The steps to refine rice bran oil are as follows:
1. Degumming: This is the process of removing phospholipids from the crude rice bran oil. This can be done by adding ethanolamine or enzymes to the oil and stirring it at room temperature for some time. Then the oil is centrifugally separated to obtain coarse rice bran oil.
2. Pre-Bleaching: This is the process of reducing the color and impurities of the oil by adding bleaching earth to the oil and transferring it to the bleacher. The bleaching earth absorbs the unwanted substances and makes the oil lighter in color.
3. Dewaxing: This is the process of crystallizing and filtering the wax from the oil. The oil is cooled slowly and steadily in a special tower or a crystallizer, where the wax forms solid or slurry particles. Then the oil is passed through a filter press to separate the wax from the oil.
4. Neutralization: This is the process of reducing excess free fatty acid (FFA) from the oil by adding alkali or acid to the oil and stirring it. Then the soapstock (the mixture of FFA and alkali or acid) is separated from the oil by centrifugation or settling.
5. Decolorization: This is the process of further decreasing the color of the oil by adding activated clay to the oil and heating it. The activated clay absorbs more pigments and impurities from the oil and makes it clearer and transparent.
6. Deodorization: This is the process of removing unpleasant odors from the oil by injecting steam into the oil under high temperature and vacuum. The steam carries away the volatile compounds that cause odors and leaves behind a refined rice bran oil with a mild flavor.
These are the main steps of rice bran oil refining process.