RICE BRAN OIL EXTRACTION USING AN EXPELLER MACHINE

Abstract

A study was carried out to test and evaluate the effect of screw speed, clearance outlet, and steaming process on the extraction efficiency of rice bran oil using a proto type expeller. Four screw speeds of (30, 50, 70, and 90 rpm ), four clearanceoutlets (0.2, 0.4, 0.6 and 0.8 mm ) and two different bran conditions (raw and stabilized) were studied and evaluated. Both raw and stabilized bran were steamed for 35 min using a laboratory scale steaming unit. The evaluation system based an: extraction efficiency, machine capacity, and percentage of free fatty acids (FFA) in the extracted oil. The results showed that, steaming process increased themoisture content of raw bran from an initial level of 12.05 % to a final level of 14.52 % w.b, while it increased from an initial level of 6.99 % w.b. to a final level of 12.67 w.b. for the stabilized bran. Moreover, during the expression process, the bran moisture content gradually decreased with the increase of screw speed and the decrease of outlet head clearance. Meanwhile, the percentage of extracted oil decreased with the increase of the expeller screw speed, and outlet head clearance. While, the expeller capacity increased with the increase of screw speed and the outlet head clearance. On the other hands, the steaming process increased the extraction efficiency for both raw and the stabilized bran. While, the steamed stabilized bran showed a slightly lower extraction efficiency in comparison with the steamed raw bran. On the same time, the stabilized steamed bran showed lower percentage of free fatty acids and more storage stability of the extracted oil in comparison with the steamed raw bran.