Chromatographische Methoden bei der Untersuchung von Fritierfetten

Chromatographic Methods in the Investigations of Deep-Frying Fats 125 samples of deep-frying fats were investigated by various chromatographic methods (gaschromatography, gel permeation chromatography, column chromatography). The results were compared with the known criteria of alteration products (petroleum ether oxidised fatty acids (OXF). A content of 0.7% corresponded to 24.7% polar materials. The fraction of monomer glycerides was determined by gel permeation chromatography (GPC) on polystyrol-divinyl-copolymer (PL-Gel) which can be used at high pressure. However, gel permeation chromatography determines the sizes of the molecules and does not distinguish between non-oxidised and oxidised monomer glycerides in frying fats. Therefore the application of gaschromatography and GPC is proposed to calculate the part of non-oxidised monomer tri- and diglycerides. It was found that fat-samples with more than 0.7% oxidised fatty acids contained less than 86.7% monomer non-oxidised and oxidised di- and triglycerides and less than 71.6% monomer unaltered di- and triglycerides.     

Der Futterwert von Fetten und Ölen aus Verarbeitungsprozessen bei Geflügel

Feeding Value of Fats and Oils from Finishing Processes for Poultry Altogether two trials with 22 different fats/oils have been carried out. In the first trial the interesterification and the digestibility of the fatty acids of seven fats and oils from the finishing processes with different contents of polymeres have been determined with broilers, aged 2–3 and 5–6 weeks as well as adult cocks. The age of the animals and the shares of the fatty acids were of high influence on the feeding value. In the second trial the fattening performance of broilers that had got ratios of 13 different frying oils, bleaching earth oils or distillation residues, was determined. The results with frying oils were successful, those with bleaching earth oils were moderate and with distillation residues extremely bad. A dependence between the content of polymeres and the feeding value of fat and oils could not be found out.     

Thermofraktographie – eine neue mikroanalytische Schnellmethode zur Untersuchung von Lipidgemischen

Thermofractography – A Novel Microanalytical Method for the Rapid Analysis of Lipid Mixtures New possibilities now exist for the rapid analysis of lipid mixtures in micro-scale through fractionated carrier gas distillation in direct coupling with the thin-layer chromatography (= Thermofractography). To begin with, the behaviour of pure substances in the temperature gradient 50°–450°C was investigated. It was observed that numerous compounds, which are otherwise separable only via vacuum distillation, pass over with the carrier gas at normal pressure. In this connection, the thermolysis of such compounds was also investigated. Practical cases of application, e. g. fats and oils, mayonnaise, dairy products, chocolate base are given and other possibilities are discussed.     

Fatty acid contents of certain processed foods

Summary Fatty acid constituents of two cheeses, four cured meats, and two hydrogenated oils were determined; two sets of data were obtained for each sample. Unsaturated acids were determined spectrophotometrically in the total fatty acids prepared from each fat, and saturated and unsaturated components were determined chemically and spectrophotometrically on each fraction obtained from distilling the methyl esters prepared from the fats. Close agreement was obtained between the percentages of unsaturated components found in distilled and non-distilled samples. Methyl esters of cheese fats were prepared without prior distillation of steam-volatile acids; no separation of saturated and unsaturated components was made on any sample. Fatty acid components were also converted to percent of each fatty acid in each food. This research was supported in part by the U. S. Department of Agriculture through a contract sponsored by the Bureau of Human Nutrition and Home Economics.     

Aromatenstrukturtypenanalyse von raffinierten Erdölprodukten durch UV-Spektroskopie

Aromatic Structure Type Analysis of Hydrotreated Petroleum Fractions by U.V.-Spectroscopy 20 K boiling cuts were produced from hydrotreated petroleum products by means of distillation. From such close fractions, defined pure aromatic types can be separated by preparative elution adsorption chromatography (EAC) on dual-packed (Silicagel-Alumina gel) columns. The extinction coefficients of the various separated types are measured at suitable wave lengths and used for calculating the average extinction coefficients of aromatic types for wide boiling fractions. Utilizing these values on quantitative u.v.-analysis of technical hydrotreated products, the results correspond well with those of EAC and ¹H-n.m.r. spectroscopy.     

