Methode zur Bestimmung dimerer Säuren in Ölen und Fetten

Lipid oxidation. Part 4. Products of thermooxidative polymerization of vegetable oils

The thermal treatment of vegetable oils was studied by gel chromatography on packings of styrene-divinylbenzene copolymers. Unlike oils with a lower content of polyene acids, those with a high content of polyene acids contained a larger amount of higher oligomers of fatty acids. The gel chromatography of fatty acid methyl esters from heated oils allowed the determination of the ratio of intra- and intermolecular bonds arising by polymerization reactions. The results of determination of the iodine value of products were correlated with the data obtained by gel chromatography.

[Behavior of fat constitutents during refining. 8. Determination of polymeric fatty acids in rape seed oil and their behavior during refining]

1. Studies on rape-seed oil have shown that the determination of oxypolymers by means of the method according to Rost (determination of fatty acids insoluble in petroleum ether) yields unsatisfactory results. By way of contrast, the gravimetric determination (after isolation of the polymers via the non-urea adduct fatty acid methyl esters and thin-layer chromatographic separation), as proposed by the authors, permits to obtain results of good reproducibility and to determine thermopolymers and oxypolymers separately. 2. During the refining of rape-seed oil, it was observed that its polymer content decreased considerably on bleaching, and increased on deodorizing.