Bestimmung von Schwermetallen in Ölen,Fetten und Futtermitteln

Determination of Heavy Metal Traces in Oils, Fats and Feeding-Stuffs Atomic absorption spectroscopy has proved to be the best method for the determination of lead, cadmium and mercury in fats, oils and feeding-stuffs, whereas colorimetry is best for the determination of arsenic. For each substrate the most suitable digestion method is described. Recoveries and detection limits of the determination methods are shown.     

Die polarographische Bestimmung von Tocopherolen und Tocopherylchinonen in Ölen und Fetten

Polarographic Determination of Tocopherols and Tocopherylquinones in Oils and Fats A method for the polarographic determination of α-, γ-, and δ-tocopherols and the corresponding tocopherylquinones in oils and fats was worked out. After saponification of the samples and extraction of unsaponifiable matter with ether, the tocopherylquinones originally present in oils and fats are directly determined polarographically. Tocopherols present in the sample are oxidized quantitatively with cerium(IV) sulfate to the corresponding tocopherylquinones and latter are then likewise polarographed. The presence of substances accompanying tocopherols in the unsaponifiable matter does not interfere with the determination of tocopherols or tocopherylquinones. The tocopherol contents of different oils and fats are given.     

Quantitative Bestimmung von polycyclischen aromatischen Kohlenwasserstoffen in Fetten und Ölen

Quantitative Determination of Polycyclic Aromatic Hydrocarbons in Fats and Oils A method, based on liquid-liquid partition and column as well as thin-layer chromatography, for the qualitative and quantitative UV-spectrophotometric determination of 13 polycyclic aromatic hydrocarbons present in fats and oils, is reported. The limit of detection lies between 0.1 to 0.5 μg/kg, the recovery between 55 and 60% and the relative standard deviation between 5 and 20%. A determination in duplicate requires about 3 days. Another procedure, requiring a few hours for the determination of groups of the polycyclic aromatic hydrocarbons in 20 g fat or oil, which provides only semi-quantitative results, is reported as well.     

Schnellmethode zur quantitativen Bestimmung individueller Tocopherole in Ölen und Fetten

A Rapid Method for the Quantitative Determination of Individual Tocopherols in Oils and Fats Oils and fats were two times frozen from acetone solution at ?80°C under protection by ascorbyl palmitate. Tocopherols (T) and tocotrienols (T₃) present in the filtered extract are separated into their homologues by one-dimensional TLC on pre-coated silica gel plates, the extract having been streaked and developed three times in the n-hexane/ethyl acetate system 92.5:7.5. Complete separation of the positional isomers β-T and γ-T is accomplished as well whereas β-T₃ and γ-T are assumed to form identical bands. Suitable spray- and detection systems including new found coloring ones are described for the qualitative estimation of the chromatograms. Values are given for the content of individual tocopherols T/T₃ of 24 commercial plant oils (bands measured by Emmerie-Engel procedure).     

Polarographische Bestimmung von Hydroperoxiden in Ölen

Polarographic Determination of Hydroperoxides in Oils The application of direct current polarography for the determination of hydroperoxides in oils has the following advantages over other methods: 1) specific for the hydroperoxides, 2) independent of the structure of hydroperoxides, 3) even very small amounts (upto 10^?6 mol/1) are detectable and 4) relatively short time is required. In comparison to chemical determination the accuracy of the polarographic determination is ± 3% and in case of very small hydroperoxide content (<10^?5 mol/1), it is ± 10%.     

Bestimmung des Xanthophyllgehaltes von Pflanzenölen

Determination of Xanthophyll Content of Vegetable Oils The DGF official method F — II 2 enables the separation of carotenoid hydrocarbons from the unsaponifiables using a Al₂O₃ column. This method can be extended by the successive use of polar solvents. Thus, polar carotenoids can also be separated. Spectrum of each fraction from the Al₂O₃ column is obtained and the fractions are further separated in a MgO-celite column. Identification of individual carotenoids is done on the basis of absorption spectra as well as the nature and number of polar groups determined by thin-layer chromatography on silica gel plates. Content and composition of carotenoids in several vegetable oils, such as soybean, sesame, sunflower, corn germ and low-erucic rapeseed oil were determined by this technique. All these oils contain mainly dihydroxy carotenoids.     

