PHYSICOCHEMICAL, MORPHOLOGICAL, THERMAL AND PASTING PROPERTIES OF STARCHES ISOLATED FROM RICE CULTIVARS GROWN IN INDIA

摘要

Physicochemical, morphological, thermal, and pasting properties of starches, isolated from basmati (HBC-19 and Bas-370) and non-basmati (Jaya, a coarse cultivar; P-44 and HKR-120, the medium cultivars and Sharbati, fine cultivar) rice cultivars grown in India were studied. The amylose content of starches from different cultivars ranged from 2.25 (Jaya) to 22.21 g/100 g of starch (HBC-19). Jaya, HKR-120, and P-44 cultivars showed soft gel consistency as 84, 73, and 69 mm, respectively, whereas Sharbati, Bas-370 and HBC-19 cultivars showed medium gel consistency as 54, 53, and 58 mm, respectively. Swelling power (at 95℃) indicated a significant positive correlation with amylopectin content (r = 0.828, p < 0.05) and gel consistency (r = 0.983, p < 0.01). Turbidity had a highly significant positive correlation with solubility (r = 0.919, p < 0.01) and amylose content (r = 0.945, p < 0.01). Starch form Jaya cultivar showed the presence of smallest size granules (2.4-5.7 μm) with an average size of 3.96 μm, whereas Bas-370 showed the presence of largest size granules (3.3-6.7 μm) with an average size of 5.0 μm. The transition temperatures, enthalpy of gela-tinization (△H_(gel)), peak height index (PHI) and gelatinization range were determined using differential scanning calorimetry (DSC). The starch from Sharbati cultivar showed highest onset temperature (T_o), peak temperature (T_p), conclusion temperature (T_c), enthalpy of gelatinization and peak height index (PHI) of 68.8℃, 73.2℃, 79.0℃, 11.56 J/g and 2.63 respectively. Pasting temperature of rice starches varied from 68.9℃ (Jaya) to 74.5℃ (Sharbati). The peak viscosities observed were in the range of 2223 to 3297 cP, lowest for HBC-19 starch and highest for Jaya starch.