Polyvinyl alcohol (PVA) has been widely applied in industries for its low cost, nontoxicity, biodegradability, and renewable advantages. However, its unstable structure may not meet some strong physical and mechanical needs. In order to enhance the performances of the PVA film, cellulose nanocrystals (CNCs), tannic acid (TA), and chitosan (CS), working as a reinforcer, a crosslinker, and an antimicrobial agent, respectively, were introduced into the PVA matrix. The results indicated that CNCs, TA, and CS were evenly distributed and cohesively incorporated within the PVA matrix, which contributed to the good mechanical properties and thermal stabilities of biocomposite PVA films. Besides, the addition of TA remarkably improved the antiultraviolet and antioxidant capabilities of PVA films, although the light transmittance declined slightly. It was also observed that the pure PVA film and PVA reinforced with CNCs were incapable of protecting against bacteria, while the ones with CS had prominent antibacterial properties to Escherichia coli and Staphylococcus aureus. Overall, the resulting film presented a high potential utilization as a food packaging material for its outstanding physical and mechanical performances.

Plant essential oils are widely used in food, medicine, cosmetics, and other fields because of their bacteriostatic properties and natural sources. However, the bacteriostatic range of unilateral essential oils is limited, and compound essential oil has become an effective way to improve the antibacterial properties of unilateral essential oils. In this study, based on the analysis of the antibacterial properties of Chinese cinnamon bark oil and oregano oil, the proportion and concentration of the compound essential oil were optimized and designed, and the antibacterial activity of the compound essential oil was studied. The results showed that the antibacterial activity of Chinese cinnamon bark oil was higher than that of oregano oil. The compound essential oil prepared by a 1:1 ratio of Chinese cinnamon bark oil and oregano oil with a concentration of 156.25 ppm showed an excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. The GC-MS results showed that cinnamaldehyde was the main antibacterial component of Chinese cinnamon bark essential oil, and carvacrol and thymol in oregano oil were the main antibacterial components.