Innovative preparation, physicochemical characteristics and functional properties of bioactive polysaccharides from fresh okra (Abelmoschus esculentus (L.) Moench)

Abstract In this study, three-phase partitioning (TPP) coupled with gradient ammonium sulfate ((NH4)2SO4) precipitation (GNP) method was first used to extract and separate bioactive polysaccharides (OPSs) from fresh okra pods. Results showed that OPS-50 obtained by GNP at a saturation of 50% (NH4)2SO4 after TPP presented higher precipitation yield, carbohydrate (86.82%) and uronic acid (22.34%) contents with same monosaccharide composition and different molar ratios compared with OPS-30 and OPS-40 obtained via GNP at saturations of 30% and 40% (NH4)2SO4, respectively. OPS-50 had lower weight-average molecular weight (3.65 × 106 g/mol), more flexible chain, and relatively looser surface structure compared with OPS-30, OPS-40, and the OPS obtained with TPP parallelized with decreased apparent viscosity and dynamic viscoelasticity. Furthermore, OPS-50 exhibited stronger DPPH radical-scavenging ability, antioxidant capacity, and α-amylase and α-glucosidase inhibitory activities in vitro than OPS, OPS-30, and OPS-40.