Chitosan is a natural, biocompatible, and non-toxic biopolymer derived from the partial deacetylation of chitin. Due to its unique properties, this polymer has broad applications in the food industry (as a food preservative coating), pharmaceuticals (drug carrier, wound dressing), and chemical industries (heavy metal adsorbent). The industrial production of chitosan predominantly relies on chemical methods, which involve the use of concentrated sodium hydroxide solutions under high-temperature conditions to remove acetyl groups from chitin. However, these methods face significant challenges, including high energy consumption, generation of pollutant wastewater containing sodium hydroxide, and a lack of precise control over the degree of deacetylation. In contrast, the biological production of chitosan using the chitin deacetylase enzyme—produced by certain insects, fungi, and bacteria—has emerged as an environmentally friendly alternative. This approach offers notable advantages, such as reduced energy consumption, elimination of chemical pollutants, and the production of chitosan with a controlled degree of deacetylation.

This review study was conducted to examine chitosan production methods (chemical and biological), analyze the advantages and disadvantages of each approach, and evaluate optimization strategies for the production process, particularly on an industrial scale. Through a systematic review of articles published in Scopus, PubMed, and ScienceDirect databases, relevant data on chitosan production methods, the efficacy of the chitin deacetylase enzyme, and emerging technologies in this field were analyzed.

The findings of this study revealed that although the chemical method remains the dominant industrial approach due to its high speed and low initial cost, its environmental consequences (e.g., annual generation of thousands of tons of alkaline wastewater) and inconsistent product quality are identified as its primary limitations. In contrast, the chitin deacetylase-based biological method, despite challenges such as prolonged processing time and high enzyme production costs, exhibits significant potential for producing chitosan with tunable purity and physicochemical properties.