Molecular structure and characteristics of phytoglycogen, glycogen and amylopectin subjected to mild acid hydrolysis

The structure and properties of phytoglycogen and glycogen subjected to acid hydrolysis were investigated using amylopectin as a reference. Degradation occurred in two stages and the degree of hydrolysis followed the order: amylopectin > phytoglycogen > glycogen. Upon acid hydrolysis, the molar mass distribution of phytoglycogen or glycogen gradually shifted to smaller, broader distributions, whereas amylopectin changed from bimodal to monomodal. Kinetic rate constants for depolymerization of phytoglycogen, amylopectin, and glycogen were 3.45 × 10⁻⁵/s, 6.13 × 10⁻⁵/s, and 0.96 × 10⁻⁵/s, respectively. Acid treatment decreased particle radius, reduced α‑1,6 linkages, and increased rapidly digestible starch fractions. Depolymerization models were built to interpret structural differences among branched glucose polymers during acid treatment, guiding improved structural understanding and precise application of branched glucans with desired properties.