Rice bran oil is extracted from the hard outer brown layer of rice called bran. The process of extracting oil from rice bran involves several steps, including cleaning, de-stoning, husking, separation, and stabilization.
The time required to make rice bran oil depends on the extraction method and the processing steps involved. According to one study, the optimal conditions for extracting rice bran oil using ultrasound-assisted extraction were a solid–liquid ratio of 4:1, an extraction temperature of 40 °C, an extraction time of 35 min, and an oscillation speed of 180 r/min.
Under these conditions, the oil yield was 18.6%. However, other methods such as solvent extraction, supercritical fluid extraction, or enzyme-assisted extraction may have different extraction times and yields.
After the oil is extracted from the rice bran, it needs to be refined and separated into a clear liquid and a hard fraction. The rice bran oil refining process usually includes filtering, neutralization, degumming, decolorization, deodorization, and dewaxing. The refining time may vary depending on the equipment and the quality of the crude oil. Therefore, the total time to make rice bran oil can range from a few hours to several days.