Deacidification From Rice Bran Oil By Molecular Distillation And The Research Of Fatty Acid Separation

Rice bran oil is a vegetable oil made by rice bran that a byproduct from riceprocessing, rich in nutrients and the ratio of fatty acid is fit for body to absorb, so itwas recognized as the nutrition and health care oil in the world. The activity oflipase in rice bran was quite high, causing the acid value of rice bran oil was quitehigh, so deacidification was the most important step in the process of rice branoil refining. The traditional methods used for the deacidification of rice bran oilneeded high energy consumption and the loss of nutrients was serious. Moleculardistillation technology was an emerging technology on oil deacidification, and ithad the advantage of low energy consumption, little destruction to the oil, clean, etc.So molecular distillation technique was used for the deacidification test of rice branoil, and the effect of degumming was examined at the same time. The contentof vitamin E (VE) and sterol were tested before and after the deacidification of ricebran oil to examine their extent of losses. Finally the urea inclusion testwas conducted to separate and concentrate the unsaturated fatty acids from freefatty acid. The main conclusions were as follows：(1)The deacidification test of rice bran oil was conducted by moleculardistillation technique. Based on the single-factor test, the Box-Behnken responsesurface experiment was carried on. The optimum conditions of deacidification bymolecular distillation were as following：temperature208℃, speed183r/min,feedrate2.05mL/min. Under this condition the acid value was1.00mgKOH/g, theperoxide value was2.53mmol/kg, the validated test was done and gained the acidvalue was1.01mgKOH/g, the peroxide value was2.52mmol/kg, and the relativeerror were both less than1%. The acid value was three national standard of ricebran oil, as the peroxide value was one national standard. Thus moleculardistillation technology was effective on deacidification of rice bran oil. Thephospholipid content was detected and there were no significant change before andafter deacidification, indicating that the deacidification conditions did not havesignificant removal effect on the phospholipids.(2) The major nutrients in rice bran oil vitamin E and sterol content were tested before and after deacidification, high efficiency liquidchromatography(HPLC) method was used for the measured of vitamin E content,and gas chromatography(GC) for sterol content. The results were that： the VEcontent before and after deacidification had no significant changes, proving thatmolecular distillation technology had very little destruction to VE in rice bran oil,but the sterol content had a significant change before and after deacidification. Themolecular distillation temperature was the most important factor, while the speedand feed rate had no significant influence. This instructed that sterol was moresensitive to temperature, especially when the temperature reached200℃,the ste-rol lost more than90%.(3)Urea inclusion test was studied to the mixed free fatty acids from the ricebran oil, in order to separate and concentrate the unsaturated fatty acids.Orthogonal experimental design was carried out based on the single-factor test, andthe optimum inclusion conditions were： the ratio of fatty acid to urea was1：1.5,the ratio of urea to95%ethanol was1：7, the inclusion time was16h, the inclusiontemperature was-10℃. Then the unsaturated fatty acid content was96.2%. Themost influential factor for the test was the ratio of fatty acids to urea, and thesmallest was the inclusion time. The unsaturated fatty acids that separated wasmainly oleic and linoleic acids, and the ratio was about1：1.