The coexistence of carboxymethylcellulose and transglutaminase modified the physicochemical properties and structure of whey protein concentrate films

Whey protein concentrate (WPC) and carboxymethyl cellulose (CMC) were abundant in nature and biodegradable raw materials, which have a wide range of prospects for developing bioactive food packaging. In order to exploit the complementary functional properties, in this study CMC was incorporated into WPC films and modified by transglutaminase (TG). The physicochemical properties and structure characteristics of the composite films were investigated. Results showed that CMC as a filler of the protein network significantly improved the properties of WPC films, while TG contributed to the mechanical properties. The composite (1:1) film containing 10 U/g(protein) of TG possessed a maximum tensile strength of 13.34 MPa compared to the WPC film. The addition of CMC and TG effectively improved the structure of the film, reducing the pore diameterr, so the composite film with TG at 10 U/g(protein) showing a dense structure, with improved light transmission (37.42%) and water vapour transmission (5.06). FT-IR and SEM results reflected that TG induced covalent cross-linking between proteins and WPC and CMC had good compatibility. These suggest that the coexistence of CMC and TG has positive effect on the formation of composite films prepared by TG cross-linking WPC and CMC blends, which provided a promising alternative method for the development of good edible films or coatings for food packaging in the future.