Physicochemical characterization of starch from Peruvian sweetpotato selections

Laboratory starches, isolated from seven sweetpotato selections grown at two locations in Peru, and commercially available Peruvian starch were characterized with regard to physicochemical properties. Chemical analyses included determination of nitrogen, ash, and amylose content. Physical characterization was based on results from differential scanning calorimetry (DSC), swelling power, solubility, and rheology of the pastes. We found that nitrogen and amylose content were not affected by location or selection, while ash content was affected by location. Results from the DSC analysis showed that selection identity (SI) did not affect DSC enthalpy, onset, peak, and final temperatures. Location affected only peak temperature. Investigation of starch swelling power showed that SI and location did not affect swelling power above 75 degrees C, and that laboratory starch samples had greater swelling power than commercial samples. Solubility was affected by location, but not by SI. Maximum viscosities of heated starch slurries were not affected by SI or location. Although laboratory and commercial samples did not differ significantly in chemical composition, physical behavior of their pastes was significantly different.