Sonochemical effects on formation and emulsifying properties of zein-gum Arabic complexes

Abstract

Zein is a widely used plant protein, but its application is limited by its poor water solubility under neutral conditions. In this work, we present an approach to develop a water-soluble zein-gum arabic (GA) complex and to explore its application in stabilizing lemon oil-in-water emulsions. As a simple, inexpensive and rapid method, sonication was used to accelerate the glycation reaction between zein and GA. The grafting degree of zein and GA was highest when the sonication power was 400 W and the treatment time was 25 min. SDS-PAGE and 1H NMR confirmed the formation of covalent bonds between zein and GA. The water-dispersibility, antioxidant activity, and thermal stability of zein-GA conjugates were better than those of native zein. The conjugates were used to form stable high internal phase emulsions (HIPEs) containing 80% v/v oil, which had relatively small mean droplet diameter (<10 μm). The HIPEs were semi-solids that exhibited strong shear-thinning behavior. After encapsulation in the HIPEs, the chemical degradation of lemon oil when exposed to UV-light and heat was significantly reduced. This study shows that the functional performance of zein can be extended by covalently linking it to GA using a combination of sonication and heat.