Physicochemical and microstructural properties of whey protein isolate-based films with addition of pectin

The interest in edible packaging films as a possible substitute for petrochemical-based films has been growing over the last years. Blends of proteins and polysaccharides can be an alternative to enhance edible film properties. This work aims to develop whey protein isolate (WPI) films with pectin (PEC) addition by complex coacervation method and to evaluate the effect of polysaccharide addition on film properties. Blended films were elaborated using WPI and four concentrations of PEC. Interaction between WPI and PEC was evaluated through ζ-potential. Solubility, moisture sorption behavior, optical, barrier and mechanical properties and microstructure of films were evaluated. The results showed that PEC electrostatically interacted with WPI at pH 3.0, reducing the ζ-potential to values close to zero. The interaction between compounds increased the opacity, solubility and permeability to water vapor, but decreased the flexibility and tensile strength of WPI films. With the increase of pectin concentration, the electrostatic interaction was reduced and the non-complex pectin that, was present in excess, improved the mechanical properties of films.