Analysis Of Oil-soluble Components Of Lotus Plumule And The Extraction And Purification Of Sterol Esters

Lotus plumule contains a large amount of sterol esters, which are considered to be effective in reducing serum cholesterol concentrations, and preventing cardiovascular and cerebrovascular diseases. The analysis, extraction and purification of sterol esters from lotus plumule were investigated in this study, and the natural highly purified sterol ester was obtained. The oil-soluble components of lotus plumule were analyzed by TLC and GC, etc. methods. The extraction of sterol esters was using solvent extraction method, the purification of sterol esters was using column chromatography, and the properties and compositions of sterol esters product were analyzed in this work.A combination method of TLC and GC-MS/FID was established to analyse the total sterols, free sterols and sterol esters of Hunan, Jiangxi and Fujian lotus plumule oil. Results showed that, the content of total sterols of lotus plumule oil was 10.93-12.76 g/100 g, the content of free sterols was 0.86-1.06 g/100 g, the content of sterol esters was 17.86-20.04 g/100 g. Sitosterol(45.16 %-54.67 %) and △5-avenasterol(25.74 %-33.10 %) were predominant sterols of esterified sterols; the linoleic acid(63.56 %-65.87 %), oleic acid(8.32 %-10.35 %) and behenic acid(9.04 %-9.92 %) were the main fatty acids of sterol esters. The main components of lotus plumule oil were glycerides, followed by sterol esters, free sterols, diacylglycerols, monoglyceride, free fatty acids, phospholipids, chlorophylls, and carotenoids.The sterol ester was extracted by organic solvent. The n-hexane, diethyl ether, alcohol, methanol, acetic ether and acetone were used as extraction solvents; acetone was selected by the comparison of sterol ester yield. The extraction process was optimized by response surface based on the single-factor experiment. Results showed that, The extraction yield was 85.09±1.04 % under the condition of temperature was 45℃,time was 12 min, solid-liquid ratio was 1:12 g/mL, extract 3 times. The extraction process was simple and convenient, short time, less energy consumption, high extraction yield, single solvent easy to recovery and utilization.The sterol ester of crude product was purified by the column chromatography. The crude product contained much glycerides, fatty acids and pigments, etc. Column chromatography technology was used to solve the challenging problem that the separation between sterol esters and other components. The type of adsorbent, elution solvent, loading amount, elution flow rate and column height to diameter ratio as independent variables, and purity and recovery of sterol esters as dependent variables, The purification process of sterol esters were optimized as: silica gel(200-300 mesh), elution solvent was petroleum ether: diethyl ether: acetic acid(v/v/v=90:10:1), elution flow rate was 1.0 mL/min, loading amount was 2.0 g,column height to diameter ratio was 12:1(chromatographic column height, 36 cm; silica gel, about 80g), the purity and recovery of sterol esters was 95.56% ±1.32 % and 95.70±3.05 %, respectively. The purification process could obtain high purity sterol esters from lotus plumule extracts directly, and the purified product was a pale yellow oily liquid, which was a kind of natural sterol esters.