Soy protein-polysaccharide complex coacervate under physical treatment: Effects of pH, ionic strength and polysaccharide type

Abstract

Abstract The objective of this paper is to explore the effects of pH, ionic strength and polysaccharide type on the aqueous phase behaviors and rheological properties of soy protein isolate-chitosan (SPI-CS) and soy protein isolate-carboxymethyl cellulose (SPI-CMC) coacervates treated by vortex fluidic device (VFD) and shear homogenization. Characterization in terms of phase behavior and microstructures depicted that the VFD and shear homogenization treatments affected only the SPI-CS complex. According to the ζ-potential values at tested pHs (3.0–8.0), both physical processing had insignificant effect on charge stabilization of protein-polysaccharide complex. Both the SPI-CS coacervates (at pH\xa07.0) and SPI-CMC coacervates (at pH\xa03.0) showed gel-type rheological behaviors (G′\xa0>\xa01000\xa0Pa), suggesting that the SPI and polysaccharides did not form complex coacervate (liquid in nature) but interpolymeric complex (solid in nature). In the absence of salt ions, independent on the type of coacervate, VFD slightly decreased the modulus (G′