Interactions between Pea Protein Isolate and Carboxymethylcellulose in Neutral and Acid Aqueous Systems

Pea protein isolate (PPI), as an emerging plant protein, has gradually aroused the attention of the public, but the PPI, especially high-concentration PPI’s low stability in the acidic aqueous system, was still a problem that limited its application. In this research, we investigated the interactions between relatively high concentrations of PPI (3.0%) and carboxymethylcellulose (CMC, 0–0.5%) in neutral and acid aqueous systems to explore the change of the phase behavior and stability of PPI as affected by CMC. It showed that the stability of PPI in the aqueous systems strongly depended on the CMC concentration, especially at the acidic aqueous systems. At neutral aqueous system, a certain amount addition of CMC into the PPI caused serious phase separation. While stable PPI solutions can be obtained at a narrow region around pH 4.5 to 5.5 by adding different amounts of CMC. The enhancement in the electrostatic repulsion and steric hindrance between the newly formed PPI-CMC biopolymers, as well as the increase in bulk viscosity with the adding of CMC at pH 4.5, contributed to the higher stability of PPI in acidic aqueous systems.