Carboxymethyl chitosan: Synthesis, functional properties, and applications in sustainable food packaging material.

Global environmental concerns about non-degradable packaging materials are increasing. Carboxymethyl chitosan (CMCS), a polysaccharide widely used in the food industry, has gained attention in the field of food packaging. Due to its biodegradability, film-forming ability, and biocompatibility, CMCS has emerged as a sustainable option for degradable and functional food packaging materials, offering solutions to plastic pollution and food waste issues. This review explores CMCS as a food packaging and delivery material, detailing its synthesis methods, optimal preparation conditions, functional properties post-carboxymethylation, and applications in the food industry, alongside safety assessments. It summarizes the physicochemical interactions of CMCS-based composites and their impact on relevant properties, highlighting CMCS's potential as a green strategy for smart and active food packaging materials. Additionally, it presents the latest advancements in CMCS applications in the food industry over the past decade. CMCS exhibits good biocompatibility and antibacterial properties, and its functionality in food packaging films and delivery materials is enhanced through functional modification and polymerization. CMCS is widely used as a matrix for food preservation films or coatings and as a carrier for active ingredients, thereby improving the encapsulation efficiency and storage stability of functional food components. This review comprehensively outlines the applications of CMCS in the food industry, filling gaps in the existing literature, and laying a theoretical foundation for the development of CMCS technology. It provides a reference for further research, emphasizing the need to further investigate its molecular structure and chemical properties to optimize functionality and safety, thereby fully tapping into the potential of CMCS in the food industry.