Identification and quantification of cholesterol oxides in grated cheese and bleached butteroil

Butteroil samples bleached with benzoyl peroxide (BP) and 17 commercial cheeses were screened for oxidized sterols by thin layer chromatography (TLC). Ungrated cheeses made from bleached milk and freshly bleached butteroil contained no detectable oxidized sterols. Oxidized sterols were detected in stored, bleached butteroils and in grated cheeses. Four major oxidation products were the isomeric 5,6-epoxycholesterols and the epimeric 7-hydroxycholesterols identified by TLC, high performance liquid chromatography (HPLC) and mass spectrometry (MS). Additional sterol oxides (tentatively identified and not quantified) present in these samples included low levels of 7-ketocholesterol and cholesta-3,5-dien-7-one. The epimeric 7-hydroxycholesterols were detected in bleached butteroils stored in air (BP-A) and nitrogen (BP-N) for 22 days at 15 C. Butteroil, after 90 days of storage at 15 C, had 30 (BP-N) and 60 (BP-A) μg total oxides/g of bleached oil and, after 1-year at −20 C, had 70 (BP-N) and 180 (BP-A) μg/g butteroil. A grated, unbleached cheese packaged in clear glass contained the most oxidized sterols (44 μg/g). Sterol oxides were not detected in bleached cream using a simulated industrial process.     

Chemical studies on corn embryos infected by various fungi

The occurrence of various fungi in corn kernels obtained from eight localities in Egypt in two successive years was studied. Values for refractive index, color, acid value, saponification value, iodine value, peroxide value and unsaponifiable matter content of oils extracted from corn embryos that were deliberately infected by various fungi were compared to those for oil extracted from healthy embryos. Spectrometric analyses (UV, visible and IR) were done to deduce differences in the functional groups of the oils. Corn oil extracted from embryos infected with various fungi contained the same lipid classes as the oil extracted from healthy embryos. Contents of mono- and diglycerides and free fatty acids were much smaller for the oil extracted from healthy embryos. The fatty acid and unsaponifiable compositions of oils were studied by gas liquid chromatography. The fatty acid composition of corn oil extracted from infected embryos showed that some new and short-chain fatty acids had appeared and that some of the 18:2 was converted to 18:0. Analysis of the hydrocarbon fraction of the unsaponifiables showed also that some new compounds had appeared and others disappeared. The sterols were greatly influenced by the fungi and the ratio between different sterols might be used to characterize the effect of fungi. Aflatoxin B₁ content of oil extracted from corn embryos infected byA. flavus was 300 μg/kg.     

Optimization of formic acid hydrolysis of corn cob in xylose production

Dilute acid pretreatment of lignocellulosic material is one of the significant steps in a biorefinery. We used response surface methodology to determine the important factors of formic acid concentration (2%–6% wt%), treatment time (30–150 min), reaction temperature (120–160 °C), and liquid to solid ratio (3–11 mL/g) on dilute acid hydrolysis of corn cob to produce xylose. A xylose yield of 81.6% and selectivity of 15.1 g/g were achieved under the optimal conditions (5% acid concentration, 150 min, 135 °C, and 7 mL/g liquid to solid ratio). The addition of trivalent salts (FeCl₃, Fe(NO₃)3, and Fe₂(SO₄)₃) to the reaction system enhanced the xylose yield but decreased selectivity. The FeCl₃ concentration over 0.75 mol/L had a negative effect on xylose production.     

Detection of cocoa butter equivalents in chocolate

The fatty acids at the sn-2 position and the sterol composition of cocoa butter and three common cocoa butter equivalents (CBE), namely Coberine, Choclin and Calvetta, were studied comparatively, in order to develop a sensitive method for detecting CBE in chocolate. Differences observed in the composition of saturated fatty acids at position-sn-2 present some interest in detecting CBE in chocolate. Differences found in 4-desmethyl and 4-methylsterol compositions, although quite significant, did not present any practical interest because of the relatively small amounts present in CBE. The 4,4′-dimethylsterol or triterpene alcohol fraction was found to have a potential for determining CBE in chocolate. Thus, the triterpene alcohols of Coberine were further fractionated on argentation thin layer chromatography (TLC) and analyzed by gas liquid chromatography (GLC) and gas chromatography-mass spectrometry (GC-MS). α-Amyrin was found in 48.2% of the triterpene alcohols of Coberine and was absent from cocoa butter. Cycloartenol, the main 4,4′-dimethylsterol of cocoa butter, and α-amyrin were well resolved on an OV-17 glass capillary column.     

