The determination of polymers in fats and oils

Supercritical fluid extraction of fat from ground beef: effects of water on gravimetric and GC-FAME fat determinations

This study investigated the supercritical carbon dioxide (SC-CO(2)) extraction of fat from ground beef and the effects of several factors on the gravimetric determination of fat. The use of ethanol modifier with the SC-CO(2) was not necessary for efficient fat extraction; however, the ethanol did increase the coextraction of water. This coextraction of water caused a significant overestimation of gravimetric fat. Oven-drying ground beef samples prior to extraction inhibited the subsequent extraction of fat, whereas oven-drying the extract after collection decreased the subsequent gas chromatographic fatty acid methyl ester (GC-FAME) fat determination. None of the drying agents tested were able to completely prevent the coextraction of water, and silica gel and molecular sieves inhibited the complete extraction of fat. Measurements of collection vial mass indicated that CO(2) extraction/collection causes an initial increase in mass due to the density of CO(2) (relative to displaced air) followed by a decrease in vial mass due to the removal of adsorbed water from the collection vial. Microwave-drying of the empty collection vials removes approximately 3 mg of adsorbed water, approximately 15-20 min is required for readsorption of the displaced water. For collection vials containing collected fat, microwave-drying effectively removed coextracted water, and the vials reached equilibration after approximately 10-15 min. Silanizing collection vials did not significantly affect weight loss during microwave-drying. SC-CO(2) can be used to accurately determine fat gravimetrically for ground beef, and the presented method can also be followed by GC-FAME analysis to provide specific fatty acid information as well.

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.

Pentane from thermal decomposition of lipoxidase-derived products

Thermal decomposition of 13-hydroperoxyoctadeca-9,11-dienoic acid yields hydrocarbons as part of the scission products. Pentane is formed predominately and to the practical exclusion of all other short-chain hydrocarbons.