Bestimmung von Tocopherolen in Ölen und Fetten: Einfluß des Tocopherol-Gehaltes von Erdnuß- und Sojaöl auf den Oxydationsverlauf dieser Öle beim Erhitzen I

Determination of Tocopherols in Oils and Fats: Influence of the Tocopherol Content of Ground-nut and Soybean Oils on the Course of Oxidation of these Oils on Heating I A sensitive method for the quantitative determination of α, γ and δ tocopherols in edible oils and fats was worked out. The tocopherols are isolated from unsaponifiable matter by thinlayer chromatography and ultimately each of them was determined photometrically from the red colour formed with iron chloride and bathophenanthroline. The effect of reduction in tocopherol content, resulting from the heating of oils, on the course of the oxidation of oil was followed, among others, with the help of 4-hexylresorcin. The blue dyestuff formed by this reaction was synthesized and identified as trimethin dye.     

Untersuchungen über die Verseifungsfarbzahl

Studies on the Saponification Colour Number Oxidized fats give yellow to brown solutions on saponification with alcoholic potassium hydroxide. Studies reported here were directed towards determining the causes of such reactions. The results indicate that at least two multiple bonds which are conjugated in relation to the carbonyl group, or a α,β-dicarbonyl group give a strong reaction on heating with alcoholic potassium hydroxide. It is shown that under certain conditions of reaction the saponification colour number is suitable as a measure for the degree of oxidation of heated fats. The method employed is described.     

Bestimmung von Sauerstoff und Stickstoff sowie Erfassung primärer Oxydationsprodukte in Ölen,Fetten und Emulsionen auf physikalisch-chemischem Wege I: Methodik

Determination of Oxygen and Nitrogen as well as the Detection of Primary Oxydation Products in Oils, Fats and Emulsions by Physico-chemical Methods A displacement method for the determination of oxygen and nitrogen in oils, fats and emulsions is reported. The method also serves to calibrate the described oxygen determination procedures by Tödt and by Clark. A procedure has been developed with the help of Clark-cell, with which the oxygen content of oils, fats and emulsions can be determined and continuously registered. A polarographic procedure for the determination of fatty hydroperoxides is also described. It is shown with the help of an autoxidation experiment, that the absorbed oxygen is mostly used up in the formation of hydroperoxides.     

Säulen-chromatographische Bewertung der Oxydationsstufe von Fetten und Ölen

Column Chromatographic Estimation of the Extent of Oxidation of Fats and Oils Oxidized fats and oils can be separated into oxidized and unoxidized fractions by column chromatography with aluminium oxide as adsorbent and benzene and ethanol-diethyl ether mixture as eluting solvents. The method is suitable for the evaluation of advanced oxidation where chemical methods can lead to false results.     

Bestimmung der Oxidationsstabilität pflanzlicher Öle über die häminkatalysierte Lipid-Peroxidation

Determination of Oxidation Stability of Vegetable Oils by Hemin Catalyzed Lipid Peroxidation A quick determination method of the relative oxidation stability of sensitive oils and fats is described. The measuring system essentially consists in a reaction cell in which under standardized conditions a hemin catalyzed oxidation of the test material takes place. The oxygen consumption during the reaction is electrochemically measured by means of a Clark-electrode and registrated by a recorder. The test conditions are better controled compared with those of similar, already published methods; therefore the scope of application is extended. Some examples of application are reported and basing on these results a comparison to the Swift test is made.     

Änderung der Preßfähigkeit durch Austausch von Sojabohnen gegen Sojaextraktionsschrot und Öl

Variations in the Pressing Capability by Exchange of Soya Beans for Soya Extraction Meal and Oil Feeding stuff with a high energy content needs the addition of fats and oil. By this, difficulties in pelleting and formation of solid pellets arise. Therefore the subsequent spraying upon the pellets has been applied in industry. This is not the optimum because of possible oxidation and storage difficulties. Therefore the complete soya beans are applied directly, the fat is enclosed in the cells and better protected against oxidation. Trials in this direction confirm this, high fat amounts in the mixture can be pressed to solid pellets, too. The variation of the fat is investigated by samples during pressing. The peroxide values for example show however a detectable increase, but this is by no means of any interest. If the fats are extracted and stored under defined conditions the influence of the pressing procedure is obviously. The oxidation after conditioning and pelleting is different, depending on the meal mixture. High POV occur which indicate a decrease of quality. Also in long term conditioning a distinctly higher peroxide value is obvious. The effect of the pressing process can be observed only during storage under certain conditions. The results indicate that the pressing capability can be considerably influenced by the kind of the fats and by way of addition. On the other hand some questions remain open.     

