Production of wheat gluten hydrolysates with improved functional properties: optimization of operating parameters by statistical design

Abstract

Introduction: Native wheat gluten is a deluxe bread improver and may be utilized as a functional protein additive in multifarious nonbakery foodstuffs due to its desirable structure-enhancing properties. Also its utilization would be economically interesting, but lack of some desirable functional properties limited their expanding utilization in foodstuff formulations [1]. This study was designed to examine the relationship between process parameters and functional properties of the obtained hydrolysates using Box-Benken experimental design and response surface methodology (RSM). The hydrolysate showing the highest improvement of solubility and foaming ability was further separated by sequential ultrafiltration to obtain molecular weight distribution profile. Materials and methods: The progress of wheat gluten hydrolysis was followed by monitoring the degree of hydrolysis (DH) using the pH-stat method and functional properties were measured by our methods already adopted [2]. The effects of process parameters (pH, T, [S], [E]/[S] ration) and their interactions were investigated by the means of the four-factor Box-Behnken experimental design with 29 experimental points (5 central points). Results: The obtained results showed that the second-order models developed for DH, solubility and foaming properties of gluten hydrolysates were significant (p<0.05) with a high value of coefficients of determination (0.944-0.981). The statistical analysis showed that each variable had a significant effect on degree of hydrolysis and the functional properties of tested system. Almost the linear increase in DH was observed with the rise in temperature at the highest substrate concentration, while on the other hand increasing the concentration of the substrate leads to a decrease in DH. In terms of foaming properties results showed that foam capacity range are in the range of 24.2- 80.3%, depending on the independent variables that were tested. Conclusions: Results are relevant to the protein ingredient industry because of the economic importance of novel gluten–based functional products and can provide useful information for the design an efficient enzymatic process for their production in high yield and with improved functionality.