Elucidating the impact of enzymatic modifications on the structure, properties, and applications of cellulose, chitosan, starch and their derivatives: a review

Polysaccharides, as one of the most prominent natural biopolymers, display numerous biological activities and industrial applications. Nevertheless, some polysaccharides lack biological properties or display weak biological activities. Besides, practical usages of polysaccharides still remain challenging because of their poor solubility and inappropriate hydrophilic/hydrophobic balance. Hence, enzymatic or chemical modifications have been emerged to improve physicochemical and biological properties of polysaccharides by altering their structural and conformational features, and consequently to enlarge their industrial applications. Compared to chemical methods, enzymatic modifications have drawn more attention owing to decreasing the input energy and environmental pollution, as well as high specificity and selectivity. The present review describes different reactions, including hydrolysis, esterification, transesterification, polymer, and phenolics grafting, for the modification of cellulose, chitosan, starch and their derivatives by catalysis with free and immobilized enzymes. Beyond the reaction types and the enzymes, the properties and potential applications of the obtained products are also reviewed.