Formation and characterization of protein-based films from yellow pea (Pisum sativum) protein isolate and concentrate for edible applications

This study investigated the properties of films or bioplastics fabricated using a wet processing method from yellow pea protein isolate (YPI) and protein concentrate (YPC) for potential application in food packaging. The wet processing method included mixing the protein with water and glycerol followed by casting and drying the films in a humidity- and temperature-controlled chamber. Whey protein isolate (WPI) and a film from a blend of equal amounts of YPI and WPI, labelled as YPI thorn WPI, were also studied. Fourier transform-infra red analysis revealed that films from YPI, YPC, WPI and YPI thorn WPI were formed by protein polymerisation with the plasticiser, glycerol, via hydrophobic and hydrophilic interactions. The protein films had contact angles of <90 degrees demonstrating that they had a hydrophilic surface, with YPC < YPI < YPI thorn WPI < WPI. The pattern of ultraviolent light transmission of the films was WPI > YPC > YPI thorn WPI > YPI, whereas the mechanical and thermal resilience of films formulated from YPI, YPC and the protein blend were comparable to the properties of WPI-based films. The findings demonstrate that yellow pea proteins can be used as biomaterials to develop protein and protein-blend films or bioplastics for food packaging and edible applications.