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 composite film (CS-BRA-PEP) was fabricated by incorporating Phyllanthus emblica L. polysaccharides (PEP) and black rice anthocyanins (BRA) into a chitosan matrix to develop a multifunctional and biodegradable packaging material for food preservation and freshness indication. The composite film integrates PEP and CS to encapsulate anthocyanins. Such architecture significantly improved the stablity of BRA while simultaneously conferring excellent pH-sensitivity properties to the film, making it a suitable real-time freshness indicator. In addition, the film showed excellent biocompatibility, antioxidant and antibacterial activity. Physicochemical analysis further revealed that the film possessed uniform morphology, improved tensile strength, and reduced water solubility, indicating enhanced structural stability and suitability for food packaging environments. When applied to the packaging of blueberries and shrimp, the film not only prolonged shelf life but also provided a clear visual indication of spoilage. To further realize the automatic identification and analysis of the pH response results of the proposed films, this study further introduced the advanced YOLOv8 model and developed a detection system to accurately reflect the freshness status of ingredients. The above study proved the CS-BRA-PEP film as a promising green material for intelligent food packaging, offering a sustainable solution that integrates preservation performance with visual freshness indication.