Impact of Calcium Chloride Addition on the Microstructural and Physicochemical Properties of Pea Protein Isolate-Based Films Plasticized with Glycerol and Sorbitol.

Ca²⁺ can boost protein-protein interactions and, if present at an appropriate level, can potentially improve some physicochemical properties of protein-based gels and films. This study aimed to determine the effects of CaCl₂ (0%–0.05% w/w) on the microstructural, optical, water affinity, and mechanical characteristics of glycerol (Gly)- and sorbitol (Sor)-plasticized pea protein isolate (PPI)-based films. CaCl₂ caused darkening and a color shift of the films from yellow to yellow-green. Additionally, decreased light transmission, particularly in the UV range, acidification, and reduced moisture content were observed. CaCl₂ decreased the water vapor permeability of the Gly plasticized film by an average of 20% with no effect on the Sor-plasticized film. All films were completely soluble in water. CaCl₂ negatively impacted the mechanical integrity of the films, reducing the tensile strength of the Gly- and Sor-plasticized films by ~16% and 14%–37%, respectively. Further increases in CaCl₂ content (0.1% and 0.2% w/w) led to concentration-dependent microvoids resulting from protein over-crosslinking and/or coagulation. In summary, the incorporation of CaCl₂ into PPI-based films did not provide significant benefits and actually worsened key properties, such as transparency and mechanical strength. The type of plasticizer influenced how CaCl₂ affected some properties of the PPI-based film. [ABSTRACT FROM AUTHOR]