Research on the Relationship between the Amylopectin Structure and the Physicochemical Properties of Starch Extracted from Glutinous Rice

Glutinous rice has very low amylose content and is a good material for determining the structure and physicochemical properties of amylopectin. We selected 29 glutinous rice varieties and determined the amylopectin structure by high-performance anion exchange chromatography with the pulsed amperometric detection method. We also determined the correlation between amylopectin structure and the physicochemical properties of starch extracted from these varieties. The results showed that the amylopectin chain ratio sigma degree of polymerization (DP) <= 11/sigma DP <= 24 of 29 glutinous rice varieties was greater than 0.26, signifying that these varieties contained type II amylopectin. The results of the correlation analysis with gelatinization temperature showed that sigma DP 6-11 was significantly negatively correlated with the onset gelatinization temperature (GT) (T-O), peak GT (T-P), and conclusion GT (T-C). Among the thermodynamic properties, sigma DP 12-24 was significantly positively correlated with To, Tp, and Tc, sigma DP 25-36 was significantly negatively correlated with To, Tp, and Tc, and sigma DP >= 37 had no correlation with the thermodynamic properties. The results of correlation analysis with RVA spectrum characteristic values showed that sigma DP 6-11 was significantly negatively correlated with hot paste viscosity (HPV), cool paste viscosity (CPV), consistency viscosity (CSV), peak time (PeT), and pasting temperature (PaT) among the Rapid Visco Analyzer (RVA) profile characteristics, sigma DP 12-24 was significantly positively correlated with HPV, CPV, CSV, PeT, and PaT, and sigma DP >= 25 had no correlation with the viscosity characteristics. Therefore, we concluded that the amylopectin structure had a greater effect on the T-O, T-P, T-C, Delta H and peak viscosity, HPV, CPV, CSV, PeT, and PaT. The glutinous rice varieties with a higher distribution of short chains and a lower distribution of medium and long chains in the amylopectin structure resulted in lower GT and RVA spectrum characteristic values.