Antioxidative effects of polyamines

The antioxidative effects of spermine, spermidine and putrescine were determined by measurement of primary and secondary oxidation products of polyunsaturated fatty acids, using gas and liquid chromatography as well as spectrophotometric recordings. It was demonstrated that polyamines inhibit the oxidation of polyunsaturated fatty acids,α-tocopherol and carotenoid pigments. Both linear and nonlinear dose/response relationships have been observed. The efficiency of a given polyamine was correlated with the number of amine groups in the molecule. Spermine was, thus, more efficient than spermidine, which in turn had a higher efficiency than putrescine. The relative antioxidative effect was as follows: spermine (100.0), spermidine (61.0), putrescine (23.0), ethoxyquin (27.6), ascorbyl palmitate (18.3), octyl gallate (7.9), tert butylhydroquinone (6.3), butylated hydroxyanisole (3.6) andα-tocopherol (3.4).     

Sterols and Stanols in Foods and Dietary Supplements Containing Added Phytosterols: A Collaborative Study

An international, multilaboratory collaborative study was carried out to evaluate the performance of Official Method Ce 12‐16 of the American Oil Chemists’ Society (AOCS) for the determination of plant sterols and stanols, collectively referred to as phytosterols, in foods and dietary supplements containing added phytosterols and in the phytosterol food additive concentrates used to prepare such products. AOCS Official Method Ce 12‐16 involves the extraction of free sterols/stanols and saponified steryl/stanol esters followed by the gas chromatographic separation and flame ionization detection of phytosterol trimethylsilyl ether derivatives. A total of 14 laboratories from six countries successfully completed the analysis of collaborative samples of foods (e.g., baked goods, beverages, margarines; n = 9), dietary supplements (n = 5), and phytosterol concentrates (n = 4). Study results for the contents of total phytosterols (weight/weight) were 0.19–8.4% for foods, 8.7–49% for dietary supplements, and 57–97% for concentrates. AOCS Official Method Ce 12‐16 showed acceptable performance for total and individual phytosterols, indicating that this method was suitable for the determination of added phytosterols in a wide variety of market products and concentrates. AOCS Official Method Ce 12‐16 is appropriate for the determination of the five major phytosterols (i.e., campesterol, stigmasterol, β‐sitosterol, campestanol, and sitostanol) that are the subject of the United States Food and Drug Administration's health claim for phytosterols and the reduced risk of coronary heart disease.     

The antioxidant activity of amino acids in two vegetable oils

Of 27 amino acids studied, most had some antioxidant activity when added in aqueous solution to either safflower oil or a mixture of sunflower and cottonseed oil (active oxygen and storage methods). Cysteine-HCl, glutamic acid-HCl (in the mixture), and glutamic acid-HCl (in safflower oil) behaved as prooxidants. When added as a solid, most amino acids were ineffective. The protection factors of these amino acids were less than 1.3 in safflower oil with methionine, proline, lysine and cysteine providing the highest activ-ity. In the oil mixture (which had a higher metal content) lysine, arginine, glutamic acid, methionine, and hydroxyproline were anti-oxidant with protection factors of up to 1.85. Chelation of metals by amino acids was presumably responsible for the antioxidant activity. The increase in cysteine concentration up to 1% has more than doubled the protection factor in Bint oil (compared with the 0.01% level), whereas with some other amino acids the increase was either small or slight.     

Analysis of triacylglycerols in leaves of citrus by HPLC

Lipids were extracted from leaves of cold-hardened and unhardened citrus plants and the crude triacylglycerol (TG) fraction of each sample was separated from other lipid components by silica gel column and thin layer chromatography (TLC). To determine TG levels and molecular species, the crude TG was subjected to High presure liquid chromatography (HPLC), 12 fractions collected and these fractions quantified by gas liquid chromatography (GLC). Levels of TG/g fresh leaf were 139 μg in unhardened sour orange, 2460 μg in cold-hardened sour orange and 672 μg in cold-hardened Valencia orange. Twenty-one molecular species were determined in the 36–46 equivalent carbon number range (ECN). Five of the TG species that contained linoleate accounted for over 60% of total TG in hardened sour orange and Valencia leaves. Hardened sour orange leaves contained 2–5 times more of these major TG species than hardened Valencia leaves. The increase in these TG species may relate to cold tolerance since sour orange seedlings are more cold hardy than Valencia budded on sour orange. Presented at the 73rd Annual Meeting of the AOCS, Toronto, May 1982. Southern Region, Agricultural Research Service, U.S. Department of Agriculture.     

