Physicochemical characterizations of three unconventional sources of starch from the Andean region in Ecuador

The physicochemical aspects of three native Andean starches from cultivars Arracacha xanthorriza, Canna edulis, and Oxalis tuberosa were investigated. Scanning electron microscopic investigations showed that the granular size s were remarkably different among the three starches. The starch granules o f A. xanthorriza were irregular, with granular sizes between 7-23 mu m wher eas the granules of O. tuberosa and C. edulis both were oval-shaped with gr anular sizes between 22-25 mu m and 35-101 mu m, respectively. All three st arches revealed an X-ray diffraction pattern of the B-type that also is rep orted to be typical for most kinds of tubers. The gelatinization enthalpies were 14.6 +/- 0.2 J g-l for O. tuberosa, 15.7 +/- 0.2 J g-l for C. edulis, and 17.6 I 0.3 J g-l for A. xanthorriza, and the peak temperatures of endo thermic differential scanning calorimetry (DSC)-transitons were 55.9 +/- 0. 2 degrees C, 61.2 +/- 0.1 degrees C, and 60.1 +/- 0.1 degrees C, respective ly. There were no direct correlations between the gelatinization parameters and the amylose content that was found to be 4 +/- 1% for A. xanthorriza, 18 +/-: 1% for O. tuberosa, and 24 +/- 0.4% for C. edulis.