The Research On Bioactive Components Of Rice Bran Oil Deodorizer Distillate

The object of this study is rice bran oil deodorizer distillate. We investigated the relationship between refining process and bioactive components in deodorizer distillate, explored the characteristics of deodorizer distillate, and provide the foundation of the science of further utilization. The simultaneously analytical method of crude sterol and phytosterol was developed in our study. We also founded the techniques about extraction and isolation of sterol and tocopherol, which were based on the physical deacidification and enzymatic esterification. Furthermore, we established the refining process of sterol, and evaluated function of rice bran sterol regulating the blood fat in rats.In the study of refining process, we discussed the characteristics of rice bran oil deodorizer distillate effected by degumming, deacidification, bleach, dewaxing, and deodorization technology. Our results proved that the water content, acidity and peroxide value decreased from1.12%,8.25%and8.54meq/kg to0.05%,0.09%and0.26meq/kg in refining process, respectively. At the same time, the contents of unsaponifiable matter, fatty acid and tocopherol were rarely changed in the refining process.We analyzed the components and physicochemical characteristics of deodorizer distillate. The water content and acidity were0.8%,49.35%respectively. Moreover, the content of unsaponifiables, crude sterol, tocopherol was23.03%,14.82%and1.42%respectively, which proved that the rice bran oil deodorizer distillate was important source for isolation of sterol and tocopherol. It is necessary to remove fatty acid, and control the water content in pretreatment process when we extracted the bioactive components in deodorizer distillate. Our data proved that the fatty acids were similar with them in rice bran oil. The ratio of palmitic acid, oleic acid and linoleic acid in deodorizer distillate was20.32%,41.29%, and31.78%respectively. In the storage of rice bran oil deodorizer distillate, the package should be filled with inert gas, because that the content of unsaturated fatty acid was75.26%easily initiating oxidation reaction.We established the colorimetric analytical method detecting sterol in the deodorizer distillate, which was a rapid and convenient determination with recovery rate as91-103%, and relative standard deviation less as5%. The color reaction was15minutes, and determinated wavelength was630nm. With above analytical methods, we detected the content of crude sterol in the deodorizer distillate of rice bran oil, rapeseed oil, soybean oil and corn oil. Moreover, we also found the analytical method based on gas chromatography for plant sterol. The sample was firstly dissolved with petroleum ether, then made it for silanization, finally analyzed with flame ionization detector. The detailed chromatography parameters were helium carrier gas flow rate as0.5ml/min, detector temperature as320℃, FID air flow rate as280ml/min, FID hydrogen flow rate as30ml/min, and FID supplemental nitrogen flow rate as-20ml/min.We established the extraction and isolation technology of sterol and tocopherol, which were based on the physical deacidification, enzyme catalyzed esterification, tryglyceride ester transesterification, cooling crystallization, molecular distillation. The pretreatment technology was temperature as105℃, vacuum degree as100Pa. The water content decreased from0.8%to0.05%after thin-film evaporation. Meanwhile, we analyzed the recovery rate of tocopherol and acid value of molecular distillation by single factor and orthogonal experiments. The important index decided the efficiency of molecular distillation was in proper sequence as distillation pressure, vapourizing temperature, scraped film speed and feed rate. The optimum technological conditions determined by extreme difference analysis were feed rate as11ml/min, vapourizing temperature as145℃, distillation pressure as13Pa, and scraped film speed as300rpm/min, recovery rate of tocopherol as82.52%, free fatty acid as76.01%. Moreover, we founded the technological process of enzyme catalyzed esterification by single factor experiment, which include enzyme dose as0.0010g/g, temperature as60℃, reaction time as4h, and recovery rate as95%. Furthermore, we studied the conditions of glyceride transesterification, such as solvent ratio as lOg/min, temperature as70℃, transesterification time as2h. The content of glyceride decreased from18.65to0.58%. We also found the conditions of cooling crystallization, comparing with natural cooling process, cooling with refrigerator and cultured crystallization temperature, and obtained the crude sterol with purity as50%.We explored the four phase distillation process. The first and second distillation were same as feed rate as11ml/min, vapourizing temperature as105℃, distillation pressure as 13Pa, and scraped film speed as300rpm/min. The third distillation was feed rate as11ml/min, vapourizing temperature as195℃, distillation pressure as13Pa, and scraped film speed as300rpm/min. The fourth distillation was feed rate as11ml/min, vapourizing temperature as135℃, distillation pressure as13Pa, and scraped film speed as300rpm/min. The purity of tocopherol was52.35%, and recovery rate was78.45%after fourth-molecular distillation process. At last, we analyzed purity and recovery rate of sterol effected by the cooling rate, solvent ration and cultured crystallization time. With the response surface optimization experiment, the purity and recovery rate of sterol was92.25%and86.68%, when the optimal conditions were such as cooling rate1.54℃/min, solvent ration10(ml/g) and cultured crystallization time9.40h. Our product was similar with commercial sterol at appearance, purity, melting point, optical rotation and other physical characteristics.We explored the important role of rice bran sterol in preventing and curing the hyperlipemia in rats. The total serum cholesterol, low density lipoprotein, triglyceride and atherogenic index except for high density lipoprotein were obviously decreased in rats administered with our rice bran sterol. We also found that the live weight and liver coefficient of rats decreased with hyperlipidemia rat model fed with rice bran sterol. When compared the results of RBS55low dose group, RBS55high dose group and RBS90group, we found the sterol with purity of90%was more efficient in modulating hyperlipemia than the RBS55low dose group and RBS55high dose group.