Enhancing the functionality and pH responsiveness of anthocyanin-based intelligent packaging for food quality...

Anthocyanins, naturally occurring flavonoid pigments, have attracted substantial interest for intelligent food packaging due to their pronounced halochromic behavior, antioxidant activity, and biocompatibility. This review critically evaluates recent advances in green extraction technologies, including ultrasound-, microwave-, enzyme-, pulsed electric field-, and supercritical fluid-assisted extraction, with emphasis on their effects on anthocyanin yield, structural integrity, and pH-responsive performance. Furthermore, the influence of polymer matrices and fabrication techniques (e.g., solvent casting, layer-by-layer assembly, and electrospinning) on film microstructure, physicochemical properties, and sensing behavior is systematically discussed. Material engineering strategies, including copigmentation, inclusion complexation, nanoencapsulation, and metal-organic framework immobilization, are systematically evaluated for their roles in enhancing color stability, pH and volatile amine sensitivity, controlled release, and multifunctionality. Environmental and safety aspects, including migration behavior, biocompatibility, biodegradability, and regulatory considerations, are also critically assessed to facilitate industrial implementation. Overall, this review establishes a comprehensive structure-property-performance framework linking anthocyanin chemistry, extraction processes, material engineering, and sensing functionality, thereby providing strategic insights for the rational design and commercialization of next-generation intelligent packaging systems for real-time food freshness monitoring.