Studium von UV-Spektren flüchtiger Produkte,die bei der thermischen Oxydation und Autoxydation von Fetten entstehen

Study of the U. V. Spectrums of the Volatile Products Formed by the Thermal Oxidation and Autoxidation of Fats The worked out U. V. spectroscopic distillation method was used for the study of the changes in fat taking place on heating at high temperature and by autoxidation. By a close study of the U. V. spectrums, it was shown that with the help of steam distillation of heated and likewise oxidised fats, saturated and unsaturated aldehydes can be isolated. U. V. spectrums of strongly oxidised fats showed the presence of keto acids and in one case also malondialdehyde.     

Tocopherole — Antioxidative Wirkung bei Fetten und Ölen

Tocopherols — Antioxidative Effect on Oils and Fats The main reason for the deterioration of fats and oils is a chemical reaction between the oxygen and the double bonds which are contained in the unsaturated fatty acids. In the course of the autoxidation intermediate peroxides affect the vitamines sensitive to oxidation. They lower the content of physiologically valuable essential fatty acids. The oxidation stability of oils and fats depends on the natural content of tocopherols as well as on the composition of the fatty acid. The effect of the added tocopherols depends on the natural content of tocopherols. Lipids with lower contents can be stabilized very well with antioxidants consisting of tocopherols. Here animal fats as well as synthetical lipids are considered which in particular are used in cosmetic industry and in the field of pharmacy but also in food industry. Vegetable oils contain, due to their nature, high contents of tocopherols which are partly removed or oxidised during raffination and storage. Therefore adding antioxidants containing tocopherols is adviseable. Also an addition of reducing substances as for instance ascorbylpalmitate is recommended. Moreover antioxidant systems should consist of heavy metal chelating substances.     

Verwendung von Futterfetten in der Tierernährung sowie ihr Einfluß auf die Qualität der Schlachtkörper

Use of Feed Fats for Animal Nutrition and their Influence on the Quality of the Slaughtered Bodies For about 40 years fats have become an important feed component in rations of agricultural working animals. An increase of fat use in compound feed up to forty times was noted in the period from 1955 to 1984. But still today there are signs of uncertainty concerning quality assessment and selection of fats for feeding the various working animals. Today the quality of feed fats can be determined by analysis methods which enable a relatively quick assessment. Unfortunately there is no official control so that at last the compound feed factories have to fulfil this task. As fats have in comparison to carbohydrates an energy value which is 2.3 times higher, the energy amount of the compound feed increases by their addition. Thus the improved genetic ability of putting on weight of the working animals can completely be made use of. A greater fattiness of slaughtered bodies is not caused by fat addition in balanced rations. Because of their variety of different fatty acids and above all by their differences in the consistency and oxidation stability fats are of great influence on the performance of the animals and their slaughtered body quality. Depending on the content of polyenic acids and their oxidation degree lower increases of weight and damages in the organism are possible. High amounts of multiple unsaturated fatty acids cause a worse fat consistency in the slaughtered body and the from that produced products. Furthermore the suitability for storage declines by the lacking stability of the polymeres. Higher additions of vitamin E, Selenium or also of technical antioxidants show positive effects.     

Shelf‐life prediction of edible fats and oils using Rancimat

Determining the shelf‐life of edible fats and oils under normal storage conditions is a tedious and time‐consuming task. Accelerated tests are therefore frequently used to determine the stability of the products at ambient conditions. However, the mechanisms of lipid oxidation at accelerated conditions may be different from those under normal storage conditions, leading to errors in the shelf‐life predictions. This article describes an automated accelerated method, namely Rancimat, for shelf‐life prediction of edible fats and oils under normal storage conditions, and the effect of its operational parameters on these predictions.     

