الفهرس 
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Abstract
A study was carried out to test and evaluate two different types of oil extracting machine, hydraulic press unit and expeller machine for rice bran oil extraction under different pre-treatments of the bran and different operational conditions of the studied machines. For the hydraulic press method four different steaming periods ( 20, 25, 30, and 35 min) six applied pressures (150, 175, 200, 225, 250 and 275, bar) and four holding times (10, 15, 20 and 25, min) were examined for two different types of bran (raw and stabilized). However, for the modified expression machine, four levels of screw speed (30, 50, 70,and 90 rpm ) four levels of the press head clearance (0.2, 0.4, 0.6, and 0.8 mm), and two different types of bran were also tested for both raw steamed bran, and stabilized steamed bran. The results of hydraulic press unit showed that, the moisture content of bran samples (raw and stabilized) increased with the increase of steaming period. Meanwhile, the extraction efficiency of oil increased with the increase of steaming period, applied pressure and holding time. On the other hand, heat stabilization of bran samples prior to steaming process causes a slight reduction in percentage of the extracted oil. On the same time, it has showed a reduction in the percentage of free fatty acids which in turn keeps the extracted oil more stable during the storage process. Meanwhile, the results of expeller machine showed that, steaming process increased the bran moisture content. Meanwhile, the extraction efficiency of 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. However, the steamed stabilized bran showed slightly lower extraction efficiency in comparison with the steamed raw bran. On the same time, the stabilized steamed bran showed lower percentage of (FFA) and more storage stability of the extracted oil in comparison with the steamed raw bran.