Development of slow release antibacterial polylactic acid bilayer active film with different distributions of clove essential oil and its application for snakehead (Channa argus) preservation

The antibacterial polylactic acid (PLA) bilayer active films with slow release property were developed by utilizing the different distributions of clove essential oil (CEO) in two layers. The effect of CEO different distribution on the films' properties and their application in snakehead packaging were studied. The FTIR spectra and SEM indicated that CEO was successfully incorporated into the PLA films. The incorporation of CEO enhanced tensile strength, gas barrier properties of the films and provided the films with UV resistance, good antibacterial and antioxidant activities. The different distributions of CEO didn't significantly affect the color, transparency, and gas barrier properties of the films. But they influenced the mechanical properties, recovery rate of CEO and the release behavior, showing that the film with higher unilateral CEO exhibited higher tensile strength, bigger elongation at break and higher loss of CEO. The film with higher CEO in outer layer released CEO more slowly into food simulant (10% ethanol). This was also reflected by their different antibacterial and antioxidant activities of the films due to the different distributions of CEO. The films containing CEO could efficiently inhibit the microorganism's growth and the protein decomposition of snakehead during storage. The snakehead packed by the film containing 4% CEO in outer layer and 2% CEO in inner layer exhibited the best quality stability. The concept of this work showed great potential in developing slow release active films for food packaging.