Physicochemical characterization of galactosyldiglycerides and their quantitation in wheat flour lipids by high performance liquid chromatography

A high performance liquid chromatographic (HPLC) method was developed for analyzing digalactosyldiglycerides (DGDG) and monogalactosyldiglyceride (MGDG) in polar lipids fractionated from lipid extracts of wheat or flour. Wheat lipid samples were prepared by solvent extraction, then fractionated on a silica gel packed open column. A Spherisorb ODS (octadecyl silane) column with methanol/water elution system was used for separation of glycolipids in the polar lipid fractions. The detection limit of the refractive index detector with interferometric optics was 0.25μg for both DGDG and MGDG. Separating on nonpolar bonded phase columns permitted us to differentiate, based on fatty acid composition and position, among components within the specific glycolipid classes. Semipreparative HPLC on analytical columns was used to subfractionate the polar lipids. The glycolipids were collected for functional group characterization. Approximately 35% of each DGDG subfraction was accounted for as carbohydrate. The absence of phosphorus precluded phospholipids. Fatty acid analysis by gas chromatography showed the first DGDG to be linoleic acid, whereas the second DGDG peak was composed of linoleic, oleic and palmitic acids. Mass spectrometric analysis of the first DGDG peak showed linoleic acid in both the SN-1 and 2 positions. Mass spectrometric analysis revealed that palmitic or oleic acid in the second peak was preferentially located on the SN-1 position; linoleic acid was on the SN-2 position. Contribution no. 80-207J, Department of Grain Science and Industry, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS. Part of a dissertation submitted by T.N. Tweeten in partial fulfillment of the PhD degree. Honored Student Award Presentation at AOCS annual meeting, San Francisco, April 1979.     

Preparation and characterization of a new polymer/pharmaceutical-based composite. Part I: Meloxicam

Composites of low-density polyethylene (LDPE), poly(ethylene-co-vinyl acetate) (EVA), poly(ethylene-co-octadecene), and an LDPE/EVA blend were prepared with different amounts of meloxicam (1, 3 and 5 wt %) by the melt blending process. Meloxicam was homogenously dispersed in polymer matrices. The polymer–meloxicam composites showed thermal behavior and thermal characteristics similar to those of the original polymers. Meloxicam release from the composites was examined in vitro for 50 days. The composites were incubated in phosphate-buffered solution and meloxicam concentration was determined by high-performance liquid chromatography. The prolonged release of the drug indicates that meloxicam-loaded plastic rings offer potential for control of reproduction and chronic inflammatory conditions.     

Sterols,methyl sterols,triterpene alcohols and fatty acids of the kernel fat of different malagasy mango(Mangifera indica) varieties

The kernel fat content of 16 different mango varieties collected from the Northwestern part of Madagascar island were examined. The fat content (22–54%) was determined by chloroform/methanol extraction. Investigation by gas liquid chromatography (GLC) revealed 15 fatty acids, mainly palmitic (7–12%), stearic (22–40%), oleic (41–48%) and linoleic (7–17%). Significant correlations were observed among the main fatty acids. Testing for the sterol fraction in 15 mango varieties allowed us to separate and quantitatively analyze 7 sterols by GLC. The main sterols wereβ-sitosterol (47–76%), stigmasterol (12–23%) and campesterol (7–12%). The stigmasterol/campesterol ratio (1.2:2.3) was lower in mango kernel fat than in cocoa butter. Among the 4-methyl sterol fractions, gramisterol, lophenol, obtusifoliol and citrostadienol were tentatively identified by GLC. Lupeol, cycloartenol,α- andβ-amyrins and friedelinol were tentatively identified by GLC in the triterpene alcohols fractions.     

Lipids in chinese medicine. Characterization of allcis 5,11,14,17-eicosatetraenoic acid inBiota orientalis seed oil and a study of oxo/furanoid esters derived fromBiota oil

The fatty acid composition ofBiota orientalis seed oil consists of palmitic (5.1%), stearic (3.4%), oleic (15.3%), linoleic (25.6%), linolenic (34.7%), C20:3(11c,14c,17c) 4.9%, and C20:4(5c,11c,14c,17c) 10.5%. The unsaturated fatty esters derived fromBiota oil were epoxidized and subsequently treated with NaI-PrI-DMSO. Chromatographic separation of the complex product mixture revealed the presence of C18-oxo, C18-furanoid, and C18-and C20-oxo-furanoid esters. Epoxidation of a pure sample of C20:4(5c,11c,14c,17c) followed by NaI-PrI-DMSO treatment gave a mixture of C20-dioxo-furanoid esters. The positions of the oxo and furanoid groups in the various derivatives were determined by GC/MS analysis.     