Formation of short‐chain glycerol‐bound oxidation products and oxidised monomeric triacylglycerols during deep‐frying and occurrence in used frying fats

Heating fats and oils at high temperature in the presence of air, a common procedure in culinary practices such as frying, results in a complex mixture of oxidation products. These compounds may impair the nutritional value of the food. Among them, there is a growing interest in the group of oxidised triacylglycerol monomers because of their high absorbability. The main structures in this group include triacylglycerols (TG) containing short‐chain acyl groups formed by homolytic β‐scission of the alkoxy radicals coming from allylic hydroperoxides. In addition there are TG containing oxidised fatty acyl groups of molecular weight similar to that of their parent TG, i.e., epoxy, keto and hydroxy fatty acyl groups. In this review, the main routes of formation of oxidised TG monomers are detailed. Also, the most relevant advances in the analysis of intact TG molecules by high‐performance liquid chromatography coupled with mass spectrometry are discussed. Special attention is paid to the present analytical possibilities for accurate quantification of the most important oxidised compounds formed at high temperature. Both the need to convert fats and oils into simpler derivatives, thus concentrating the compounds bearing the oxidised structure, and the methylation procedure selected to avoid artefact formation are justified. Typical concentrations of short‐chain fatty acids, short‐chain aldehydic acids, short‐chain diacids, and monoepoxy fatty acids, ketoacids and hydroxyacids in frying oils from restaurants and fried‐food outlets, with polar lipids levels at the limit of rejection for human consumption, are given.     

Vergleichende Untersuchung von kommerziellen Fritiermedien

Experimental Comparison of Commercial Deep-Frying Fats. 20 commercial deep-frying fats (consistent and semi fluid) and 2 ‘High Oleic Sunflower Oils’ (HOS-Oils) were investigated for peroxide value, smoke point, fatty acid composition, iodine value, melting point and the relative deep-frying stability (RFS). The RFS was determined by monitoring the increase of the dielectric constant during deep-frying. For not hydrogenated consistent fats (palm fats) the RFS ranged from 9.5 to 12.6 h, for partially hydrogenated consistent fats the RFS was between 14.6 and 19.3 h, for semi fluid fats between 7.4 to 17.4 h, and for HOS-oils the RFS amounted to 15h. The concentration of poly unsaturated fatty acids (PUFA) correlated negatively (r=—0.89; p<0.01) with the RFS of hydrogenated consistent fats. semi fluid fats and HOS-oils. Palm fats showed a different RFS/PUFA ratio. A significant correlation (r=—0.89; p<0.01) was observed between the RFS and the initial polarity of fresh fats.     

Verfahren und Anlagen zur Fraktionierung von synthetischen Fettsäuren

Processes and Plants for the Fractionation of Synthetic Fatty Acids Synthetic fatty acids, prepared by oxidation of paraffins, can be used to save valuable edible fats. Fractional distillation of these fatty acids enable their manifold application. For this, the paraffins have to fulfil certain criteria of quality. In a multiple stage vacuum fractionation process provided with material balance regulator, high boiling complex mixtures can be processed to distillates of high purity. Such a multi-column plant is equipped with stills, fractional columns and rectifying columns, and the plant is controlled by feeding machines. Many years of experience and production data have shown that synthetic fatty acid distillates can be produced economically and these products meet the technical requirements of soap and detergent industry.     

Kolonnenauslegung zur physikalischen Raffination von Ölen - Theorie und Praxis

Column Layout for Physical Refining of Oils - Theory and Practice Because of missing data of phase equilibrium simplifications are often used for the thermodynamic layout of distillative neutralisation of fats and oils. These simplifications do not correctly describe the real behaviour of such systems during distillation. For more than three years trials have been carried out in our pilot plant of physical refining and deodorization. In parallel to these trials computer simulations, using different arrangements for the activity coefficients, have been carried out. The results of the theoretical calculations are compared with the measured data on the basis of some examples.     

Stabilisierung von Kakaobutterersatzfetten

Stabilization of Cocoa Butter Substitute Fats There is an increasing interest in cocoa butter substitute fats, mainly in cocoa butter exchange fats (also called CBE-cocoa butter equivalent). The industry for chocolates and sweets depends on substitute fats of highest quality. The quality estimation of CBE depends on its stability and mixability with cocoa butter (similarities of physical and chemical properties). The stability of cocoa butter substitute fats can be increased to the level of cocoa butter by the ingrediences as tocopherol and lecithine, admitted in the industry for chocolates.     

Unsaturated Fatty Acids as Synergists for Antioxidants

Both the double bond and the carboxyl group are found necessary for the marked synergism exhibited by oleic acid for phenolic antioxidants in vegetable fats. Compounds in which either function is blocked are ineffective as synergists. After considering various possibilities for the mechanism of the reaction, it is proposed that oleic acid hydroperoxides supply hydrogen atoms to the oxidised antioxidant, thus regenerating it.     

