Development of Plastic/Gelatin Bilayer Active Packaging Film with Antibacterial and Water-Absorbing Functions for Lamb Preservation

In order to extend the shelf life of refrigerating raw lamb by inhibiting thegrowth of microorganisms, preventing the oxidation of fat and protein, andabsorbing the juice outflow of lamb during storage, an active packaging systembased on plastic/gelatin bilayer film with essential oil was developed in thisstudy. Three kinds of petroleum-derived plastic films, oriented polypropylene(OPP), polyethylene terephthalate, and polyethylene, were coated with gelatin tomake bilayer films for lamb preservation. The results showed significantimprovement in the mechanical properties, oxygen, moisture, and light barriersof the bilayer films compared to the gelatin film. The OPP/gelatin bilayer filmwas selected for further experiments because of its highest acceptance bypanelists. If the amount of juice outflow was less than 350% of the mass of thegelatin layer, it was difficult for the gelatin film to separate from lamb. Withthe increase in essential oil concentration, the water absorption capacitydecreased. The OPP/gelatin bilayer films with 20% mustard or 10% oreganoessential oils inhibited the growth of bacteria in lamb and displayed bettermechanical properties. Essential oil decreased the brightness and lighttransmittance of the bilayer films and made the film yellow. In conclusion, ourresults suggested that the active packaging system based on OPP/gelatin bilayerfilm was more suitable for raw lamb preservation than single-layer gelatin filmor petroleum-derived plastic film, but need further study, including minimizingthe amount of essential oil, enhancing the mechanical strength of the gelatinfilm after water absorption.