Effect of native crystalline structure of isolated potato starch on gelatinization behavior and consequently on glycemic response

Effect of crystalline structure of two isolated potato starches on gelatinization and glycemic response was studied. Both starches showed to possess different fine structures. Starch 1 exhibited a typical B-type X-ray diffraction pattern, while Starch 2 exhibited an X-ray diffraction pattern suggesting the presence of imperfections of the general B-type crystalline structure (peak at 5.5 degrees 2 theta was absent), hence disarraying the structure order. This difference was reflected in the gelatinization behavior and consequently in the glycemic response. Starch 2 started to melt at lower temperature than Starch 1 (e.g. T-o was 60.9 and 61.84 degrees C, respectively, to native starches), and residual gelatinization enthalpy (Delta H) of Starch 2 was always smaller than that of Starch 1 when heated at 54-65 degrees C for 10 min. Glycemic response was increased as gelatinization degree (DG) increased in starches independent from the native crystalline structure (area under curve = 2.59 x DG-75.83, R-2=0.986; maximum concentration of postprandial blood glucose=0.042 x DG-0.23, R-2=0.935). Results suggested that native crystalline structure of isolated potato starch affects the glycemic response of heated starches by affecting the gelatinization behavior. (C) 2011 Elsevier Ltd. All rights reserved.