Physicochemical properties and in vitro hypolipidemic activities of three different bonding state pectic polysaccharide fractions extracted sequentially from pear pulp.

In this study, water-soluble fraction (WSF), chelator-soluble fraction (CSF), and sodium carbonate-soluble fraction (NSF) were sequentially fractionated from pear pulp, of which physicochemical properties and hypolipidemic activities in vitro were evaluated. They showed distinct monosaccharide composition, surface morphology, nuclear magnetic resonance (NMR), and Fourier transform infrared (FT-IR) spectrums. WSF and NSF were identified as high methyl-esterified pectic polysaccharides with degrees of methyl esterification (DM) of 85.71 % and 66.67 %, respectively, whereas CSF was low methyl-esterified pectic polysaccharides (47.83 %). WSF, CSF, and NSF all demonstrated low molecular weight, desirable rheological, thermal, antioxidant, and hypolipidemic effects in vitro. It was remarkable that WSF displayed the most excellent inhibition capacity of cholesterol micelles (26.63 %), pancreatic lipase (PL) (91.13 %)/cholesterol esterase (CEase) (53.10 %) activity inhibition, attributed to its highest DM and roughest morphology. CSF and NSF exhibited stronger cholate-binding capacity than WSF, inseparable from higher apparent viscosity and gel ability. On these grounds, different bonding state pectic polysaccharide fractions from pear presented some distinctions in their structural characteristics and functional properties, which might endow them with exploitation in health promotion and dietary supplements.