Functional biopolymers for food packaging: Formation mechanism and performance improvement of chitosan-based composites

Due to global environmental concerns and increased awareness of renewable green resources, many efforts have been made to use chitosan as a sustainable polymer to develop environmentally friendly food packaging materials. Although the low mechanical stability and high water sensitivity of pure chitosan films have limited its industrialisation, two active groups in chitosan monomers, i.e. amino and hydroxyl groups, help to form a variety of derivatives with improved performance, thus expanding the advanced applications of chitosan materials. This review has provided an insight into the network interactions of chitosan and its widely compounded components, highlighting the implications for performance improvement as food packaging. An obvious improvement was shown in the antimicrobial ability. Meanwhile, composites with variable interactions allow the formation of films with mechanical properties represented by superior tensile strength and elongation compared to many conventional polymers. The effect on gas barrier properties has also been demonstrated. The advances in the preparation methods and application of chitosan films are also discussed in the work. As a result, more efforts are needed in the future to develop chitosan-based food packaging with advanced performance.