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Steryl esters extraction

Fig. 4 LC-GC-FID chromatograms for typical olive oils. The nearly complete absence of wax esters (esters 40-esters 46) and very low concentrations of steryl esters indicate a high-quality extra virgin oil. The concentration of free stigmasterol is low. C24-26-OH, fatty alcohols. In lampante oils, more wax esters and steryl esters are found. The concentration of stigmasterol increases more than campesterol if the oil was prepared from olives of low quality. Run at the same sensitivity, chromatograms of solvent-extracted oils are completely overloaded. The refined extraction oil was diluted 1 5 before running the chromatogram shown. Wax ester and steryl ester concentrations are very high. (From Ref. 34, p. 626.)... Fig. 4 LC-GC-FID chromatograms for typical olive oils. The nearly complete absence of wax esters (esters 40-esters 46) and very low concentrations of steryl esters indicate a high-quality extra virgin oil. The concentration of free stigmasterol is low. C24-26-OH, fatty alcohols. In lampante oils, more wax esters and steryl esters are found. The concentration of stigmasterol increases more than campesterol if the oil was prepared from olives of low quality. Run at the same sensitivity, chromatograms of solvent-extracted oils are completely overloaded. The refined extraction oil was diluted 1 5 before running the chromatogram shown. Wax ester and steryl ester concentrations are very high. (From Ref. 34, p. 626.)...
Standard methods of analysis of total sterol content of oils involve saponification of the oil, followed by extraction and isolation of total sterols from the unsaponihable fraction by thin layer chromatography (TLC) (AOCS, 1998). Quantification of individual sterols involves silylation of the sterol fraction and analysis by gas chromatography (GC). Sterols and steryl esters in oils and fats can be analysed by LC-GC after silylation or acylation of the free sterols (Artho et al., 1993). An alternative approach to the analysis of intact steryl esters involves separation of sterols and steryl esters by solid phase... [Pg.147]

The preparation of high-purity tocopherols and phytosterols involves steps such as molecular distillation, adduct formation, liquid-liquid extraction, supercritical fluid extraction, saponification, and chromatography (175). The extraction of tocopherols from soybean oil deodorizer distillate by urea inclusion and saponification of free fatty acids resulted in good recovery of tocopherols (208). To improve the separation of sterols and tocopherols, Shimada et al. (209) used a lipase to esterify sterols with free fatty acids. Then the steryl esters and tocopherols were separated better by molecular distillation. Chang et al. (210) used supercritical fluid CO2 extraction to recover tocopherols and sterols from soybean oil deodorizer distillate. A patent by Sumner et al. (211) advocated treatment of the distillate with methanol to converted free fatty acids and other fatty acid esters to methyl esters that can then be removed by a stripping operation. Then separation of sterols and tocopherols could be carried out by molecular distillation. [Pg.1249]

To determine sterols, a portion of the total lipid extract is saponified using methanolic potassium hydroxide, and sterols subsequently recovered in 2 1 hex-ane/chloroform. The sterols are converted to the corresponding trimethylsilyl (TMS) ethers using bis-N,0-(trimethylsilyl)trifluoroacetamide, BSTFA, and analyzed by capillary GC and GC with mass spectrometry. Reviews of relative retention times and mass spectra for sterol TMS ethers have been published [e.g. 73]. In some cases, sterol acetates, rather than TMS ethers, are the derivatives prepared for GC. SiHca column chromatography of the total lipid extract may also be used instead of saponification to isolate the sterol fraction [74], or even sterol subclasses such as 4,4-dimethyl, 4-monomethyl and 4-desmethyl sterols [75], prior to derivatization. However, this approach only includes free sterols in the analysis, whereas by saponifying the total extract, sterols present as steryl esters are also detected. [Pg.203]

Procedure 1—10 mg lipid (or a sample of silica gel on which this amount is adsorbed) and 1—2 ml of a 5% solution of dry hydrogen chloride in absolute methanol, are sealed under nitrogen in an ampoule. This is heated on the water bath at 80° C for 2 h (for glycerides) or 4—6 h (with steryl esters and sphingolipids). After cooling, the ampoule is cautiously opened and 5 ml water added to the reaction mixture. The lipids are then extracted 3 times with 10 ml portions of hexane (the reaction products of alkoxylipids are extracted with diethyl ether). The combined extracts are washed twice with 10 ml N potassium carbonate solution and water and dried over anhydrous sodium sulphate. [Pg.372]

