Study on packaging performance and antimicrobial properties of antibacterial composite protein films

The composite protein film-forming materials contained 5% whey protein isolate (WPI) , 2% sodium caseinate (NaCas) and 50% glycerol, which was the optimal formula obtained by uniform design method of previous work. The packaging performance and antimicrobial properties of WPI-NaCas composite protein films were discussed by addition of Nisin at different concentrations (0, 0.025, 0.05, 0.075, 0.1g/200mL) in film-forming solution. Results showed that Nisin and composite protein films showed good compatibility. Addition of Nisin could improve tensile strength and elongation at break of the composite protein films and decrease WVP values of the films, with no effect on the sealing temperature of antibacterial protein films. The increase of Nisin caused the improvement of heat resistance of the films. And incorporation of Nisin had antimicrobial activity against both E.coli and S.aureus.