Structural and functional characterization of pectic polysaccharide fractions isolated from Choerospondias axillaris...

This study sequentially extracted water-soluble pectin (WSP), chelate-soluble pectin (CSP), and Na₂CO₃-soluble pectin (NSP) from Choerospondias axillaris fruit flesh. Among them, WSP showed the highest yield (8.73%), while NSP exhibited the highest molecular weight (710 kDa) and contained the greatest levels of protein (11.89%) and polyphenol (2.70%). Arabinose and galactose were identified as the predominant neutral sugars. FTIR and NMR spectroscopy analyses indicated WSP had the highest esterification degree (68.87%). Structural characterization by SEM showed distinct surface morphology, with WSP displaying filaments and CSP exhibiting lamellar stacking. Further analysis using SAXS and AFM showed higher molecular order in WSP and CSP, whereas NSP adopted a more disordered and flexible conformation. Functionally, NSP demonstrated the greatest thermal stability, while WSP displayed the highest viscosity in rheological measurement. Together, these significant physicochemical and functional differences among the pectin fractions underline their distinct potential for targeted applications in functional foods and nutraceuticals formulations.