Molecular structure of amylopectin from Amaranth starch and its effect on physicochemical properties.

The molecular structure of amylopectin and its varphi,beta-limit dextrins from starch of 13 amaranth cultivars was determined by HPAEC-PAD after debranching. Chain length profiles of amylopectins showed bimodal distributions. The molar-based ratios of the average chain lengths of amylopectins (CLap) ranged from 17.41 to 18.22. The molar-based average chain lengths (CLld) and average B-chain lengths (BCLld) of varphi,beta-limit dextrins varied from 7.68 to 8.05, and from 14.10 to 14.73, respectively. Correlation analysis indicated that most structural parameters were positively correlated with thermal properties with few exceptions, whereas the content of fraction fa' ("'" stands for molar-based chain length ratio) was negatively correlated with the thermal properties. Pasting properties of cold paste viscosity (CPV) and setback were also correlated with amylopectin structural parameters.