Digestive and Physicochemical Properties of Small Granular Starch from Euryale ferox Seeds Growing in Yugan of China

In this study, the morphological, physicochemical and digestibility properties of Yugan Euryale ferox seeds starch (Y-EFS) were comprehensively analyzed. The results showed that Y-EFS contained 45.85% amylose. These starch granules of Y-EFS appeared as irregular polyhedron shape with smooth surface and relatively uniform size around 2.29 μm. The determined average molecular weight of Y-EFS were 1.85 × 105 and 3.00 × 103 Da, respectively. X-ray diffraction verified that Y-EFS was a typical A-type starch with 38.84% relative crystallinity, which demonstrated that Y-EFS had a relatively high crystallinity and larger crystallization area. Differential scanning calorimeter analysis showed that Y-EFS had relatively high gelatinization enthalpy (ΔH = 1576.0 J/g) and temperature (To = 84.69 °C, Tp = 110.30 °C and Tc = 118.10 °C). The results of rapid viscometer analyzer demonstrated that pasting temperature of Y-EFS was 82.27 °C, and high setback value indicated that Y-EFS was possibly easy to retrograde. Y-EFS gel displayed small adhesiveness and high hardness. In vitro digestion study showed that Y-EFS was indigestible because of its 37.54% slowly digestible starch and 36.46% resistant starch content. Our results suggest that Y-EFS has great application prospect in hypoglycemic functional foods.