Multifunctional pH-responsive chitosan-based films incorporating Phyllanthus emblica L. polysaccharides and black rice anthocyanins for perishable food quality maintenance and intelligent freshness monitoring

A novel chitosan-based film (CS-BRA-PEP) has been developed, composed of <i>Phyllanthus emblica</i> L. polysaccharide (PEP) and black rice anthocyanin (BRA), serving as a multifunctional, biodegradable food preservation packaging material. The film enhances the stability of BRA by encapsulating it with PEP and CS. BRA imparts excellent pH sensitivity to the film, enabling real-time freshness indication. The film exhibits good biocompatibility, antioxidant properties, and antibacterial activity. Physicochemical analysis confirms its uniform morphology, high tensile strength, and low solubility, indicating enhanced structural stability in food packaging. In preservation experiments on blueberries and shrimp, the film, through synergistic effects of physical barrier, moisture regulation, antioxidant, antibacterial, and intelligent response mechanisms, reduces moisture loss, oxidative spoilage, and microbial growth, thereby extending shelf life by 30 h. An integrated detection system based on YOLOv8 achieved an automated freshness analysis accuracy of 98.5 % based on pH-response. CS-BRA-PEP is a potential green and smart packaging material that combines preservation and visual freshness indication functions.