The Studies On Enzymatic Lipolysis Of Rice Bran To Prepare Diacylglycerol Oil And The Effect Of Refining Technology

Fresh rice bran as raw material, its oil was hydrolysised into diacylglycerol byendogenous lipase during it was storaged under different conditions was invested，and highacid value of rice bran oil as raw material, the influence of refining technology on thecontent of diacylogycerol in rice bran oil was invested.The main research is about the rice bran hydrolysis rate and characteristics affected bythe content of moisture, storage temperature, pH value and Ca²⁺. The hydrolysis propertiesof rice bran were reflected by the rate of changement in acid value of rice bran oil and thecontent of diacylglycerol. And then analysised the relationship between acid value and thecontent of diacylglycerol, and discussed the relationship of storage conditions of rice branand the content of diacylglycerol. The results indicated: in the same storage condition ofmoisture content, the order of the hydrolysis rate of rice bran was as follows:45℃>35℃>25℃>5℃; While moisture content was about10%-20%, the hydrolysis rate of highmoisture rice bran was faster; The relationship between the content of diacylglycerol andthe acid value of rice bran oil was as follows: while the acid value was in the30mg/g-40mg/g, the content of diacylglycerol reached the maximum content, among30%-35%. Calcium chloride solution has positive effecting on the activity of lipase in ricebran.In different measuring temperature conditions, the lipase activity was highest at45℃,while at5℃was minimum. Four different pH values （5.0,6.0,7.0,8.0） calcium chloridesolution adjusting the moisture content of rice bran stored at35℃, the higher content ofdiacylglycerol in the condition of pH7.0，is33.3%.High acid value of rice bran oil as raw material, the deacidification and the content ofdiacylglycerol was studied, which was deacided by the immobilized lipase Novozym435and LipozymeRM IM catalyzing esterification of glycerol and rice bran oil. The optimalcondition of dedification Novozym435catalyzed by response surface was: the enzymeconcentration3%of oil weight, the reaction temperature86℃, addition of glycerol additionlevel at222%of the theory, the reaction time6h, acid value declined from24.1mg/g to3.9mg/g. The impact factors affecting content of the diacylglycerol rice bran oil ester inorder was: the addition of glycerol, enzyme dosage, reaction temperature, the highest estercontent was29.76%. Single factor experiments showed that, the best deacidification process of rice bran oil by LipozymeRM IM catalyzed esterification was enzyme concentration4%of the oil, the amount of glycerol addition level of300%of the theory, the temperature70℃,7h, acid value ranged from24.1mg/g down to4.89mg/g, the diacylglycerol contentwas22.70%.Removal of gum, wax and pigment in the crude diacylglycerol rice bran oil by solventand solid was invested. Single factor experiments showed as follows. The best conditions ofsolvent dewaxing: liquid ratio1:2, reaction temperature40℃, reaction time20min. Underthese conditions, the phospholipid content declined from1.67%to0.77%, the acetoneinsoluble content ranged from4.5%to0.9%. Orthogonal test showed that the optimumconditions of solid adsorbent for the decolorization experiments was: adsorbent dosage12%,bleaching temperature100℃, bleaching time20min, the color is from Y70R8.0B8.0（by133.3mm Colorimetric slot） to Y35R1.0（by133.3mm Colorimetric slot）. The result indicatedthat during the refining process of rice bran oil using solvent and solid adsorbent, thecontent of rice bran oil ester in the diacylglycerol was changed slowly.