Properties and biological activity of chitosan-coix seed starch films incorporated with nano zinc oxide and Artemisia annua essential oil for pork preservation

Edible films based on chitosan, coix seed starch (CSS), nano zinc oxide (ZnO) and Artemisia annua essential oil (AO) were obtained through solvent casting method. Physico-chemical, biological properties and structures of the edible film were analyzed and the preservation effect of it on the quality of cold-stored pork was also investigated. Fourier-transform infrared spectroscopy (FTIR) indicated that some possible intermolecular interactions could exist between film matrix and ZnO or AO. Scanning electron microscope (SEM) and thermogravimetry (TG) showed that ZnO and AO had good compatibility with the film biopolymers, no any phase separation. Results suggested that appropriate content of ZnO could enhance the film's compactness. Tensile strength (TS), barrier properties and antibacterial activities of the film was significantly enhanced with 5% ZnO was added. Incorporation of AO into the edible film decreased the TS, but increased the flexibility, barrier properties, antibacterial and antioxidant activities. When content of ZnO and AO were 5% and 8%, the physicochemical, biological properties of the edible film could reach optimum. For pork preservation, pH, thiobarbituric acid reactive substances (TBARS), total viable count (TVC), and total volatile basic nitrogen (TVB-N) values of the pork which treated with 5% ZnO-8% AO film were significantly lowest (p <= 0.05) than other groups. Therefore, this edible film system has potential as food packaging materials.