Development of active packaging films based on collagen/gallic acid-grafted chitosan incorporating with ε-polylysine for pork preservation

Active packaging films (CCG/PL) based on collagen, functionalized chitosan with gallic acid (GA), and ε-polylysine (ε-PL) (different amount of 2.5, 5, and 10 wt%, respectively) were developed to prolong the shelf life of pork stored at 4 °C. Fourier transform infrared analysis indicated that hydrogen bonds had formed between collagen molecules and GA moieties, and there were no strong interactions between polymers and ε-PL. SEM images showed that the cross-sections of CCG/PL films were compact but aggregation of ε-PL occurred when ε-PL content reached 10 wt%. CCG/PL films possessed strong light barrier properties with the UV light transmittance lower than 4% in the range of 200–350 nm. Compared with CC film, the DPPH free radical scavenging rate was significantly increased by 84.35% due to the synergistic effect of GA and ε-PL on antioxidant activity. CCG/PL film containing 5 wt% ε-PL had excellent antimicrobial activity against S. aureus as well as good tensile strength (65.34 MPa). The wrapping of CCG/PL film with 5 wt% ε-PL effectively retarded the lipid oxidation of pork and inhibited the growth of bacterium during the storage time, and the shelf life of pork was prolonged by approximately 5 days than that of pork in polyethylene film.