Über den Einfluß der Begleitstoffe der Fettsäuren auf die Kinetik ihrer Hydrierung

Ta Influence of Concomitant Substances of Fatty Acids on the Kinetics of their Hydrogenation In the present paper the influence of concomitant substances of animal fats and their degradations components on the kinetics of the hydrogenation of free fatty acids of these fats was investigated. Our attention was directed to the balance of organic sulphur, phosphor and nitrogen compounds during high pressure splitting of fats, distillation of fatty acids and following hydrogenation. During the splitting process 70% of nitrogen and sulphur containing substances were degradated or removed, the content of phosphor containing substances didn't change basically. Another decrease of concomitant substances and their splitting products occurs during distillation of fatty acids. In the subsequent hydrogenation the content of phosphor containing compounds decreased significantly. Residual contents of amino acids and sulphur compounds were absorbed by the Ni-catalyst and contributed to the decrease of its activity. The effect of the confirmed substances on the decrease of its activity. The effect of the concomitant substances on the decrease of the hydrogenation velocity was confirmed by their addition to the fatty acids of sunflower oil after chromatographic isolation. This addition (concentration from 1 to 3%) lowered the reaction velocity up to 50%.     

Preparation of glycerides by controlled esterification

A simple procedure for esterifying glycerides without interesterification occurring would be highly useful for preparing on a large scale a number of tailor-made fats, including cocoa butter-like fats. Such esterifications were carried out by employingp-toluenesulfonic acid as catalyst and continuously removing the water of esterification by azeotropic distillation with aliphatic hydrocarbons or by stripping with vaporized hydrocarbons. Even thoughp-toluenesulfonic acid rapidly disproportionated 1-monostearin, even at 120C, apparently esterification was faster and only a moeerate amoung of ester-ester interchange and acidolysis occurred. Diacid glycerides might be prepared from monoglycerides by the procedure which was employed. Saturated diglycerides were esterified with oleic acid with little ester-ester interchange or acidolysis occurring; however, intraesterification was extensive. The reaction between 1,3-distearin and oleic acid yielded approximately 75% 1-oleodistearin and 25% 2-oleodistearin. Saturated diglycerides were esterified with sebacic acid, again with little or no interesterification occurring. Presented at the AOCS meeting in New Orleans, La., 1962; and at the VIth Congress of the International Society for Fat Research, London, England, 1962. A laboratory of the So. Utiliz. Res. and Dev. Div., ARS, U.S.D.A.     

Über die destillative Entsäuerung von Fetten und Ölen

Distillative Deacidification of Fats and Oils Based on the general principles of steam distillation, a method and diagrams for calculating the consumption of stripping steam in the distillative deacidification of various types of fats and oils are given. With the example of distillative deacidification of palm oil, it is shown as to how the minimum consumption of stripping steam is obtained in a two-step process. Subsequently, the corresponding determinations for palm kernel, coconut, peanut and rapeseed oils are shown. The operational scheme of a continuous plant for distillative deacidification and deodorization as well as photos of the fittings of the distilling cylinder are also included.     

Determination of tocopherol in oxidized fats. Interference from heat-formed reducing substances in highly oxidized fats

Summary and Conclusions By application of a heating method to determine tocopherol in oxidized fats it was shown that polymeric reducing substances were produced when fats have a peroxide value exceeding 100. By comparison with a chromatographic method to remove peroxides it was shown that the interference in determining tocopherol from these heat-produced reducing substances was negligible at peroxide levels lower than 100. It is concluded that the heating method is satisfactory within the peroxide range (0–100) most important in oxidative and flavor-stability studies of edible oils. The chromatographic method for removing peroxides can be relied upon for determining tocopherol in more highly oxidized fats as well as in methyl esters of fatty acids which are distillable under conditions of the heating method. The appearance of reducing substances in heated oxidized fats is related to the peroxides present in the fats prior to heating. It is accompanied with an increase in browning, viscosity, acid, and carbonyl values of the fats and with a decrease in iodine values. The polymeric material from heated-oxidized methyl esters of unsaturated fatty acids has been separated by vacuum distillation and chromatography on silicic acid. It is believed to be principally dimeric in nature.     

