A review on the chemical modification of alginates for food research: Chemical nature, modification methods, product types, and application

Alginates have been widely applied and explored in many fields due to their significant advantages. Due to the presence of free hydroxyl and carboxyl groups, alginates can be easily modified by different chemical modification methods. The development and use of chemically modified alginates is one of the hotspots in the field of food science. This paper first summarized the molecular chemical nature of alginates. Then, this paper reviewed the chemical modification methods of alginates. Third, this paper analyzed the product types of chemically modified alginates. Fourth, this work discussed the food application of chemically modified alginates. Finally, this paper provides a summary and outlook of the chemically modified alginates for food research. The chemical modification methods can be classified into five types: ionic complexation with cationic substances, covalent bond modification of the hydroxyl groups, covalent bond modification with the carboxyl groups, step-by-step covalent bond modification, and synergistic modification of covalent bond methods with ionic complexation. The product types are dependent on their roles as minor (emulsions and model foods) or main (foams, fibers, spheres, films, 3D printed scaffolds, and environment-determined hydrogels) components. The food application can be classified into five types: functional active substances, gelling agents, emulsifying agents, materials for food encapsulation, and materials for food packaging and preservation. This paper can guide the research and development of chemically modified alginates for food research.