Trans Fatty acids absorption

Infrared spectra of fats and oils are similar regardless of their composition. The principal absorption seen is the carbonyl stretching peak which is virtually identical for all triglyceride oils. The most common appHcation of infrared spectroscopy is the determination of trans fatty acids occurring in a partially hydrogenated fat (58,59). Absorption at 965 - 975 cm is unique to the trans functionaHty. Near infrared spectroscopy has been utilized for simultaneous quantitation of fat, protein, and moisture in grain samples (60). The technique has also been reported to be useful for instmmental determination of iodine value (61). 

Trans fatty acids are present in the diet in esterified form, mainly in triacylglycerols but those from ruminant sources may also be present in phospholipids. Before absorption into the body, triacylglycerols must be digested by pancreatic lipase in the upper small intestine. There is no evidence of differences in the hydrolysis and absorption of trans fatty acids, in comparison with that of cis fatty acids. Trans fatty acids are transported from the intestine mainly in chylomicrons, but some are also incorporated into cholesteryl esters and phospholipids. 

Modulation of epidermal hpid biosynthesis has been reported to boost dmg delivery. It has also been suggested that it is both the hydrophobic nature of the lipids as well as their tortuous, extracellular localization that are responsible for the restriction in the transport of most molecules across the stratum corneum. The function of this barrier depends on three key lipids cholesterol, fatty acid, or ceramides. Delays of synthesis ceramides in the epidermis have been reported as means of barrier perturbation. Inhibitors of lipid synthesis were used to enhance the trans-dermal delivery of lidocaine or caffeine. Alteration of barrier function was produced by either the fatty acid synthesis inhibitor 5-(tetradecyloxy)-2-fiirancarboxylic acid, the cholesterol synthesis inhibitor fluvastatin, or the cholesterol sulfate, which resulted in a further increase in lidocaine absorption (33). 

Jart (1960) has recorded spectra of many different fatty acids and fatty acid esters in carbon disulfide solution. Stress was laid on the study of the trans absorption at 962cm and absorptivities of the pure substances at the trans maximum were calculated. Beer s law applied for concentrations up to 2(X) g of substance per liter of solution. This worker used a baseline method for the quantitative determination of trans monoene fatty acids in mixtures with saturated acids and cis forms of unsaturated fatty acids and fatty acid esters. Unlike the cis compounds and the saturated compounds, trans compounds display a considerable absorption at 962 cm (CH bending about the trans C=C group). 

Szonyi et al. (1962) have described a differential infrared spectrophotometric method for the determination of trans unsaturation in fats. The method utiUzes absorption at 965 cm which is due to C—H out-of-plane deformation vibrations of trans unsaturated compounds. The method is rapid, accurate, and directly appUc-able to the determination of trans unsaturation in triglycerides. It is applicable to samples which contain low concentrations of trans acids (down to 2%) and also to samples with fatty acids of mixed chain length. The absorptivities used in the calculations for this method are those established by Shreve et al. (19506). 

Eremin et al. (1965) have precipitated carbohydrate material with ethanol after alkaline hydrolysis of cultures of Whitmore s bacillus Pseudomonas pseudomailer), Pasteurella pestis, and Vibrio comma, and have subjected these polyoses to infrared spectroscopy. All spectra had strong absorption at 1660 and 1550 cm the former was related to double-bond vibrations and the latter was associated with stretching vibrations of C—N. The latter absorption was almost completely absent in the spectrum of a complex from V. comma. Absorption at 970 cm (the C=C double bond in the trans position) and traces of absorption at 790 cm characteristic of the 1 — 3 bond were always present. A polysaccharide from the cell wall of P. pestis had a wide band at 1170-1000 cm the low intensity bands at 1190 and 1160cm indicated the presence of P—O—Me and P—O—Et groups. The spectrum of a complex from Whitmore s bacillus differed from the others by the presence of a band at 1735 cm due to esters of fatty acids. 

The esters are colorless, liquid oils. The purity is obvious from the gas chromatographic analyses (Fig. 13). Hydrogenation of the diinoic acids slightly exceeds the dienoic acid stage, as indicated by the presence of traces of monoenoic and saturated fatty acids. The infrared spectra (Fig. 14) show no absorption in the 10.4 i region, thus excluding trans double bonds. The ultraviolet spectra of the dienoic fatty acids are shown in Fig. 15. (See also Table IX.)... 

In food, CLA is found in milk fat, the tissue fat of ruminant animals, and products derived from them, although there are exceptions. About 90% of the CLA is represented by the cis-9, trani-11-isomer or rumenic acid (RA) (4). This isomer is produced in the rumen by the action of a linoleic acid isomerase on dietary linoleic acid as a first step in the biohydrogenation process. Further hydrogenation produces trans- - %. or vaccenic acid (VA), the predominant trans monounsaturat-ed fatty acid of milk and animal tissue fat. The major polyunsaturated fatty acids of pasture, a-and y-linolenic acid, cannot be converted to RA, but they do produce VA. A proportion of RA and VA escape further hydrogenation in the rumen and after absorption pass via the circulatory system to adipose tissue and the mammary gland where A -desaturases convert VA to RA. About 70% of RA in milk fat is produced by this pathway (5). 

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