Rice Bran Oil Extraction by Screw Press Method: Optimum Operating Settings, Oil Extraction Level and Press Cake Appearance

The appearance of rice bran ‘cake’ or discharge from a screw press corresponds to the level of oil produced in the extraction process. The relationships between operating settings, oil extraction level and cake appearance were studied. Cake characteristics reliably indicate the expected oil recovery extraction level. These conclusions applyed to both Chainat 1 rice bran and parboiled rice bran. Variables were the speed of the screw press (set at five levels from 8.5 to 19.8 r/min) and corresponding clearance distances between the screw and barrel (set between 1.0 and 1.9 cm). Results showed that the maximum levels of extraction were 4.17% for the rice bran and 8.20% for the parboiled rice bran. At the maximum extraction level, the apparatus continuously discharged cake that were hard, crispy, flaky, shiny and polished on one side but dull and coarse on the other.