Design and characterization of tannic acid/E-polylysine biocomposite packaging films with excellent antibacterial and antioxidant properties for beef preservation

The shelf life of beef is shortened by microbial infection, which limits its supply in the market. Active packaging film is expected to overcome this difficulty. In this study, an antibacterial/antioxidant SS-E-PL-TA biocomposite film made by soy protein isolate/sodium alginate/E-polylysine/tannic acid was designed and prepared. Due to the formation of hydrogen bonds and enhanced hydrophobic interactions, the biocomposite film showed enhanced mechanical property. Tensile strength increased from 22.8 +/- 2.59 MPa to 64.34 +/- 6.22 MPa, and elongation at break increased from 7.70 +/- 1.07 % to 13.98 +/- 0.22 %. The composite film displayed excellent antibacterial activity owing to the damage to cell membranes and biofilms of bacteria. Furthermore, the anti-oxidant activity also significantly increased (DPPH center dot scavenging activity was 78.0 %). The shelf life of beef covered with the SS-E-PL-TA film was extended by 3 days compared to the control group by decreasing lipid oxidation and inhibiting bacterial growth, showing a good application potential in food packaging.