Pasting and Thermal Properties of Potato and Bean Starches

Starches from potato (Mainechip, ND651‐9 and Commercial) and Navy and Pinto bean were isolated and the pasting and thermal properties examined. Analysis by Rapid Visco‐Analyzer (RVA) showed potato starches had lower pasting temperatures, higher peak viscosity, and lower setback than bean starches. High intrinsic viscosity values obtained for the potato starch indicated higher average molecular weight for the potato starches compared to the bean starches. Characterization of thermal (gelatinization and retrogradation) properties of starches by Differential Scanning Calorimetry (DSC) showed that potato starches had sharp, well‐defined gelatinization thermograms, while bean starches had broad, shallow thermograms with higher peak temperature (Tp). Potato starches required higher gelatinization enthalpies than bean starches. In comparison with gelatinization, the retrogradation thermograms of starches stored at three different temperatures (23,4 and −10°C) were broader and occurred at the lower temperatures. Compared to potato starches, Navy and pinto bean starches showed a higher retrogradation enthalpy at 4 and 23°C storage temperatures, but a lower enthalpy at −10°C.