Amylopectin—properties and fine structure

Five amylopectins from different sources were studied to compare their physico-chemical properties and structure. Physicochemical properties such as iodine binding capacity (IBC), maximum absorption (λmax) and intrinsic viscosity ([η]) were assayed. Normal corn amylopectin and potato amylopectin gave high values of IBC whereas waxy corn, corn commercial and amaranth exhibited low values of this parameter; all values for λmax were in the range 525–595 nm and those for [η]varied from 23 to 104 ml/g. Results suggested structural differences in the amylopectins. These macromolecules were eluted by high-performance size exclusion chromatography (HPSEC) with refractive index (RI) showing different elution times, which indicate structural differences among such components. The five amylopectins were debranched with isoamylase and pullulanase, and the fractions, studied both by HPSEC with RI and by high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD), showed structural differences among amylopectins and differences in debranched patterns of isoamylase and pullulanase.