Characterization of fish gelatin–gum arabic complex coacervates as influenced by phase separation temperature

Abstract

The rheological and structural characteristics of fish gelatin (FG)–gum arabic (GA) complex coacervate phase, separated from an aqueous mixture of 1% FG and 1% GA at pH 3.5, were investigated as influenced by phase separation temperature. Decreasing the phase separation temperature from 40 to 10°C lead to: (1) the formation of a coacervate phase with a larger volume fraction and higher biopolymer concentrations, which is more viscous, more structural resistant at low shear rates, more shear-thinning at high shear rates, and more condensed in microstructure, (2) a solid-like elastic behavior of the phase separated at 10°C at a high oscillatory frequency, (3) the increase in gelling and melting temperatures of the coacervate phase (3.7−3.9°C and 6.2−6.9°C, respectively), (4) the formation of a more rigid and thermo-stable coacervate gel. The coacervate phase is regarded as a homogeneously networked biopolymer matrix dispersed with water vacuoles and its gel as a weak physical gel reinforced by FG–GA attractive electrostatic interactions.