Effects of pH changes on functional properties of native and acetylated wheat gluten

Wheat gluten is an abundant plant protein with many applications in food and non-food products. However, hydrophobicity of the gluten has limited its applications. Acetylation as a common method for protein modification, can improve gluten hydrophilicity. The functional properties of the native and acetylated gluten are affected by the pH of the environment. The main aim of this study was to determine the effects different pH values of 3, 6 and 9 on the functional characteristics of the native and acetylated gluten. Acetylation of the gluten using acetic anhydride under alkaline condition resulted in 44.58% acetylation. The isoelectric point of the native gluten was 6.2 that reduced to 4.4 after acetylation. Upon acetylation water solubility, water absorption, water holding capacity, foaming and emulsifying properties of the gluten improved, significantly (p 0.05). Increasing the pH from 3 to 6 weakened, while further increase of the pH from 6 to 9 enhanced the functional properties of the native gluten. Nevertheless, increasing the pH from 3 to 9 enhanced the functional properties of the acetylated gluten. In total, native gluten can be used for its functional properties in products of acetic or alkaline pH, while acetylated gluten is more suitable in alkaline products.