Green in-situ synthesis of AgNPs on nanocellulose for intelligent packaging: antibacterial, antioxidant, and real-time freshness monitoring

Intelligent biodegradable biomass packaging can extend the shelf life of food and reduce waste by monitoring the quality of the food in real time. Fresh products are highly prone to spoilage and deterioration. Packaging materials that hinder the growth and reproduction of microorganisms and delay lipid oxidation are crucial for extending the shelf life. In this study, UV irradiation-induced AgNPs achieved in situ growth on natural nanocellulose substrates to confer long-lasting, potent antibacterial properties to the films. As irradiation duration increased, AgNPs aggregated. By doping with alizarin, the film exhibited excellent antioxidant properties and pH indicator characteristics. The CNF-AX film has high water vapor permeability, visible light barrier properties and mechanical properties. The composite film has an inhibition rate of over 98% against Escherichia coli and Staphylococcus aureus. Under CNF-AX packaging, the pH values, colony counts and volatile basic nitrogen indicators of pork and fresh shrimp changed significantly later than those of other packaging. This enabled the preservation period of pork and fresh shrimp to be extended by 2 days. Moreover, as the quality of the packaged contents changed, the film exhibited obvious color changes, demonstrating the potential for real-time monitoring of the contents of the packaging. The packaging developed in this research is both biodegradable and bio-friendly, and it also has antibacterial, antioxidant and real-time food quality monitoring functions. It provides a green and sustainable solution for related fields and demonstrates great potential for application in the fields of fresh food preservation and quality monitoring.