Chitosan–citric biomembranes Ch-CA-Gx (x = 0–3) were prepared by a simple cross-linking. The dependence of mechanical property, water-resisting capacity, microstructural characteristic, oxygen barrier ability, and thermal properties of membranes on the content of glycerin was investigated. The results revealed that vacuum drying at 80 °C can lead to low-yield amidation and the Maillard reaction, thus affecting the thermal stability and water resistance of biomembranes. Owing to the ionic cross-linking and amidation, the chitosan–citrate complex showed weaker compatibility when the glycerin content increased, thereby leading to discontinuity of microstructure in the Ch-CA-Gx (x = 1–3) membranes, which was in line with the weaker mechanical properties and water-resisting abilities of membranes, compared to Ch-CA-G0. Chitosan membranes showed interestingly high oxygen barrier capabilities under 40 and 80% relative humidity (RH) conditions, probably attributed to the increased diffusion length arising from the hydrogen-bonding, ionic, and covalent cross-linking. The oxygen transmission rates of Ch-CA-Gx were below 0.1 cm3 m–2 day–1 at 40% RH. The Ch-CA-Gx membranes showed a good elasticity assigned to the reversibly cross-linked structure. The membranes presented strong antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria, probably owing to the citric acids. The results demonstrated that these materials have potential applications as membranes or protecting coatings for food packaging and successful cross-linking by means of amidation, and the Maillard reaction under the condition of vacuum drying can be probably applied as a green and alternative method for the fabrication of mechanically tough and antibacterial membranes, fibers, and gels.

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Polyvinyl acetate (PVAc) and curcumin (Cu) were utilized for preparing new protecting PVAc−Cu x (x = 1, 5 and 10) coatings exerting antimicrobial photodynamic activity upon white light irradiation. Toward Salmonella typhimurium or Staphylococcus aureus, the killing efficiency represented the dependence on the Cu concentration and irradiation intensity. Toward S. aureus, the killing efficiency of PVAc−Cu 10 coating reached 93% at an energy density of 72 J/cm 2 . With the change in storage time of coating, the results implied significant stability of photosterilization efficiency within 60 days. Compared with the control experiment, lower total viable counts (TVCs) and total volatile basic nitrogen (TVB-N) values in fresh meat packaged by PVDC films with PVAc−Cu 10 coatings during storage at 4 °C demonstrated the practicability of the PVAc−Cu x coatings in decontaminating fresh pork. PVAc packed curcumin tightly within polymer chains, thus preventing tautomerization or, more probably, conformational transition, which is advantageous for improving photostability and emission lifetime.

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