Quantitative Bestimmung der apolaren dimeren Fettsäuren in Fetten und Ölen

Quantitative Determination of Unpolar Dimeric Fatty Acids in Fats and Oils Fatty acids obtained by saponification of fats followed by removal of unsaponifiables and petroleum ether insoluble oxidized fatty acids, were treated to give urea-adducts. The mixture of fatty acids which did not form adducts was esterified and separated by thin-layer chromatography. It was shown by mass-spectrometry that the methyl esters of unpolar dimeric fatty acids occupied a definite zone in the chromatogram. The methyl esters of unpolar dimeric fatty acids can be quantitatively estimated by charring the chromatogram under standardized conditions and densitometry of the above zone, whereby a test substance is co-chromatographed for comparison. The relative standard deviation in the chromatography and densitometric determination was approximately 10%. The lower limit of detection was at 0.005% of the methyl ester of unpolar dimeric fatty acid. Using dimeric fatty acids lebelled with radioactive carbon, it was proved that approximately up to 90% of the unpolar dimeric fatty acids can be detected by this method.     

Vergleich einiger Methoden zur Bestimmung des Oxiran-Sauerstoffgehalts von Ölen und Fetten

Comparison of a Few Methods for the Determination of Oxirane Oxygen Content of Oils and Fats The accuracy and reproducibility of four methods were compared by multiple determinations of oxirane oxygen contents of 9,10-epoxystearic acid, alone or in conjunction with varnish grade linseed oil, of epoxidized oil, as well as of heat treated oxidized oil. Besides the direct method employing HBr/glacial acetic acid three indirect procedures were tested. The differences amongst the above methods lie in titrating agents and end point indication. Especially with regard to attainable accuracy the method employed by the author involving potentiometric end point indication is distinctly advantageous as compared to coloured indicators. None of the methods tested is applicable for the determination of oxirane oxygen content at a level < 0.01%.     

Zur Bestimmung,zum Vorkommen und zur Zusammensetzung von polycyclischen aromatischen Kohlenwasserstoffen in Ölen und Fetten

On the Occurrence, Determination and Composition of Polycyclic Aromatic Hydrocarbons in Crude Oils and Fats Various methods have been published regarding analytical determination of polycyclic aromatic hydrocarbons (PAH). In principle, all methods are composed of following steps: Enrichment, clean-up and quantitation. The authors prefer the caffein-complexation technique. They have been using this since many years for the routine PAH-analysis of fats and oils. This report contains the results of PAH determination in the most common crude oils used in Europe as well as the statistical trend of their contamination with “light” and “heavy” PAH's. Moreover, the PAH contamination of different oils according to their geographical origin is shown and possible sources of contamination are discussed. The role of Benzo[a]pyrene as the “reference PAH” and its correlation with “heavy” PAH is subjected to a critical evaluation.     

Untersuchung und Beurteilung von PAK in Speisefetten und -ölen

Investigation and Legal Evaluation of Polycyclic Aromatic Hydrocarbons in Vegetable Fats and Oils The analysis of 40 native and refined commercially available vegetable fats and oils reveals the influence of the environment and the treatment on the contamination with PAHs. Totally refined oils and fats have no or only a low contamination of PAHs whereas grapeseed oil contains PAHs to a high extent. This fact has to be deduced to the old-fashioned drying process of the pressed grapes. The analytical procedure with HPLC and fluorimetric detection was done after alcaline hydrolysis. The PAHs were extracted using the distribution between DMF, cyclohexane and water. The legal evaluation of high contaminated is discussed in regard of national and international regulations.     

Eine Schnellmethode zur Bestimmung von Lösungsmittelresten in extrahierten Ölen

A Rapid Method for the Determination of Residual Solvents in Extracted Oils The content of petroleum solvents and trichloroethylene can be determined in extracted vegetable oils within 15 minutes, upto a limit of 0.01%, at an accuracy which is adequate for the practice. Air is blown through the sample of oil at room temperature and the escaping air current containing the solvent is passed through Dräger indicator tubes, such as hydrocarbon tube KW 2, or trichloroethylene tube 10/a. Length of the discoloured zone is directly proportional to solvent content of the oil.     

