Preparation, optimizations, and applications of (carboxymethyl cellulose)-chitosan polyelectrolyte composite films in food packaging: a review.

The development of new, environmentally friendly, and efficient food packaging materials has always been a research hotspot in food science. Carboxymethyl cellulose (CMC) and chitosan (CS) are two renewable, biodegradable, environmental-friendly, and bio-based materials, which are widely found in nature and have great environmental and economic values. However, the presence of carboxyl and hydroxyl groups in the structure of CMC makes it highly sensitive to water, and CS can only be dissolved in acidic systems and has insufficient rheological properties, which limits the application of these two materials in the field of food packaging. Recent studies have shown that the strong electrostatic interaction between polyanionic sodium CMC and polycationic CS can be used to form polyelectrolyte composite films, which can effectively make up for the shortcomings of the two, and at the same time synergize their respective strengths, and have unique properties and great application potential in the field of food packaging. This article reviews the research progress of CMC/CS polyelectrolyte composite films in recent years, including preparation methods such as solution casting, preparation conditions such as raw material ratios, post-preparation optimization measures such as adding active agents (e.g., essential oils), crosslinking agents (e.g., glutaraldehyde), inorganic fillers, and molecular grafting, and application fields, especially for food packaging. This article aims to provide a valuable reference for further research on CMC/CS polyelectrolyte composite films, and provide ideas and a basis for their application in food packaging and beyond.