Chitosan processing, modification, and multifaceted applications across food, pharmaceutical, and cosmetics industries

Abstract

Chitosan is a natural polymer obtained by the deacetylation of chitin to enhance its physical-chemical properties. Processing takes two main methods: chemical and biological. The chemical methods used in its extraction take the following steps: deproteinization, demineralization, deacetylation, and bleaching, while biological extraction methods use enzymes to remove protein and acetyl groups. While the chemical method is the principal one employed commercially, the enzymatic method has been used, resulting in chitosans with a non-random pattern of deacetylation. In the recent past, advanced processing techniques such as microwave, ultrasonic, pulsed electric field technologies, and deep eutectic solvent (DES) methods have been used in its extraction. This polysaccharide comprises randomly distributed β-(1–4)-linked d-glucosamine and N-acetyl-d-glucosamine in a repeating sequence. The functional groups in chitosan molecules make them easily adaptable for industry use, owing to their macromolecular structure, biocompatibility, non-allergenic, anti-bacterial, and non-toxicity properties, in addition to increasing their solubility in solvents and functionality. Modification of chitosan is to attain desired attributes for application in various industries. Modification can reduce the molecular size, incorporate a functional group, reduce the degree of acetylation, modify the pattern of acetylation, and reduce the polydispersity index, among other structure-function relationship-related factors. Chitosan has broader applications in food, wastewater treatment, soil conditioning, wound healing, cosmetic, biomedical and pharmacological uses.