Pectic oligosaccharides: enzymatic preparation, structure, bioactivities and application.

Pectic oligosaccharides have become novel bioactive components. However, the comprehensive preparation methods, structural features, bioactivities and application of them lack a systematic review. Here, we focused on the enzymatic preparation of pectic oligosaccharides, and attempted to outline relationships among the enzymolysis condition, structure, bioactivities and application of pectic oligosaccharides. Pectic oligosaccharides were characterized by the oligosaccharides with units of →4)-α-GalpA-(1→4)-α-GalpA-(1→ or →4)-α-GalpA-(1→2)-α-Rhap-(1→. Enzymatic method was the most suitable approach for pectic oligosaccharides preparation that was significantly affected by the enzyme's type, time and concentration. Besides, pectic oligosaccharides possessed various bioactivities including prebiotic, anti-glycosylation, antioxidant, anticancer and lipid metabolism-regulation activities, which were closely associated with the molecular weight, the structure of side chain and the monosaccharide composition. Especially, many pectic oligosaccharides with low molecular weight demonstrated high prebiotic activities, and those with arabinogalactan side chains exhibited strong anticancer activities. Moreover, pectic oligosaccharides have been used in food preservatives, dairy product additives and food processing aids. Nevertheless, the industrial application, novel technology exploration, and structure-bioactivity relationship of pectic oligosaccharides remain a demanding and significant task for future work.