Effect of variable parboiling on crystallinity of rice samples

Rice parboiled at various combinations of soaking temperature and steaming time were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Generally, gelatinization enthalpy decreased as the soaking temperature increased from 30 degrees C to 50 degrees C and 70 degrees C to 90 degrees C, and gelatinization enthalpy decreased as steaming times increased from 4 and 8 min to 12 min. As expected, a distinctive A-pattern was observed in the XRD of raw rice. The most severely parboiled laboratory sample (90 degrees C for 12 min), showed no discernable change toward the V-pattern. Crystallinity decreased from the raw rice (24.6%) with increased cooking temperature.