Extraction Of Vitamin E And Phytosterol From Rapeseed Oil Deodorizer Distillate And Synthesis Of Conjugated Linoleic Acid Sterol Ester

As the by-product of refining process, rapeseed oil deodorizer distillate (RODD) mainlycontains free fatty acid, glyceride, vitamin E and phytosterol, is the ideal material forproducing biodiesel, extracting vitamin E and phytosterol. However, there are a series ofproblems such as low biodiesel yield, high loss rate of vitamin E, huge organic solventconsumption and long crystallization procedure in the present technology. Besides,phytosterol could not be widely applied due to its low solubility in both water and oil. Inthis paper, compound lipases were employed to catalyze RODD for biodiesel production,esterification product was crystallizated and filtered after reaction. The filtrate was usedfor separating biodiesel and vitamin E, and the filtered cake was used for refiningphytosterol. Then, the high purity phytosterol was further synthesized into conjugatedlinoleic acid sterol ester (CLS) catalyzed by Candida rugosa lipase so as to enlarge itsapplication. The main research contents and results are summarized as follows:1. Biodiesel prepared from RODD using compound lipases (Novozyme435andimmobilized PS) as catalyst. Single factor experiments and orthogonal experiments wereemployed to inverstigate the effects of different operational parameters on biodiesel yieldand vitamin E loss rate. The optimized reaction conditionswere: compound lipases dosage2.5%(w/w, oil weight), compound lipases rate1:1(w/w), oil/methnol rate1:0.25(m/v),reaction temperature35℃，reaction time8h. Under this condition, biodiesel yield ofcompound lipases reached97.63%,17%higher than that of single lipase. Besides, theretention rate of vitamine E was up to98.19%, vitamin E loss rate was18%less than thatof using chemical catalyst.2. Purification of phytosterols by ultrasonic crystallization method. Single factorexperiments and orthogonal experiments were used to examine the influence of differentoperational parameters on phytosterol yield and purity. The obtained optimal operationconditions were: ultrasonic power75W, ultrasonic time1.5min, crystallization time2h,the rate of material/solvent1:10(m/v). Under these conditions, phytosterol yield attained85.7%, phytosterol purity was up to96.2%. Compared with traditional menthod, organicsolvent consumption reduced50%, and crystallization procedure was shortened2/3~7/8. 3. Synthesis of CLS with C. rugosa lipase. CLS was synthesized in n-hexane systemcatalyzed by C. rugosa lipase. Based on single factor experiment, the reaction conditionswere further optimized by response surface method using the degree of esterification asthe evaluation index. The optimal conditions were: acid-sterol mole ration6:1, reactiontemperature40℃, catalyst loading9.6%(w/w, substrate weight)and reaction time87h.Under the optimal conditions, the degree of esterification between sterol and conjugatedlinoleic acid reached97.5%. In addition, the esterification product was indetified as CLSby thin-layer chromatography (TLC) and Fourier Transform Infrared Spectroscopy (FTIR)analysis.4. Extraction of vitamin E by molecular distillation method. Esterified product(removed phytosterol) was used as the first molecular distillation material to removebiodiesel. Single factor experiments showed that the optimal distillation temperature was100℃, scraping speed was150r/min, and feed rate was90mL/h. Under the condition,vitamin E was concentrated from4.9%to29.5%, and the retention rate was up to98.7%.Distillation residue was conducted a second distillation to extract vitamin E. Theoptimized conditions from single factor experiments were: distillation temperature160℃,scraping speed170r/min, feed rate80mL/h. Under this condition, the purity of vitamin Ewas up to83.4%, and the recovery rate was94.6%. Compared with reported technologies,the extraction process was simplified, and purity and yield of vitamine E were evenhigher.