Sterin- und Fettsäurezusammensetzung in Keimölen

Sterol and Fatty Add Composition in Germ Oil The sterol and fatty acid composition of 10 various wheat samples and one maize sample were investigated as well in the germ as in the endosperm to determine characteristics for identity and purity controls. A constantly low content of stigmasterol and an extremely high total sterol content are criteria for pure wheat germ oil. Another characteristic is the presence of small amounts of 5-dihydrositosterol and 5-dihydrocampesterol from lipids of the endosperm in germ oils obtained by technology.     

Zur Darstellung und Charakterisierung von Vinylsenfölen

Synthesis and Characterisation of Vinylisothiocyanates The preparation of vinylisothiocyanates by treatment of γ-chloroallylchlorides with KSCN followed by rearrangement of the γ-chloroallylthiocyanates is described. The structure is proved by the reaction of the vinylisothiocyanates with mercaptides and by spectroscopic methods.     

Experimentelle Bestimmung von molekularen und effektiven Diffusionskoeffizienten am Beispiel der gasunterstützten Abpressung von Speiseölen

The solvent‐free production of edible oils from oilseeds is steadily gathering more importance. Therefore, gas‐assisted pressing is an innovative process. Knowlegde of the diffusion kinetics of the gas is essential in order to optimize the process. In this paper experimentally obtained molecular diffusion coefficients of CO₂ in pure rapeseed oil as well as effective diffusion coefficients of CO₂ within the oil of oil‐bearing rapeseed presscake are presented. The acquired diffusion coefficients are compared to literature correlations and adjustments are presented. Comparison of molecular and effective diffusion coefficients resulted in an diffusion resistance factor of the surrounding solid of 2.1.     

Filtration von Speiseölen und Fetten und deren Automatisierung

Filtration of Edible Oils and Fats and Its Automation The various filtration operations in the edible oil industry are given. Processes are listed in which pressure filters, consisting of a pressure vessel and filter elements provided with metal cloth are advantageous. Automation of various filtration operations using these filters is finally dealt with.     

Vitamin E und Haltbarkeit von Pflanzenölen

Vitamin E and stability of vegetable oils. The main occurrence of vitamin E basing on its synthesis and its lipophilic character are vegetable oils, seeds, nuts and cereals. The most important task of tocopherols are their antioxidative capacity in food lipids. The antioxidative potential of tocotrienols in comparison to their corresponding tocopherols is lower. According to the chemical structure γ- and δ-tocopherol are more effective than α-tocopherol. An improvement of the antioxidative capacity is possible by controlled adding to tocopherol compounds as well as by the use of synergists like ascorbylpalmitate. For this improvement the composition of fatty acids, the tocopherol content in native oil and the circumstances of the oxidation should always be considered.     

Neue Tocopherol-Bestimmungs-Methoden und deren Anwendung bei Pflanzenölen

New Methods for the Tocopherol Determination and Their Application in Vegetable Oils The author checked the methods for the determination of tocopherols in oils and carried out series of experiments to work out modified or new methods which enable the separation of tocopherols and their rapid determination without decomposition. He used the thin-layer chromatography for the separation and developed with the help of the data available in the literature two modified methods for the determination of total tocopherols and the homologous components side by side. In the course of further experiments he eliminated the saponification step which is characteristic for the usual methods and worked out direct methods of determination.     

Die kontinuierliche Hydrierung von Ölen und Fetten

Continuous Hydrogenation of Oils and Fats The processes described till now for the continuous hydrogenation of glycerides are reviewed. The various systems are classified from the viewpoint of the reactor involved and their advantages and disadvantages are discussed. As an example of a modern plant for continuous hydrogenation, the reactor of BUSS AG, Basel, is described in details and its operational characteristics in the selective hydrogenation of fish oil are reported. The effect of pressure, temperature and catalyst concentration on the dilatation properties of the products at various temperatures and iodine values is given. Pressure was found to be the most important factor governing the selectivity. Finally, the consumption figures of a 150 to and a 250 to per day plant are presented.