Determination of the glyceride structure of fats

A method has been described for the quantitative determination of the following six glyceride types in fats: SSS, SSU, SUS, SUU, USU, and UUU. The method involved a quantitative oxidation of the unsaturated acids in the whole fat to the corresponding dicarboxylic acids. The oxidized fat was separated on a liquid-liquid partition column into two fractions, the first containing glycerides having no dicarboxylic acid or one dicarboxylic acid and the second containing glycerides with two or three dicarboxylic acids. Analysis of these fractions by gas chromatography coupled with lipase hydrolysis allowed the calculation of the proportions of the above six glyceride types. The oxidation, fractionation, lipase hydrolysis, gas chromatographic analysis, and the over-all method were checked on natural fats and mixtures of synthetic glycerides. The final glyceride composition appeared to be reliable to within plus or minus 2 unit per cent. Analyses are given for five natural fats. The compositions found agree very well with those calculated by a distribution theory recently proposed by Vander Wal. Contribution from the National Research Council of Canada, Prairie Regional laboratory, Saskatoon, Saskatchwan. Issued as N.R.C. No. 6161.     

Die Zusammensetzung ”︁oxidierter Fettsäuren”, ihr Gehalt als Beurteilungsgrundlage für erhitzte Fette und ihre Beziehung zur Verseifungsfarbzahl

Composition of “Oxidized Fatty Acids”, Their Content as a Basis for the Evaluation of Heated Fats and Their Relationship to Saponification Colour Number “Oxidized fatty acids”? obtained from various thermally oxidized fats according to DGF method C-III 3 (68) have been investigated. Empirical formula determined from molecular weight, and C-, H- and O-content, and the possible structural formulas are discussed. During oxidation the content of ?oxidized fatty acids”? increased parallel to the increased in saponification colour number E100%, 1 cm/470 nm. Contrary to other investigations, it has been proved that the relationship between saponification colour number and “oxidized fatty acids? is not affected by the material fried. Thus it is possible to use saponification colour number in combination with acid value as basis for the evaluation of heated fats.     

Effect of induced high linoleic acid and tocopherol content on the oxidative stability of rendered veal fat

Veal calves reared by the Animal Physiology and Genetics Institute, USDA, on milk supplemented with tocopherol then on a diet containing encapsulated safflower oil demonstrated increases in the concentrations of linoleic acid (18:2) and tocopherols in their depot fats. The expected decrease in the induction period of oxidation for these fats with 18:2 levels of 7–12.9% was not observed in the fats with increased tocopherol content. The fat of the treated calves was more stable to oxidation than the fat of commercial veal or pork. ARS, USDA.     

Oxidation stability of biodiesel fuel as prepared by supercritical methanol

A non-catalytic supercritical methanol method is an attractive process to convert various oils/fats efficiently into biodiesel. To evaluate oxidation stability of biodiesel, biodiesel produced by alkali-catalyzed method was exposed to supercritical methanol at several temperatures for 30 min. As a result, it was found that the tocopherol in biodiesel is not stable at a temperature higher than 300 °C. After the supercritical methanol treatment, hydroperoxides were greatly reduced for biodiesel with initially high in peroxide value, while the tocopherol slightly decreased in its content. As a result, the biodiesel prepared by the supercritical methanol method was enhanced for oxidation stability when compared with that prepared by alkali-catalyzed method from waste oil. Therefore, supercritical methanol method is useful especially for oils/fats having higher peroxide values.     

Die Zusammensetzung tierischer Organ- und Depotfette in Abhängigkeit von der Fütterung III: Gas-chromatographische Analyse von Kälberfetten nach definierter Fütterung

The Composition of Animal Organ and Depot Fats in Relation to Feed III: Gas-chromatographic Analysis of Fats from Calves after Definite Feed Within the scope of the feeding experiments, which had been carried out for explaining the accumulation of trans fatty acids in animal organs, we studied the composition of mixed fatty acids of heart, kidney and liver as well as that of the corresponding depot fats with the help of gas-chromatography. The fatty acid composition of the separated neutral fat and phosphatide fractions of the organ fats are discussed.     

