Chemical characterization of single helical mung bean amylopectin

The distinctive chemical properties of amylopectin are attributable to the single and double helical structures that are characteristic of the polysaccharide. In the extant literature, amylopectin is generally described as a combination of these two structural forms, with limited studies focusing exclusively on the chemical properties of the single helical ones. In this paper, the single/double helical mung bean amylopectin (SMBA/DMBA) was prepared by the innovative methodology developed in-house and its chemical properties were characterized by molecular weight, chain length distribution, light micrographs, FT-IR、¹³C Solid-state NMR, XRD, and DSC. The results indicated that the primary branch diameter of SMBA aggregates was approximately half that observed in the double helical structure. Furthermore, the number-average molecular weight (Mn) of SMBA was found to be 123,538 g/mol, with a higher proportion of chains with 1, 10-13 glucose residues. The wavenumbers of 1022.6 and 1020.6 cm^-1 represented the amorphous structure composed of SMBA and DMBA, respectively. In comparison with DMBA, the resonances of carbon atoms, excluding C4, in SMBA exhibited a lower field shift. The diffraction angles of single-helix mung bean amylopectin were found to be 2θ at 17.54 ^o and 22.28 ^o. The findings of this study provide a reliable marker for the identification of single helix in starch and its influence on the properties of starch.