Study On The New Technology For Preparation Of High Value-added Products From Rapeseed Oil Deodorizer Distillate

Rapeseed oil deodorizer distillates(RODDs)are rich in fatty acids,glycerides,vitamin E,phytosterol and other useful substances.However,due to the limitation of deep process technology,they are used mainly as livestock feed with a very low products’ additional value nowadays,resulting in serious resource waste.Therefore,in this paper,RODDs were used as feedstock and their useful components were separated and processed to obtain high value-added products.Firstly,glycerides and fatty acids were converted into biodiesel with the catalysis of liquid synergetic lipases.After that,sterols were recovered by cooling and filtrating the esterification products.It was then reacted with conjugated linoleic acid(CLA)to prepare conjugated linoleic acid sterol esters(CLS),which can be easily absorbed by human body.Finally,biodiesel and vitamin E were extracted and purified via molecular distillate.The main work and results of the thesis were summarized below.1.Methyl esterification were carried out respectively to prepare biodiesel by low cost liquid Candida rugosa lipase(CRL)and Rhizopus oryzae lipase(ROL)fermented by our laboratory.Through single factor optimization,a final 92.6% of biodiesel yield catalyzed by CRL was obtained under the optimized conditions of lipase concentration 750 U/g,water content 50 wt%(w/w),temperature 35°C,and reaction time 30 h.While for ROL,it could obtain 94.4% of biodiesel yield under the optimized conditions of lipase concentration 200 U/g,water content 37.5wt%(w/w),temperature 40°C and reaction time 9 h,which showed obvious advantage over CRL not only in biodiesel yield but also in reaction speed.2.The synergetic effect between liquid CRL and ROL was investigated and applied to promote the methyl esterification of RODDs to convert into biodiesel.Single factorial experiments and response surface methodology(RSM)optimization were further employed to optimize the reaction conditions.The finally optimal conditions were ROL ratio(ROL/total lipase amount)0.84,water content 46 wt%(w/w),reaction temperature 34°C,and under the optimal conditions,the highest biodiesel yield could attain 98.2% within 6 h,which showed higher biodiesel yield and shorter reaction time than both single lipases.Moreover,the retention rate of vitamin E could reach 97.1%.3.CLS was prepared through esterification between phytosterol and CLA with the catalysis of protein-coated microcrystal(PCMC)CRL.Through optimization,the esterification rate could reach 97.5% under the optimal conditions of molecular sieves addition 74 mg/mL,hexane 10 mL,molar ratio of CLA to phtosterol 6:1,the amount of microcrystal enzymes 38%,reaction temperature 40°C,reaction duration 48 h.It has not only improved the esterification rate but also shortened the reaction duration when compared with free enzyme.4.Molecular distillation was utilized to extract and purify biodiesel and vitamin E.Through first distillation stage,biodiesel was recovered with a content of 98.0% and a recovery rate of 92.1% under the optimized conditions of distillation temperature 100°C,feed rate 50 mL/h,membrane scraper rotating rate 180 r/min.Vitamin E was then enriched through optimizing parameters of the second distillation stage,where the heavy phase of the first distillation was used as the distillation material.Under the optimal conditions of distillation temperature 160°C,feed rate 70 mL/h,membrane scraper rotating rate 160 r/min,the obtained recovery rate of vitamin E could reach 92.3%,and its content was 61.4% which was 10.6 times higher than that of the original oil.