Mechanisms behind the changes in zein colloidal composite nanoparticles under different mass ratios and pH conditions

Abstract

The hydrophobicity of zein (Z) makes it a candidate for encapsulating hydrophobic compounds and stabilizing Pickering emulsions. However, the high aggregation tendency of Z colloidal particles has limited its applications. Using an available and low-cost hydrophilic biopolymer to coat Z colloidal particles is an efficient way to increase their applications. In this work, the aggregation of Z particles was modulated by incorporating Farsi gum (FG), an emerging hydrocolloid with attractive characteristics, into the colloidal particles. Z/water-soluble portion of FG (WFG) particles were fabricated at pH range of 3–7 and 10:1–1:2 mass ratios using an anti-solvent procedure and then characterized. Zeta potential values indicated that in the presence of WFG, the colloidal stability of the particles increased. At higher pH values (pH 7), the Z:WFG (1:1) colloidal particles were smaller than the Z particles. Although WFG incorporation decreased the interfacial adsorption rate of particles due to the higher molecular weight and viscosity of the system, both Z and Z:WFG particles could efficiently reduce interfacial tension. The interfacial layer films developed by Z (pH 4) and Z: WFG (pH 4) particles revealed non-Newtonian and dominant viscouse (G″>G′) characters. This work can help to design Pickering emulsions using alcohol-soluble-based particles.