Recovery of volatile compounds from butter oil

Three methods for the isolation of volatile compounds from oils and fats were compared using small concentrations (approximately 1 ppm) of added C_3-12 n-alkan-2-ones and C_2-10 n-alkan-1-ols in commercial butter oil. These were : high vacuum degassing, cold-finger molecular distillation and reduced pressure steam distillation. Several modifications were incorporated. The highest yields of all compounds were obtained by cold-finger molecular distillation but difficulties were encountered in subsequent analysis. It was more convenient to recover compounds boiling below 150C by either high vacuum degassing or reduced pressure steam distillation. The latter was more efficient for the higher boiling compounds. Extraction with organic solvents was not required in any of these techniques. The combination of high vacuum degassing and cold-finger molecular distillation was found to be the best method of analyzing the complete range of model compounds.     

Definition von Destillationslinien bei der Trennung von Mehrstoffgemischen

Definition of Distillation Lines in the Separation of Multicomponent Mixtures. In recent years “distillation lines” have been used for the assessment of the separation behaviour of multicomponent mixtures, with these distillation lines being defined differently by different authors. The theory of distillation of multicomponent mixtures shows that it is appropriate to distinguish between residue lines and rectification lines. While the profile of residue lines is determined solely by the thermodynamic phase equilibrium, that of rectification lines also depends upon the mass transfer model used. By analogy with VDI Guideline 2761: “Thermal Separation Processes in Process Engineering”, it is proposed that residue lines and rectification lines are designated by the collective term distillation lines.     

A distillation method for the quantitative determination of malonaldehyde in rancid foods

Summary An improved distillation method is described for the quantitative determination of malonaldehyde in foods containing oxidized fats. The procedure is compared with other methods in current use for the determination of malonaldehyde. A high correlation of TBA numbers with rancid odor in cooked meats was established. This paper reports research undertaken in cooperation with the Quartermaster Food and Container Institute for the Armed Forces, QM Research and Engineering Command, U. S. Army, and has been assigned number 1029 in the series of papers approved for publication. The views or conclusions contained in this report are those of the authors. They are not to be construed as necessarily reflecting the views or indorsement of the Department of Defense. Frank C. Vibrans Senior Scientist Fellow. AMIF, Summer of 1958. Journal Paper No. 182, American Meat Institute Foundation.     

Erfassung und Vermarktung von Schlachttierfetten

Marketing of Animal Fats. A great decrease in the use of animal fats for human nutrition has occurred since many years. Therefore other markets had to be found, which led to large volume of export. Domestic use of animal fats is predominantly for technical purposes. Consequently, no new economical methods were developed for separating high- and low-melting fractions. In the field of animal nutrition, the prejudices are disappearing since several years, and increasing amounts of animal fats are being used. Since animal fats are subjected to the same regulations that govern the treatment of meat, in Germany the refining of animal fats is fundamentally prohibited with few exceptions. In all other countries of European Community refining is permitted. Such discrepancies should be eliminated within the scope of harmonization efforts that are being made in the new food legislation of the European Community.     

Untersuchungen an Fritierfetten; Zusammenhänge zwischen dem Gehalt an petroläther-unlöslichen oxidierten Fettsäuren und dem Gehalt an polaren Substanzen bzw. dem Gehalt an polymeren Triglyceriden

Investigation of Deep-Frying-Fats; Correlations Between the Content of Petroleum Ether-Insoluble Oxidised Fatty Acids and the Content of Polar Substances or the Content of Polymeric Triglycerides Respectively In 1973, the Deutsche Gesellschaft für Fettwissenschaft issued a recommendation of the assessment of used deep-frying fats in which special importance has been attached to the content of petroleum ether-insoluble oxidised fatty acids. However, the determination is time-consuming. Moreover, according to definition, only small amounts of the total oxidised fatty acids are determined. The results of other, less time-consuming methods of investigation which, in addition, may be carried out directly in the deep-frying fat without necessitating chemical attacks have been compared with those of the method ?petroleum ether-insoluble oxidised fatty acids”?. Samples of 4 types of fat which had been used for deep-frying in snack bars under different conditions were investigated by the following procedures:

• 1 Determination of the petroleum ether-insoluble oxidised fatty acids (ox FA)
• 2 Column chromatographic determination (CC) of the polar components
• 3 Liquid chromatographic determination (LC) of the sum of those substances which are more polar than unchanged triglycerides
• 4 Gel permeation chromatographic determination (GPC) of the polymeric triglycerides.

It was found that there are statistical relations between 1. and 2. resp. 3. resp. 4. The mean value of the distributions are laying approximately on parabolas. Thus, it is possible to replace the limit values for the content of petroleum ether-insoluble oxidised fatty acids of 0.7 or 1.0% recommended by DGF by corresponding values of the other methods.