Chitosan for food packaging: Recent advances in active and intelligent films

This review describes the most common methods for recovery of chitin from marine organisms. In depth, both enzymatic and chemical treatments for the step of deproteinization are compared, as well as different conditions for demineralization. The conditions of chitosan preparation are also discussed, since they significantly impact the synthesis of chitosan with varying degree of acetylation (DA) and molecular weight (MW). In addition, the main characterization techniques applied for chitin and chitosan are recalled, pointing out the role of their solubility in relation with the chemical structure (mainly the acetyl group distribution along the backbone). Biological activities are also presented, such as: antibacterial, antifungal, antitumor and antioxidant. Interestingly, the relationship between chemical structure and biological activity is demonstrated for chitosan molecules with different DA and MW and homogeneous distribution of acetyl groups for the first time. In the end, several selected pharmaceutical and biomedical applications are presented, in which chitin and chitosan are recognized as new biomaterials taking advantage of their biocompatibility and biodegradability.

Amongst the natural polymers, chitin is the second most abundant, present mainly in fungi and exoskeleton of crustaceans. It forms a major part of the seafood waste as compiled and presented in this review and is de-acetylated to produce chitosan. Structure and properties of chitosan have been described. Biocompatible and biodegradable characteristics of chitosan have been well studied. In addition to the environmental sustainability associated with its use, the malleability of chitosan due to its reactive amino and hydroxyl groups, adds to its wide repertoire in usage through various modifications. Recent publications of chitosan and derivatives have been classified into its various applications in food, pharmaceutical, biotechnology, medical, textile, paper, agriculture and environmental applications. The abundance of chitosan and diversity in modifications can be effectively utilized in various applications leading to environmental friendly solutions as highlighted in this review.