Abstract: Alginate oligosaccharides (AOS), linear polymers which contain 2–10 sugar units, are made from the degradation of alginate. Studies have shown that AOS have diverse functional activities and thus have high potential for application in functional foods, biomedicine and green agriculture. The bioactivity of AOS is closely related to their molecular mass, ratio of mannuronic acid to guluronic acid residues and polydispersity. The emergence of physical, chemical, combined physical-chemical and biological techniques for the degradation of alginate provides a variety of alternative pathways for the controllable preparation of AOS, thus opening up a new perspective for the research and development of AOS. AOS can preserve the quality of fruit and vegetable by synergistically regulating the postharvest metabolism through multiple pathways. They significantly inhibit the postharvest deterioration of strawberries, kiwifruits, apples, peaches and pears, thereby extending the shelf life. Recent research shows that the preservation effects of AOS involves the regulation of the abscisic acid pathway, the activation of the jasmonic acid pathway, the inhibition of ethylene signals, the balancing of energy metabolism, the scavenging of free radicals and cellular structure protection. Therefore, this review summarizes recent advances in the structural regulation of AOS and the mechanism of their preservation effects on the postharvest quality of fruits and vegetables, and it analyzes the intrinsic relationship between the structural specificity of AOS and their preservation effect. This review hopes to provide a theoretical reference for the design and development of green biopreservatives based on AOS.

Key words: alginate degradation; oligosaccharide structure; preservation effect; molecuar mechanism; natural preservatives