Preparation of Polyvinyl Alcohol/Chitosan/Antrodia cinnamomea Polysaccharide Composite Film Incorporated with Tea Tree Essential Oil: Structure, Antioxidant, Antibacterial Activities, and Application in Postharvest 'Yuluxiang' Pear Preservation.

Polyvinyl alcohol (PVA)/chitosan (CS)-based films incorporated with Antrodia cinnamomea polysaccharide (ACP) and tea tree essential oil (TTEO) were developed using a solution casting method. The physicochemical, bioactive, and structural attributes, as well as the effects of these films on post-harvest 'Yuluxiang' pears, were assessed. The results demonstrated strong interactions among all functional components. The integration of ACP reinforced the mechanical properties of PVA/CS-based films, whereas the combined incorporation of ACP/TTEO enhanced water resistance, ultraviolet-light shielding ability, and barrier performance against oxygen and water vapor. Contact angle measurements showed that the PVA/CS/ACP/TTEO composite film exhibited superior wettability and adhesion to pear surfaces. Furthermore, the PVA/CS/ACP/TTEO composite film exhibited potent antibacterial activity, recording 99.99% inhibition against Staphylococcus aureus and 99.91% against Escherichia coli. TGA and DTG analyses suggested that ACP improved the thermal stability and restricted the film's degradation rate. Antioxidant assays revealed that the incorporation of ACP and TTEO markedly elevated the antioxidant ability of the PVA/CS-based film. After 21 days of storage, the PVA/CS/ACP/TTEO composite film effectively maintained firmness, titratable acidity, vitamin C levels, and the activities of superoxide dismutase and catalase in post-harvest pears. Moreover, the composite film delayed fruit yellowing and oiliness, lowered the accumulation of hydrogen peroxide and malondialdehyde, and significantly reduced microbial counts (p < 0.05). This study demonstrates that the fabricated PVA/CS/ACP/TTEO composite film possesses the ability to extend the shelf life of perishable fruits under ambient storage conditions.