Occurrence of conjugated fatty acids in the seed oil ofcouepia longipendula (chrysobalanaceae)

The seeds ofCouepia longipendula contain 74.2% oil. Gas chromatography (GC) and gas chromatography/ mass spectrometry (GC/MS) of the methyl esters and oxazoline derivatives of the fatty acids and ultraviolet (UV), infrared (IR),¹H-nuclear magnetic resonance (NMR) and¹³C-NMR spectra of the oil showed the presence of palmitic (25.2%), palmitoleic (0.9%), stearic (6.2%), oleic (26.5%), vaccenic (0.4%), linoleic (7.4%), arachidic (0.3%), α-eleostearic (11.3%) and α-licanic (21.8%) acids. Licanic acid methyl ester was isolated by thin-layer chromatography (TLC) and the¹³C-NMR and¹H-NMR data are presented.     

Determination of Fecal Sterols Following a Diet with and without Plant Sterols

The aim of this study was to develop a method for neutral fecal sterols determination in subjects receiving a normal diet with or without a plant sterols-enriched beverage using gas chromatography–mass spectrometry (GC/MS). Sample preparation conditions (homogenization of lyophilized feces with water) were evaluated. Sterol determination required direct hot saponification, unsaponifiable extraction with hexane, and the formation of trimethylsilyl (TMS) ether derivatives. The method allows the quantification of cholesterol, plant sterols and their metabolites (coprostanol, coprostanone, cholestanol, cholestanone, methylcoprostanol, methylcoprostanone, ethylcoprostenol, stigmastenol, ethylcoprostanol and ethylcoprostanone). Good linearity was obtained (r > 0.96) and interference was only observed for coprostanone, where the standard addition method proved necessary for quantification. The limits of detection (LOD) ranged from 0.10 to 3.88 µg/g dry feces and the limits of quantitation (LOQ) from 0.34 to 12.94 µg/g dry feces. Intra- and inter-assay precision (RSD %) were 0.9–9.2 and 2.1–11.3, respectively. Accuracy, expressed as percentage recovery (80–119%) was obtained for all determined sterols.     

Lipid,sterol and fatty acid composition of antarctic krill (Euphausia superba Dana)

The lipid classes, fatty acids of total and individual lipids and sterols of Antarctic krill (Euphausia superba Dana) from two areas of the Antarctic Ocean were analyzed by thin layer chromatography (TLC), gas liquid chromatography (GLC) and gas liquid chromatography/mass spectrometry (GLC/MS). Basic differences in the lipid composition of krill from the Scotia Sea (caught in Dec. 1977) and krill from the Gerlache Strait (caught in Mar. 1981) were not observed. The main lipid classes found were: phosphatidylcholine (PC) (33–36%), phosphatidylethanolamine (PE) (5–6%), triacylglycerol (TG) (33–40%), free fatty acids (FFA) (8–16%) and sterols (1.4–1.7%). Wax esters and sterol esters were present only in traces. More than 50 fatty acids could be identified using GLC/MS, the major ones being 14∶0, 16∶0, 16∶1(n−7), 18∶1(n−9), 18∶1(n−7), 20∶5(n−3) and 22∶6(n−3). Phytanic acid was found in a concentration of 3% of total fatty acids. Short, medium-chain and hydroxy fatty acids (C≤10) were not detectable. The sterol fraction consisted of cholesterol, desmosterol and 22-dehydrocholesterol.     

Characterisation of Moringa stenopetala seed oil variety “Marigat” from island Kokwa

The oil from Moringa stenopetala seeds variety Marigat from the island Kokwa was extracted using 3 different procedures including cold press (CP), extraction with n‐hexane and extraction with a mixture of chloroform:methanol (1:1) (CM). The yield of oil was 35.7% (CP) to 44.9% (CM). The density, refractive index, colour, smoke point, viscosity, acidity, saponification value, iodine value, fatty acid methyl esters, sterols, tocopherols (by high‐performance liquid chromatography), peroxide value, Eequation/tex2gif-stack-1.gif at 232 nm and the susceptibility to oxidation measured by the Rancimat method were determined. The oil was found to contain high levels of unsaturated fatty acids, especially oleic (up to 76.40%). The dominant saturated acids were behenic (up to 6.01%) and palmitic (up to 6.21%). The oil was also found to contain high levels of β‐sitosterol (up to 52.19%%of total sterols), stigmasterol (up to 16.53% of total sterols) and campesterol (up to 14.26% of total sterols). α‐, β‐ and δ‐tocopherols were detected up to levels of 98.00, 44.50 and 82.41 mg/kg of oil, respectively. The reduction of the induction period (at 120 °C) of M. stenopetala seed oil ranged from 29.4% to 54.7% after degumming. The M. stenopetala seed oil showed high stability to oxidative rancidity. The results of all the above determinations were compared with those of a commercial virgin olive oil and Moringa oleifera seed oil.     

