Triacylglycerols (TGs) make up the major part of naturally occurring fats and oils The composition and fine structure of TGs determine to a large extent the functionality of fats and oils as food ingredients and the physiological effects of fats and oils as component of the human diet Analysis of intact TGs is usually performed by chromatographic methods In this article the application of gas-liquid chromatography, high-performance chromatography in normal and reversed phase mode, thin-layer chromatography and supercritical fluid chromatography for the qualitative and quantitative determination of TGs is reviewed Emphasis is put on those factors that are decisive for obtaining reliable quantitative data Furthermore, techniques for the stereospecific analysis of the fatty acid distribution along the glycerol backbone of TGs are presented briefly

Triacylglycerol Profiling by Using Chromatographic Techniques.

Methods for the analysis of triacylglycerols

A method has been developed for the quantitative thin layer chromatographic determination of the triglyceride groups, differing in unsaturation, based on densitometry of the charred bands. Complete separation was achieved by continuous development in an open glass jar. The need for correction coefficients was avoided through addition of bromine to the double bonds prior to charring in the presence of sulphuryl chloride. The accuracy and precision of the method were evaluated on a standard mixture and on sunflower oil, olive oil, lard, cocoa butter, and beef tallow. The method is applicable for triglyceride group analysis of the most common fats and oils which contain saturated, monoene, and diene acids.

Rapid densitometric determination of triglyceride groups by argentation thin layer chromatography

An analytical approach is presented for the study of one-phase interesterification of mixtures of sun-flowerseed oil with fully hydrogenated lard, natural lard, and tallow, based on triglyceride group analysis by argentation thin layer chromatography. The curves for the changes of each of ten triglyceride groups, differing in unsaturation, are reported. These are used to establish the conversion of the initial composition to the random limits in the mixtures cited. The altera-tions in the differential dilatation curves are ex-plained in part by the changes in the triglyceride com-position.

Alterations in glyceride composition during interesterifi-cation of mixtures of sunflower oil with lard and tallow

Triglyceride konnen sowohl mit Hilfe der Umkehrphasen als auch der Silbernitrat-Chromatographie getrennt werden. Bei beiden Methoden treten kritische Partner auf, die durch eine Kombination beider Verfahren weitgehend getrennt werden konnen. Nicht getrennt werden dabei aber isomere Triglyceride. Letztere lassen sich ihrer Struktur nach in verschiedene Klassen aufteilen, wie Stellungsisomere, geometrische Isomere, Isomere mit gleicher Zahl von Doppelbindungen und C-Atomen, aber verschiedenen Fettsauren, sowie Isomere mit stellungsisomeren ungesattigten Fettsauren. Die Schwierigkeiten bei der Trennung dieser Isomeren werden erortert und Beispiele fur die DC-Trennung von Triglyceriden jeder Klasse gezeigt. Die Beispiele an Modellsubstanzen werden erganzt durch die DC-Trennung von Baumwollsaat-, Sonnenblumen-, Oliven-, Erdnus-und Palmkernol.



TLC-Separation of Mixtures of Isomeric and Natural Triglycerides



Triglycerides can be separated by reverse phase as well as by argentation chromatography. In both of these methods critical pairs are formed whose separation can be effected to a large extent by a combination of the two methods. However, isomeric triglycerides can not be separated by the latter procedure. According to their structure, the isomeric triglycerides can be classified into positional isomers, geometric isomers, isomers having the same number of double bonds and C-atoms but containing different fatty acids, and glycerides containing the positional isomers of unsaturated fatty acids. The difficulties involved in the separation of these isomers are pointed out and examples for the TLC-separation of triglycerides of each class are shown. In addition to the resolution of model substances, the TLC-separations of cottonseed, sunflower, olive, peanut and palm kernel oils are given.

Die DC‐Trennung von isomeren und natürlichen Triglycerid‐Gemischen

Die nach der „1,3–2 random distribution” aus den Gesamtfettsauren und den 2-Monoglycerid-Fettsauren berechneten Triglycerid-Strukturen des Olivenoles und des Esteroles werden mit den durch Kombination von Silbernitrat- und Umkehrphasen-Chromatographie experimentell ermittelten Strukturen verglichen. Die Ergebnisse zeigen eine gute Ubereinstimmung mit den theoretischen Werten. Die Triglycerid-Struktur des Esteroles ist der des Olivenoles sehr ahnlich.



The Triglyceride Structures of Olive Oil and of a Glyceride Mixture Synthesised by Esterification of the Olive Oil Fatty Acids



The triglyceride structures of olive oil and the ester oil as calculated on the basis of 1,3–2 random distribution from total fatty acids and 2-monoglyceride fatty acids are compared with those found experimentally by the combination of silver nitrate and reverse phase chromatography. The results show a good agreement with the theoretical values. The triglyceride structure of the ester oil is very similar to that of olive oil.

H. Wessels

Papers

Die Triglycerid‐Strukturen des Olivenöles und des durch Veresterung von Olivenöl‐Fettsäuren hergestellten Glycerid‐Gemisches