An updated review on the modifications and food preservation applications of chitosan.

Chitosan is a modified natural biopolymer obtained through the deacetylation of chitin, which is primarily found in the shells of crustaceans. Chitosan has recently attracted a lot of attention due to its possible use in the chemical, medical and food and industries. Due to its distinct biological activities and functional properties, its applications in the food industry are especially noteworthy. Its antimicrobial properties and ability to form films makes the biopolymer a promising natural food preservative and coating material. Chitosan exhibits antimicrobial activity against a broad spectrum of foodborne microbes including fungi, yeast, both gram-negative and gram-positive bacteria. The antimicrobial ability, along with its film-forming properties have made chitosan a leading polymer for the development of active packaging that can prevent microbial growth and enhance food safety. In terms of optical characteristics, pure chitosan films are highly transparent in the visible light range, demonstrating high transmittance values. This feature is crucial for the consumer acceptance of the films. Moreover, chitosan-based films show excellent UV absorption, which helps protect food from lipid oxidation caused by UV radiation. The qualities, modifications and applications of chitosan in improving the shelf life and quality of a variety of foods, including seafood, poultry, vegetables, juice, rice cake, soyabean sprout, mayonnaise and etcetera are considered in this paper.