In
order to prepare amylopectin with typical characteristics, amylopectin
fractions isolated from mung bean, pea, cassava, sweet potato, potato,
maize, and wheat starch were cocrystallized with sodium oxalate, and
their physicochemical properties were investigated by optical microscopy,
molecular weight and chain length distribution, X-ray diffraction,
visible light absorption, and DSC. The results showed that all the
cocrystals with a dendritic shape consisted of a barbell-shaped center
and several large branches. After 72 h of eutectic process, the maximum
visible light absorption wavelengths of all amylopectin turned to
around 592 nm. In addition to pea and potato amylopectin, the eutectic
process for 72 h increased the molecular weight of the other five
amylopectin species, and the components of mung bean amylopectin were
changed from two to one during the eutectic process. Cocrystallization
narrowed the chain length distribution of all amylopectin chains,
with the mung bean amylopectin side chains being the shortest. The
X-ray diffraction results indicated that amylopectin may be complexed
with sodium oxalate. All the cocrystals displayed two separate small
endothermic peaks, with Tp around 97 °C and that above
170 °C related to the gelatinization of amylopectin segments
within cocrystals and the dissociation of sodium oxalate/amylopectin
complex, respectively. The formulation of cocrystals will be a promising
strategy to tune the physicochemical properties of amylopectin.