Structural, thermal and rheological properties of starches isolated from Indian quinoa varieties

In this study starches isolated from Indian quinoa varieties were examined for physicochemical, morphological, thermal and rheological properties. Among isolated starches V₁ showed higher starch yield and lower purity (48.45% and 98.32%) than V₂ (41.28 and 98.53%). The amylose content was higher for V₁ (12.10%) than V₂ (9.46%). Swelling powers and solubility of the starches increased with increasing temperature. Peak viscosity (386.4 RVU) was higher for V₁. In contrast V₂ showed higher pasting temperature (72.85°C). Low setback viscosity of the starches suggests that they can be profitably used in frozen and refrigerated foods. Starch granules from both varieties were irregular, angular and polygonal in shape. The starch granule size obtained by SEM was 1.23μm for V₁ and 1.19μm for V₂. Both starches showed a typical A-type diffractrometric pattern with varying crystallinity. Further V₁ showed lower transition temperatures (To, Tp and Tc) than V₂. FTIR spectroscopy showed higher intensity and broader shape of V₂ at OH stretch which can be due to its higher crystallinity. Increased interest is shown in quinoa starch because of its unique microcrystalline granules. Higher yield and purity values suggest that both varieties can be exploited for commercial starch utilization.