Extractives are compounds with low molecular weight which include, amongst others, lipids, phenolic compounds, terpenoids, fatty acids, resin acids, steryl esters, sterol. [Pg.522]

Yeast auxotrophic strain RD5R was grown to stationary phase on 1 yg/ml of C-cholesterol. The cells were washed by centrifugation and varing amounts of additional cholesterol were added. Control cultures without additional sterol supplementation were collected and analyzed. Lipids were extracted, separated, and quantitated as previously described The open symbols represent free cholesterol and the closed symbols represent steryl ester. The circles represent samples that were obtained from cells given different amounts of cholesterol (0.25, 0.5, 1.0, 1.5, 2.0, 3.0, and 6.0yg/ml) and collected after an equivalent amount of time. Squares represent data obtained from cells collected after different lengths of time (0.75 to 18 hours) after addition of 3.5 Ug/ml cholesterol. [Pg.60]

The analysis of plant steryl esters has typically proceeded by isolation of the steryl ester fraction from a plant lipid extract followed by saponification to yield the sterol and fatty acid moieties. These are then identified and quantified by GC analysis, usually after preparation of the fatty acid methyl esters. However, this method of analysis has the disadvantage that the integrities of the steryl esters are lost. With the often multicomponent mixtures of sterols and fatty acid methyl esters resulting from a typical plant steryl ester mixture... [Pg.95]

Another RP-HPLC procedure was applied for the study of the distribution and stability of steryl chlorin esters in copepod faecal pellets from diatom grazing. Pigments were sonicated for 15 min with acetone at 0°C and the procedure was repeated until the extract became colourless. The organic phase was evaporated and the fraction containing the free alcohols was separated by TLC (silica stationary and dichloromethane mobile phases) and analysed by gas chromatography. RP-HPLC measurements were performed in an ODS... [Pg.300]

Kiosseoglou, V. and Boskou, D. (1990) Separation and fatty acid composition of steryl and wax esters in hexane extracts of sunflower seed, soybeans and tomato seeds. Lebensmittel-Wissenschaft and Technologie, 23 (4), 340-2. [Pg.30]

Ibn steryl ferulate and coumarate esters were extracted from com and rice and were identified using a C g column (A = 325 nm) and an 82/3/2/13 acetonitrile/1-butanol/acetic acid/water mobile phase. Good resolution was obtained and the elution was complete in 35 min. Chromatograms showing the effects of varying water level (1-21%) on peak shape and resolution were shown. Levels from 70 pg to 26mg/g sample were tabulated [1065]. [Pg.388]

Figure 2. Thin layer chromatogram of total lipids extracted from microsomal membranes (lane 1) and cytosolic lipid-protein particles (lane 2) isolated from cotyledon tissue of Phaseolus vulgaris. PC, phosphatidylcholine PE, phosphatidylethanolamine PG, phosphatidylglycerol PI, phsophatylinositol FFA, free fatty acids TAG, triacylglycerol SE/WE, steryl and wax esters. Figure 2. Thin layer chromatogram of total lipids extracted from microsomal membranes (lane 1) and cytosolic lipid-protein particles (lane 2) isolated from cotyledon tissue of Phaseolus vulgaris. PC, phosphatidylcholine PE, phosphatidylethanolamine PG, phosphatidylglycerol PI, phsophatylinositol FFA, free fatty acids TAG, triacylglycerol SE/WE, steryl and wax esters.

See other pages where Steryl esters extraction is mentioned: [Pg.320]    [Pg.38]    [Pg.148]    [Pg.333]    [Pg.1968]    [Pg.17]    [Pg.603]    [Pg.166]    [Pg.1114]    [Pg.193]    [Pg.250]    [Pg.824]    [Pg.250]    [Pg.318]    [Pg.337]    [Pg.410]   
See also in sourсe #XX -- [ Pg.9 , Pg.449 , Pg.450 ]

See also in sourсe #XX -- [ Pg.9 , Pg.449 , Pg.450 ]




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