| A type of antimicrobial packaging is antimicrobial coating packaging, which has been paid close attention due to the simple and easy to operate, the remarkable antimicrobial activity, security and economy and other advantages. Coating method was used to prepare chitosan/poly (vinyl alcohol) (CS/PVA) films and Nisin loaded chitosan/poly (vinyl alcohol) (Nisin-CS/PVA) films. In this paper, the structure and properties and diffusion kinetics and thermodynamics of films were characterized and tested. CS/PVA/MMT and SL-CS/PVA/MMT films were prepared and the structure and properties and diffusion kinetics of films were tested.CS/PVA matrix films were prepared by coating method.In films, CS and PVA were combined in the form of intermolecular hydrogen bond. Owing to the incorporation of PVA, mechanical strength of CS/PVA films was reduced and the elongation at break of CS/PVA films was significantly improved. Through the analysis of the mechanical properties of the films, the best property sample is the CS/PVA=1/1 film, which could be used to prepare the Nisin-CS/PVA antimicrobial film. Gas permeability of CS/PVA films could be significantly affected by the incorporation of PVA. Based on the experimental results above, we selected the substrate materials (CS/PVA=1/1, CS/PVA=2/1, CS/PVA=3/1) for diffusion experiments of Nisin of Nisin-CS/PVA films.Nisin-CS/PVA film was prepared with Nisin as antibacterial agent. The results showed that the releasing dosage of Nisin into bacterial suspension increased in quantity with the increase of the Nisin content in films, therefore, the growth of S. aureus was inhibited effectively; while the content of Nisin was 10%, the antibacterial effect of film was best. The diffusion mechanism of Nisin in Nisin-CS/PVA film could be described by Fick diffusion; the diffusivity of Nisin (D) increased with the increase of CS/PVA ratio, but Ea reduced as the increase of CS/PVA ratio. The diffusion efficiency was investigated as a function of pH and ionic strength. The thermodynamic parameters indicated that the diffusion process of Nisin from film was spontaneous and endothermic. From diffusion and antimicrobial activity results, Nisin-CS/PVA films revealed well controlled release and better antimicrobial activity against S. aureus.SL-CS/PVA/MMT film was prepared with SL as antibacterial agent. The intercalation structure was present in CS/PVA/MMT film (CS/PVA/MMT d001=1.697nm, MMT d001=1.270nm); the intermolecular hydrogen bond exist between CS and PVA. The CS/PVA/MMT film is effective in blocking the UV and visible light; surface color difference of films was partly affected by MMT content; gas permeability of CS/PVA/MMT films was significantly affected by MMT content.The releasing dosage of SL into bacterial suspension increased in quantity with the increase of the SL content in films, therefore, the growth of E. colid was inhibited effectively and the inhibition efficienty increased correspondingly. The diffusion mechanism of SL in SL-CS/PVA/MMT film could be described by Fick diffusion; the diffusivity of SL (D) increased with the decrease of pH, but the diffusivity of SL (D) decreased with the increase of NaCl concentration. |
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