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ARS Home » Research » Publications at this Location » Publication #111964
Title: THERMAL GRADIENT DEACIDIFICATION OF CRUDE RICE BRAN OIL UTILIZING SUPERCRITICAL CARBON DIOXIDE

Author
item Dunford, Nurhan
item King, Jerry

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rice bran oil for food use has been commercially produced in the United States since 1994. Rice bran oil is rich in compounds called phytosterols, which have cholesterol-lowering properties. Worldwide consumption of rice bran oil is expected to increase due to its nutritional value. Conventional edible oil refining processes use large quantities of water and chemicals. Furthermore, a significant portion of the nutritive rice bran oil components is lost during the conventional refining process. In our previous study we developed an environmentally friendly refining process involving fractionation with high pressure carbon dioxide to remove objectionable free fatty acids from rice bran oil. The current study increases the efficiency of the high pressure refining process by applying a thermal gradient along the fractionation column and consequently improving the purity of the final and by-products of the process.

Technical Abstract: Crude rice bran oil (RBO) may contain high levels of free fatty acids (FFA) due to the presence of an active lipase in the bran. Conventional refining processes remove a significant portion of the RBO components with nutraceutical value. A supercritical fluid fractionation (SFE) technique has been proposed as an alternative process for vegetable oil deacidification. However, effect of a temperature gradient application along the SFF column on the composition of RBO fractions has not been reported to date. The objective of this study was to compare the effect of isothermal or temperature gradient SFF tower operation on the efficiency crude RBO deacidification. The effect of CO2 flow rate and fractionation time on the extract and raffinate compositions was also examined. A temperature gradient operation of the column was more effective in removing the FFA and reducing the triglyceride (TG) losses during the deacidification process. FFA acid content of the extract increased and TG content decreased with respect to time during extended fractionation runs. Increasing the CO2 flow rate from 1.2 L/min to 2 L/min did not affect the extract composition significantly.