Relationships between chain length distribution of amylopectin and gelatinization properties within the same botanical origin for sweet potato and buckwheat

Starch samples from 51 sweet potatoes and 27 buckwheats with large variations in onset (To), peak (Tp) and heat (ΔH) for gelatinization determined by differential scanning calorimetry (DSC) were studied. Amylose content was found to be independent of all the DSC parameters. The quantitative molar distributions of the amylopectin chain length (DP 6–17) analyzed by high performance anion-exchange chromatography had a large influence on all the DSC parameters. It is concluded that, within the same botanical origin, an increase in short outer chains in amylopectin molecules reduces the efficiency of packing within the crystalline region of starch granules, resulting in lower To, Tp and ΔH.