Structure characteristics related to biological properties and application of chitooligosaccharides: Mini-Review

Chitooligosaccharides (COS) are degradation products after cleavage of β-1,4-glycosidic bonds from chitosan, which are converted and extracted from chitin in the shells of shrimp, crabs and other crustacean creatures. Degradation methods to obtain chitooligosaccharides include acids hydrolysis, oxidative cleavage, ultrasound oscillation, enzymatic catalysis, and the combination of two or more methodologies. Due to the low degree of polymerization of glucosamine units, chitooligosaccharides possess superior characteristics to chitosan and chitin, such as a lower molecular weight and higher aqueous solubility, translating more applicability in food and related products in particular. The primary amino groups at C-2 position of chitooligosaccharides are positively charged in weak acidic conditions and also readily derivatized with acylation, alkylation, carboxylation, esterification, Maillard reaction, protonation forming salts, and sulfation. Exploration of chitooligosaccharides biological activities revealed that they possess antibacterial, antioxidant, anti-inflammatory, and immunomodulatory effects. The major applications of chitooligosaccharides are in food packaging, functional films, hydrogels, emulsions and drug-loaded complex. This review aims to summarize chitooligosaccharide properties and their application in food related products.