Abstract:
Parboiling is the hydrothermal treatment applied before milling in order to increase milling recovery by minimizing
broken rice percentage at the end. Parboiling process has three stages namely soaking, steaming and drying. Soaking
' and steaming play a key role in quality of paddy grains by changing physical properties. Therefore, determination end
product quality is important. Effect of soaking and steaming duration was investigated with respect to head rice yield
in parboiling process. Paddy samples were given with different treatments of various degree of soaking and steaming,
Soaking and steaming conditions were kept constant for all treatments. Treatments were replicated three times. Lab
scale de-husking, milling and polishing machines were used to evaluate the head rice yield and broken rice yield
percentages. Lab scale detectors were used to count whiteness value, which reflected the appearance of final
processed product. Results obtained from the treatments, 72h of soaking with steaming for 3h duration, yielded
higher de-husked head rice recovery and less percentage of broken rice of85.3% and 14.7% respectively. The results
revealed that 3h steaming duration produced very less whiteness value of 10.4. While soaking and steaming duration
was increased the paddy samples also gave good recovery of head rice yield and whiteness values. There was no
significant difference among the treatments in head rice yield and whiteness value in the highest level. Therefore it is
concluded that in parboiling process parameters of soaking and steaming method and duration has to be optimized to
end up with quality processed rice through.
