Evaluation of Interactions Between Carboxymethylcellulose and Soy Protein Isolate and their Effects on the Preparation and Characterization of Composite Edible Films

Abstract

Interactions between carboxymethylcellulose (CMC) and soy protein isolate (SPI) were assessed to determine their effects on the physicochemical and morphological properties of SPI-based films. The protein-polysaccharide interactions were investigated by measuring zeta potentials, showing a dependence on the pH, ionic strength and polysaccharide concentration. SPI-based films were prepared with different CMC concentrations (0–0.5%) at pH 11 and the pH of biopolymer coacervation (pHc). The addition of CMC improved mechanical strengths of all films, but films prepared at pHc showed a reduction in percentage of elongation at break, becoming more brittle than at pH 11. The water vapor permeability did not show a strict dependence on the CMC concentration or pH, while the oxygen permeability of films prepared at pH 11 decreased with the addition of CMC until reaching a minimal value at 0.375% CMC. These results reveal the significant effects of SPI-CMC interactions on the formation and properties of films, indicating the potential of this approach to better tailor edible films and coatings for specific applications.