Starch properties of new sweet potato lines having low pasting temperature

Abstract

Some new sweet potato lines were developed from progenies of a new cultivar, Quick Sweet, having a low pasting temperature. Starch granules from these lines demonstrated an abnormal morphology characterized by cracking into fragments. Starch and amylose contents were different among these lines. Pasting temperatures of these lines determined by the Rapid Visco Analyser were 53.8 to 66.6°C, i.e. 10 to 20°C lower than that of the control. Peak viscosities of some lines were similar to that of the control. Starch retrogradation, evaluated by percentage of leaked water and hardness of starch gels after cold storage, revealed that the control starch retrograded during storage for two to six weeks, but the starches of some lines retrograded much more slowly than the control starch and exhibited excellent cold storage stability. The pasting temperature had significant positive correlations with the percentage of leaked water and the hardness. These results indicate that Quick Sweet is a useful breeding material for improving pasting and retrogradation properties in sweet potato starch.