A rapid method for the quantification of fatty acids in fats and oils with emphasis on <Emphasis Type="Italic">trans</Emphasis> fatty acids using fourier transform near infrared spectroscopy (FT-NIR)

A rapid method was developed for classifying and quantifying the FA composition of edible oils and fats using Fourier Transform near infrared spectroscopy (FT-NIR). The FT-NIR spectra showed unique fingerprints for saturated FA, cis and trans monounsaturated FA, and all n−6 and n−3 PUFA within TAG to permit qualitative and quantitative comparisons of fats and oils. The quantitative models were based on incorporating accurate GC data of the different fats and oils and FT-NIR spectral information into the calibration model using chemometric analysis. FT-NIR classification models were developed based on chemometric analyses of 55 fats, oils, and fat/oil mixtures that were used in the identification of similar materials. This database was used to prepare three calibration models—one suitable for the analysis of common fats and oils with low levels of trans FA, and the other two for fats and oils with intermediate and high levels of trans FA. The FT-NIR method showed great potential to provide the complete FA composition of unknown fats and oils in minutes. Compared with the official GC method, the FT-NIR method analyzed fats and oils directly in their neat form and required no derivatization of the fats to volatile FAME, followed by time-consuming GC separations and analyses. The FT-NIR method also compared well with the official FTIR method using an attenuated total reflectance (ATR) cell; the latter provided only quantification of specific functional groups, such as the total trans FA content, whereas FT-NIR provided the complete FA profile. The FT-NIR method has the potential to be used for rapid screening and/or monitoring of fat products, trans FA determinations for regulatory labeling purposes, and detection of contaminants. The quantitative FT-NIR results for various edible oils and fats and their mixtures are presented based on the FT-NIR model developed.     

Glyceride composition of fats and oils determined by oxidation and crystallization methods

The glyceride composition of four dissimilar fats and oils was determined by two independent methods a) systematic fractional crystallization from acetone, and b) Kartha’s modification of Hilditch’s acetone permanganate oxidation method. Results by the two methods were in fair agreement for lard, chicken fat, and cottonseed oil but not for palm oil. Calculations were also made of glyceride distribution according to the patterns of random and restricted (Kartha’s hypothesis) distribution. The values calculated for either pattern however did not agree well with those obtained experimentally by either method, except for one of the four fats, chicken fat.     

Über die Kinetik der Autoxidation von Fetten

The Kinetics of the Autoxidation of Fats The kinetics of the inital stages of the autoxidation of fats has been studied by linearization of rate data. All data treated follow the same basic rate equation with a time function f(t) that was empirically derived by Berg for heterogeneous oxidation. Metals and glass (wall of reaction vessel) are catalysts. f(t) expresses the state of the catalyst. The hydroperoxides formed are surface active, they form micelles that can solubilize O₂. Thus the O₂ concentration in the substrate increases with the degree of oxidation and so does the rate of oxidation. Above the upper limit of solubilization the oxidation rate is constant. Added hydroperoxides also increase the oxidation rate in proportion to the amount added.     

A new method for glyceride composition determination by colorimetry

A new method was devised for determination of glyceride composition of fats by oxidation, fractionation of the derived azeleoglycerides by thin layer chromatography and quantitation of the fractions obtained by colorimetry. The method was first standardized with standard triglyceride mixtures and was then applied to wegetable oils and their interesterified mixtures. It appeared to work very well in all cases, including directed interesterified mixtures where the lipase hydrolysis method of glyceride estimation is unsuitable.     

Über Oxysäuren zur Beurteilung erhitzter Fette

Oxy Acids in the Assessment of Thermally Treated Fats The usual characteristic values such as peroxide, aldehyde and epoxide values are mostly insufficient for the assessment of the degree of oxidation of thermally treated fats. Characteristics such as acid value and especially colouration with alkali and oxy acids offer a good insight into the degree of oxidation of a fat. According to the investigations carried out till now a good correlation exists between the alkali colouration and the oxy acids so that the determination of either of the two suffices. The measurement of alkali colouration is preferred, since it is simple and rapid, and permits the simultaneous assessment of oxy acids.