Biodegradable starch-based packaging films incorporated with polyurethane-encapsulated essential-oil microcapsules for sustained food preservation

Novel starch-based packaging films with sustained antibacterial activity were successfully made by incorporating polyurethane-encapsulated essential-oil microcapsules (EOs@PU) as an alternative synthetic preservative for food preservation. Herein, three essential oils (EOs) were blended to make composite essential oils with a more harmonious aroma and higher antibacterial ability and encapsulated into polyurethane (PU) to form EOs@PU microcapsules based on interfacial polymerization. The morphology of the constructed EOs@PU microcapsules was regular and uniform with an average size of approximately 3 mu m, thus enabling high loading capacity (59.01 %). As such, we further integrated the obtained EOs@PU microcapsules into potato starch to prepare food packaging films for sustained food preservation. Consequently, the prepared starch-based packaging films incorporated with EOs@PU microcapsules had an excellent UV blocking rate (>90 %) and low cell toxicity. Notably, the long-term release of EOs@PU microcapsules gave the packaging films a sustained antibacterial ability, prolonging the shelf life of fresh blueberries and raspberries at 25 degrees C (> 7 days). Furthermore, the biodegradation rate of food packaging films cultured with natural soil was 95 % after 8 days, clarifying the excellent biodegradability of the packaging films for environmental protection. As demonstrated, the biode-gradable packaging films provided a natural and safe strategy for food preservation.