Structure, function and food applications of carboxymethylated polysaccharides: A comprehensive review

Background: Polysaccharides, a major class of biomacromolecules, are known as ideal raw food supplements for health food due to their few side effects. Meanwhile, they are often used to change physicochemical and textural properties of food products in food industries. Carboxymethylation processing is increasingly used in the modifications of polysaccharide functionalities. Carboxymethylation introduces carboxymethyl functional groups into polysaccharides, which causes changes in the physicochemical properties and structure of polysaccharides, thus improving and even adding new bioactivities of polysaccharides for food applications. Scope and approach: The review summarizes the recent progress about carboxymethylated polysaccharides, including i) synthetic methods, ii) structural characterization, iii) related bioactivities and structure-activity relationships, iv) mechanisms of action bioactivities, and v) food applications and safety evaluation. Key findings and conclusions: Structure of polysaccharides was changed after carboxymethylation, leading to the changes of their physicochemical and biological properties. Their bioactivities rely not only on the source of the polysaccharide but also on chemical structural features, such as degree of substitution, which was influenced by reagent concentration, reaction, solvent temperature of carboxymethylation. The carboxymethylated polysaccharides have been used in various fields of food application, such as food auxiliary agents, food packaging, carrier of food bioactive ingredients, sensors for analysis of food, functional food. Overall, Carboxymethylation has great potential to be used in food industries for improved functionalities of polysaccharides.