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Chitosan is a multifunctional biopolymer that is widely used in the food and medical fields because of its good antibacterial, antioxidant, and enzyme inhibiting activity and its degradability. The biological activity of chitosan as a new food preservation material has gradually become a hot research topic. This paper reviews recent research on the bioactive mechanism of chitosan and introduces strategies for modifying and applying chitosan for food preservation and different preservation techniques to explore the potential application value of active chitosan-based food packaging. Finally, issues and perspectives on the role of chitosan in enhancing the freshness of food products are presented to provide a theoretical basis and scientific reference for subsequent research.

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Nitrite is one of the main pollutants in the water worldwide. In this study, we have applied the reverse suspension crosslinking methodology based on chitosan (CS) and Fe3O4 (FeO) to synthesize the novel magnetic nanomaterial of chitosan (CS-FeO). The physical and chemical properties of CS-FeO were further characterized by scanning electron microscopy, particle size distribution, thermogravimetry, fluxgate magnetometer, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. Results revealed that CS-FeO showed high thermal stability in the temperature ranging from 50 to 200°C. CS-FeO showed high crystallinity and magnetism and was easily and quickly separated from aqueous solution in the presence of an external magnetic field. The molecular structure of CS-FeO showed that the core-shell structure of CS-FeO was established with FeO as the core and CS as the shell. Furthermore, the adsorption rate of nitrite by CS-FeO reached 65.83 ± 0.76 % under optimal conditions. Moreover, CS-FeO showed high regeneration capability with Na2SO4 used as the eluent. Our study demonstrated evidently that CS-FeO can be potentially used to remove nitrite from drinking water sources and industrial wastewater, suggesting the promising future of the application of CS-derived magnetic nanomaterials in the areas of environmental protections.

A significant portion of the protein in food waste will contaminate the water. The chitosan/modified β-cyclodextrin (CS/β-CDP) composite membranes were prepared for the adsorption of bovine serum albumin (BSA) in this work to solve the problem of poor adsorption protein performance and easy disintegration by a pure chitosan membrane. A thorough investigation was conducted into the effects of the preparation conditions (the mass ratio of CS and β-CDP, preparation temperature, and glutaraldehyde addition) and adsorption conditions (temperature and pH) on the created CS/β-CDP composite membrane. The physical and chemical properties of pure CS membrane and CS/β-CDP composite membrane were investigated. The results showed that CS/β-CDP composite membrane has better tensile strength, elongation at break, Young’s modulus, contact angle properties, and lower swelling degree. The physicochemical and morphological attributes of composite membranes before and after the adsorption of BSA were characterized by SEM, FT-IR, and XRD. The results showed that the CS/β-CDP composite membrane adsorbed BSA by both physical and chemical mechanisms, and the adsorption isotherm, kinetics, and thermodynamic experiments further confirmed its adsorption mechanism. As a result, the CS/β-CDP composite membrane of absorbing BSA was successfully fabricated, demonstrating the potential application prospect in environmental protection.