| Rice bran is the by-product of rice processing. Our country is one biggest rice production country in the world, according to statistics, annually, China's has 13?14 million tons of rice bran for rice processing. Lick the soybean, the composition of 15% ?23% of rice bran are oil, As a important natural source of vegetable oil,rice bran oil is rich in unsaturated fatty acid also has mush oryzanol,sterol, vitamin E, squalene, etc.which functional to enhance immunity, reduce cholesterol, blood fat, prevent arteriosclerosis, or other active ingredients. Most studies in the world also research to improve the effect of extracting, rather than to enhance the oryzanol content of rice bran oil. It made the rice bran oil rancidity deterioration while the fat adipose decompose after the lipase contains of the rice bran good contact with the oil under the mechanical action of rice processing. It has many technical difficulties in the traditional rice bran oil refining process for oryzanol, sterol was taken with the nigre in refining processing. This thesis research in the local rice quality Longjing 46 rice bran as raw material, explores the influence of different solvents to extraction yield of rice bran oil, the content of ?-oryzanol and ?-sitositosterol. As follows:1.Each component testing of Longjing 46 rice bran. Refer to the national standard method of rice bran in crude protein, crude fat, ash content, moisture content, total fiber, carbohydrates are analyzed in test. The results of concluded that the fat content of 17.03%, it's one of best oil fuel in varieties rice bran.2. More y-oryzanol and ?-sitosterol element of extraction processing.sterol extraction of rice bran oil. This thesis explored the influence by n-hexane, ethyl alcohol, isopropyl alcohol, acetone, cyclohexane, pentane for extraction yield, the content of y-oryzanol and ?-sitosterol. The results of concluded that an optimal experimental group for extraction yield is n-hexane (71.34%), the highest content of P-sitosterol is isopropyl alcohol group (0.35%), the highest content of y-oryzanol is anhydrous ethanol group (1.78%). Therefore, we do the next step experiments on the above three kinds of solvents.3. The ratio and selection.of mixed solvent:each two solvents mixed the volume ratio at 9:1,7:3,5:5,3:7,1:9, and explored the influence to extraction yield of rice bran oil, the content of y-oryzanol and ?-sitosterol.Through the statistical analysis software IBM SPSS statistics 19.0 deal with principal component and the contribution value analysis, it is concluded that the best solvent is the mixed solvents isopropyl alcohol with n-hexane by volume ratio at 3:7 (withdrawal rate:72.49%, y-oryzanol:72.49%, P-sitosterol:0.61%).4. Base from single factors of rice bran oil extraction experiments by the mixed solvents above, Under three extraction parameters with extraction time, liquid/solid ratio, and extraction temperature, were optimised by response surface methodology. The results shows 3 sets process parameters. Balance weight of the 3 sets of parameters weight that the optimal process conditions for liquid/solid ratio, temperature and extraction time were 6.81,40.29?,3.5 h, Theoretical value: extraction rate:87.71% and ?-oryzanol:1.56%, p-sitosterol:0.54%.Under the optimum condition, the experimental oil yield was 87.83±0.12%, content of ?-oryzanol wasl.56%, content of ?-sitosterol was0.54%, they are all close to the predicted value.5. Researches for degumming process of rice bran oil. The results by Orthogonal test show the best degumming process parameters for acid was 0.15%, water was 5.0%,temperature was 65?, time was 40 min.Under the condition of the rice bran oil degumming rate was 91.13%, the y-oryzanol, loss rate was 12.22%, ?-sitosterol loss rate of 6.99%. After degumming phosphorus content is 22.07 mg/Kg.6. Studied to enzymatic esterification-alkali refining deacidification process of rice bran oil. Firstly made the FFA esterification with the glycerin under impact on fat enzyme,then add alkali to rice bran oil continue to deacidify. The results of optimum process parameters of glycerol amount was 125.58%, enzyme amount was 8.375%, the temperature was 66.63?, time was 9.62h. After validated experiment, it is concluded that acid value is 6.86 ±0.02%, close to optimize the predicted value of 6.82, and y-oryzanol, loss rate of 0.61%±0.04%, p-sitosterol loss rate of 0.43%± 0.02%, all within the normal range. The reliable model of deacidification was effective.Alkali refining acid process parameters as follows:The results shows 3 sets process parameters. Balance weight of the 3 sets of parameters weight that the optimal process conditions for alkali concentration was 22.07°e, alkali refining temperature was77.94?, time was 27.41 min, prediction results:acid value was 1.29, y-oryzanol reduction was10.06%,?-sitosterol reduction was 8.38%.According to the above response surface optimization condition, three sets of parallel tests is:the acid value was 1.28±0.01%, y-oryzanol reduction was10.30%±0.05%, ?-sitosterol reduction was 8.23%±0.04%, optimization predictive value close to that model of degumming effect is reliable.7. Enzymatic esterification-alkali refining deacidification process was compared with the direct alkali refining process.Concluded show that acid yield of enzymatic esterification-alkali refining deacidification process was reduced 14.45% than direct alkali refining process; The y-oryzanol reduction was reduced 47.69% than the late deacidification process; And the ?-sitosterol reduction was reduced 36.67% than the late deacidification process; Composition of fatty acids is 81.3% which more than 4.5% to the late deacidification process. The content of TAG and DAG in the oil of enzymatic esterification-alkali refining deacidification process were 5.98% and 1.03% higher than the oil of direct alkali refining process respectively.Instructions proved enzymatic esterification-alkali refining deacidification process has more advantages. |
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