Comparison of Supercritical Fluid and Hexane Extraction Methods in Extracting Kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis>) Seed Oil Lipids

The objective of this study was to investigate and compare fatty acids, tocopherols and sterols of kenaf seed oil extracted by supercritical carbon dioxide and traditional solvent methods. Fatty acids, tocopherols and sterols were determined in the extracted oils as functions of the pressure (400 bar, 600 bar), temperature (40 °C, 80 °C) and CO₂ flow rate (25 g/min) using a 1-L extraction vessel. Gas chromatography was used to characterize fatty acids and sterols of the obtained oils while tocopherols were quantified by HPLC. No differences were found in the fatty acid compositions of the various oil extracts and the main components were found to be linoleic (38%), oleic (35%), palmitic (20%) and stearic acid (3%). Extraction of tocopherols using high pressure (600 bar/40 °C, 600 bar/80 °C) gave higher total tocopherols (88.20 and 85.57 mg/100 g oil, respectively) when compared with hexane extraction which gave yield of 62.38 mg/100 g oil. Extraction of kenaf seed oil using supercritical fluid extraction at high temperature (80 °C) gave higher amounts of sterols when compared with hexane extraction.     

Chemical Composition of Seed Oils Recovered from Different Pear (Pyrus communis L.) Cultivars

Lipophilic bioactive compounds in oils recovered from the seeds of eight pear (Pyrus communis L.) cultivars were studied. Oil yield in pear seeds ranged between 16.3 and 31.5 % (w/w) dw. The main fatty acids were palmitic acid (6.13–8.52 %), oleic acid (27.39–38.17 %) and linoleic acid (50.73–63.78 %), all three representing 96–99 % of the total detected fatty acids. The range of total tocochromanols was between 120.5 and 216.1 mg/100 g of oil. Independent of the cultivar, the γ‐tocopherol was the main tocochromanol and constituted approximately 88 %. The contents of the carotenoids and squalene were between 0.69–2.99 and 25.5–40.8 mg/100 g of oil, respectively. The β‐sitosterol constituted 83.4–87.6 % of total sterols contents, which ranged between 276.4 and 600.1 mg/100 g of oil. Three significant correlations were found between oil yield and total contents of sterols (r = ?0.893), tocochromanols (r = ?0.955) and carotenoids (r = ?0.685) in pear seed oils.     

Waxes and volatile oils inHypericum ericoides (Guttiferae)

A wax isolated from an hexane extract ofHypericum ericoides L. was shown to contain only an, aldehydic and an alcoholic fraction. The aldehydic fraction was found to be largelyn-octacosanal (≈77%), with minor amounts of other linear homologous aldehydes, whereas the alcoholic fraction was almost puren-octacosanol. From the same hexane extract, a volatile oil was also isolated and studied by combined gas chromatography-mass spectrometry (GC-MS). Monoterpene, sesquiterpene and aliphatic straight chain (C₈–C₁₁) hydrocarbons, sesquiterpene alcohols and aliphatic long-chain acids (C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₄, C₁₆ and C₁₈) were found. Biogenetic relationships are discussed.     

Systematic protocol for the accumulation of fatty acid data from multiple tissue samples: Tissue handling,lipid extraction and class separation,and capillary gas chromatographic analysis

A systematic procedure was developed for detailed fatty acid profiling of both neutral and polar lipid fractions isolated from hundreds of related bovine muscle and adipose tissue samples. A regimen was established for a nonbiased handling of tissue samples, which included their handling in a predetermined random order. Lipid class separation was accomplished concomitantly during the extraction of the tissues by a selective dry column method, which allowed a detailed analysis of minor but important polyunsaturated fatty acids associated with the polar fraction. Neutral lipids were derivatized to fatty acid methyl esters (FAME) by a literature procedure. However, to protect against lysis of plasmalogens in the polar fraction, a modified nonacidic esterification procedure was developed. FAME profiles were obtained on a program-mable high resolution capillary gas chromatograph (GC). Run programs for unattended GC operation and data storage are described. By this overall procedure, the quantitation and peak identification were obtained for major and minor fatty acid constituents from bovine tissue in a manner that prepares for valid statistical interpretation of the resulting data.