Study on preparation, characterization of Syringa reticulata var. mandshurica essential oil/polyvinyl alcohol (PVA) antibacterial composite film and its application in strawberry preservation

The essential oil of Syringa reticulata var. mandshurica (SR-EO) is extracted from the flowers of this plant. In this study, we prepared polyvinyl alcohol (PVA) antibacterial composite films with SR-EO concentrations of 2, 4, 6, 8, and 10 (g/L). We analyzed and characterized various indicators of the composite films and investigated their application in strawberry preservation.The results indicate that with an increase in SR-EO content, there is a gradual decrease in both the tensile strength and maximum tensile force of the composite film, whereas the elongation at break progressively increases. When the SR-EO content is 8 g/L, the O₂ transmission rate reaches its peak.The water vapor transmission rate and CO 2 transmission rate of the composite film with SR-EO are significantly higher than the PVA film. The mass change and thermal effect information of SR-EO/PVA films were obtained using the TG-DSC combined testing method. The X-ray diffraction results indicated that the addition of SR-EO did not alter the crystal type of the composite film.The research results indicate that the antibacterial activity of SR-EO/PVA film solution against Escherichia coli is not significant. However, the film solution exhibits significant antibacterial activity against Staphylococcus aureus and Candida albicans, and its antibacterial activity increases with the increase of SR-EO content. When the SR-EO content is 10g/L, the film solution has excellent antibacterial effects on the above two bacteria.In the strawberry preservation test, when the SR-EO content was 8 g/L, the composite film demonstrated the strongest antioxidant activity, as well as the best antibacterial and preservation effects. These results suggest that the SR-EO antibacterial composite film holds potential application value in the field of strawberry packaging.