Extraction Of Oryzanol From Rice Bran Miscella

Oryzanol in rice bran oil can be used in food, medicine, cosmetics and other fields. In this paper, a new enrichment process of oryzanol in rice bran miscella was systematically studied, and its anti-oxidation ability was tested.Extraction method in this paper is as follows: rice bran oil blended with hexane refined twice, oryzanol trapped into the soapstock of the second alkali refining; the soapstock dissolved in methanol prior to filtration; then the solution precipitated by citric acid and vaccum filtrated to give crude oryzanol. Final products is obtained by further purification.Through single factor experiment, the optimal refining process was established:1) the first alkali refining: acid value reduction 6, NaOH concentration 5%(w/v), oil to hexane ratio 1:2, reaction temperature 55℃, reaction time 60min, under this condition, the loss rate of oryzanol is only 3.6%; 2) the second alkali refining: NaOH concentration 11%(w/v), reaction temperature 55℃, reaction time 60min, after treating under the best condition, the trapping rate of oryzanol can reach 84.9% and oil refining yield is 90.8%. The optimum preparation conditions optimized by RSM were as follows: NaOH concentration 10.64%(w/v), reaction temperature 59.19℃, reaction time 106.7min. Under these conditions, the trapping rate of oryzanol was 86.60%.After the second alkali, the quality of the rice bran oil was evaluated. The retention of oryzanol in the oil was 8.13%, acidity value 0.3(KOH)(mg/g) and colour Y33R3.0, which has reached Grade 3 requirement of rice bran oil.The soapstock dissolved in methanol was subjected to filtration followed by precipitation using citric acid. Through single factor experiment, the optimal conditions were determined as follows: Acid precipitation pH 6, citric acid concentration 20%, acid precipitation temperature 60℃, acid precipitation time 30min and crystal growing temperature 20℃.Orthogonal experiments were performed to determine the optimal condition: citric acid concentration 20%, acid precipitation temperature 65℃, acid precipitation time 30 min. Under this condition, oryzanol yield was 64.6%, purity was 99.6%. Oryzanol obtained were characterized with HPLC and IR spectroscopy.Two methods, i.e. heating in vaccum under stirring and heating in normal pressure under stirring,were adopted to remove solvent. The former gives samples no-detectable of solvent. While when heating temperature was 70℃, strring for 5 min in the other method, the solvent residual can be reduced to industrially acceptable level.