Chitosan-based films and coatings for active and intelligent food packaging: Formulation strategies, sensing mechanisms, and quality monitoring

Conventional plastic-based food packaging has excellent barrier and mechanical properties; however, its consistent waste generation has pushed the transition toward biodegradable alternatives with enhanced functionality. The review summarizes new advancements in chitosan-based biomacromolecules as intelligent packaging systems that protect food while conserving quality and safety changes through on-package indication. First, this review provides a concise overview of the primary structure and characteristics of chitosan, including its inherent antimicrobial activity, biodegradability, film-forming capacity, and cationic character. Then, this article discusses how these characteristics facilitate the development of multifunctional films and coatings. The most intelligent packaging techniques and their mechanisms explored include time-temperature indicators, pH- and freshness-responsive systems, spoilage and gas indicators, moisture-sensitive devices, and innovative optical and electrochemical biosensors that provide improved sensitivity and detection. The review also encompasses formulation and engineering strategies intended for enhancing the performance of chitosan-based films and coatings, including biopolymer blending, nanomaterial incorporation, bioactive compounds encapsulation, and cold plasma and irradiation assisted surface modification. Moreover, a detailed review is carried out on the key challenges limiting its commercial adaptation, notably moisture sensitivity, signal instability under real storage conditions, mechanical durability, standardized calibration against spoiling indicators, and regulatory safety concerns. The future perspective for the scalability and affordable utilization of chitosan-based intelligent packaging in food systems is also discussed.