Development and characterization of antimicrobial and antioxidant whey protein-based films functionalized with Pecan (Carya illinoinensis) nut shell extract

Aim of this study was the development of an active packaging based on whey proteins (WP) functionalized with Pecan nut shell extract (PNSE). To this purpose, aqueous solutions of WP, PNSE and glycerol were mixed and characterized, whereas corresponding films were prepared by casting. Zeta-potential measurement revealed that the film forming solutions were stable, and the particle size was reduced further to the incorporation of PNSE, as a result of tannins-WP interactions. Films were handleable and homogeneous, and PNSE was able to improve their mechanical and barrier properties. PNSE-containing films inhibited the growth of the foodborne bacteria Enterococcus faecalis and Salmonella enterica subsp. enterica ser. Typhimurium. Ferric reducing/antioxidant power assay clearly highlighted the ability of PNSE to impart antioxidant properties to the films. Finally, simulated digestion experiments showed a significant lowering of the proteolysis rate in the presence of PNSE, although 40 % of the protein was still digested after 60 min incubation. Overall, these results put the basis for a possible use of PNSE functionalized WP-based films as new environmentally friendly candidates for increasing the shelf-life of foods.