Plasma-treated polylactic acid films combined with ε-polylysine-chitosan coatings for fresh pork packaging

Due to threats of environmental pollution and food safety, the polylactic acid (PLA) was treated by plasma prior to coating chitosan (CS)/ε-polylysine (ε-PL) to expand the application in active packaging. Air plasma significantly enhanced the compatibility of PLA with coating to obtain a closely integrated bilayer ε-PL-CS/PLA. The coating endowed antibacterial activity of PLA from 0 % to 57.06 % for <i>E. coli</i> and 33.17 % for <i>S. aureus,</i> and decrease its oxygen barrier properties dramatically from 127.33 to 1.73 cm³/m²·24h·0.1 MPa. Increasing the ε-PL content enhanced the elongation at break, hydrophilicity and bioactivity of ε-PL-CS/PLA, while reduced the tensile strength and moisture barrier properties. In food applications, the ε-PL-CS/PLA films effectively delayed the change in redness, pH, TVC and TVB-N during storage, prolonging the shelf life of pork from 2 d (PLA) to 8 d (10 %-ε-PL-CS/PLA). This study confirms the potential of modified-PLA films with excellent antibacterial properties for active packaging.