COMPARISON OF PHYSICOCHEMICAL, THERMAL, PASTING AND MORPHOLOGICAL PROPERTIES OF WEED RICE AND RICE STARCHES

A novel starch was isolated from weed rice crop and its starch properties were compared with rice starch. The starch properties studied were physicochemical, pasting, thermal and X-ray diffraction. The amylose content and swelling power (g/g) of weed rice starch was 13.7% and 19.8 g/g, respectively. Light transmittance (%) of starch paste from weed rice was observed higher as compared to rice starches. Pasting properties (PV, TV, SB, and FV) of weed rice starch was within the range of those earlier reported for rice starches. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were evaluated by using differential scanning calorimetry (DSC). The values of T_o, T_p and T_c were 68.86, 77.45 and 82.05 °C, respectively, for weed rice. ΔH_gel value for weed rice starch was 3.80J/g which was significantly lower than that of rice starches (8.09-13.81J/g). X-ray diffractions behavior for both weed and conventional rice starches exhibited a typical A-type pattern which is normally reported for cereal starches. Weed rice starch was also studied for their morphological properties by using a scanning electron micrograph (SEM). SEM of weed rice starch revealed the presence of pores on the surface and varying in size and shape of starch granules from small to large and angular to polyhedral, respectively.