Structural characterization of two poly-galacturonic acids: the important basis to elucidate spherical conformation of pectin from submicroparticles in chrysanthemum tea infusion

Abstract

Pectin exhibits potential as an excellent food additive for its processing properties and biological activities, but its application is hindered because of complex and unclear structure. Water-insoluble and water-soluble poly-galacturonic acids, hydrolyzed from the spherical pectin from submicroparticles in chrysanthemum tea infusion, were characterized for obtaining the detail structural information. The water-insoluble poly-galacturonic acid was a crystal which constructed by hydrogen bonds and long linear chains comprised of α-1,4-glycosidic bonds and galacturonic acid residues. The water-soluble poly-galacturonic acid was a sphere which constructed by hydrophobic interactions and short linear chains comprised of α-1,4-glycosidic bonds and galacturonic acid residues. The distribution of poly-galacturonic acid blocks in sugar chains might be the important basis for the flexibility and spherical conformation of pectin from submicroparticles in chrysanthemum tea infusion. The results added evidences to better understanding of primary structure and spherical conformation of pectin from submicroparticles in chrysanthemum tea infusion.

Keywords: Block polymer; Conformation; Homogalacturonan domain; Nuclear magnetic resonance analysis; Pectin; Primary structure.