Molecular characteristics and rheological properties of water-extractable polysaccharides derived from okra (Abelmoschus esculentus L.)

Abstract

Compositions, molecular characteristics, and rheological properties of the water-extractable polysaccharides from okra were investigated. The proportions of galacturonic acid and monosaccharides in the refined polysaccharides were 62.47% and 13.47%, respectively. The molecular weight distribution of 717.5 kDa in the crude polysaccharides was removed through a purification process. Okra polysaccharides were pseudo-plastic fluids exhibiting shear thinning behavior. The refined polysaccharides had a higher apparent viscosity (332.15 mL g−1) than the crude polysaccharides (294.69 mL g−1), and exhibited a positive linear correlation with the logarithm of the zero shear viscosity between 1.0% and 4.0%, showed an elastic behavior at a stress of 1 Pa over the frequency range of 1–10 rad/s. When the concentration reduced below 2.0%, the refined polysaccharides showed a predominantly viscous response over the same frequency range. The rheology was greatly affected by their concentrations, indicating water-extractable okra polysaccharides have great potential as a thickening agent in food industry.