers representing hydrolysis time) possessed lower turbidity, better thermal stability and higher L* values than the others. The WGH produced by P-A and A-P sequences exhibited higher DPPH radical scavenging activities than the others. The A4P1F1 showed better properties to be applied in beverages than the others. In vitro digests of the A4P1F1 exhibited antioxidant activities, especially reducing power and copper chelating activity.