Trans Fatty acids occurrence

Fritsche, J., and Steinhart, H. (1998) Analysis, Occurrence, and Physiological Properties of trans Fatty Acids (TFA) with Particular Emphasis on Conjugated Linoleic Acid Isomers (CLA)—A Review, Felt. Lipid 100,190-210. 

Fritsche, J., Steinhart, H. Trans fatty acid content in German margarines. Fett/Lipid 99, 214 (1997) Fritsche, S., Steinhart, H. Occurrence of hormonally active compounds in food a review. Eur. Food Res. Technol. 209, 153 (1999)... 

Fritsche, J. and Steinhart, H., Analysis, occurrence, and physiological properties of trans fatty acids (TFA) with particular emphasis on conjugated linoleic acid isomers (CLA)—A review, Fett/Lipid, 100, 190-210, 1998. 

Wolff, R.L., Precht, D., and Molkentin, J., Occurrence and distribution of tmns-lS l acids in edible fats of natural origin, in Trans Fatty Acids in Human Nutrition, Sebedio, J.L. and Christie, W.W. (Eds), The Oily Press Ltd, Dundee, Scotland, 1998, pp. 1-33. 

Acyl groups are common in bacterial polysaccharides. The parent acids are fatty acids, hydroxy acids, and amino acids. The simplest acid, formic acid, has only been found as the amide. The occurrence of O-formyl groups had been reported, but proved to be incorrect. A-Formyl groups have been found in different polysaccharides for example, in the 0-specific side-chains of the LPS from Yersinia enlerocolitica 0 9, which are composed of 4,6-dideoxy-4-formamido-D-mannopyranosyl residues. The formyl group can assume two main conformations, s-cis (41) and s-trans (42), which are... 

Fatty acid chains may contain no double bonds—that is, be satu rated, or contain one or more double bonds—that is, be mono- or polyunsaturated. When double bonds are present, they are nearly always in the cis rather than in the trans configuration. (See p. 362 for a discussion of the dietary occurrence of cis and trans unsatu- rated fatty acids.) The introduction of a cis double bond causes the I tfatty acid to bend or "kink" at that position (Figure 16.3). If the fatly acid has two or more double bonds, they are always spaced at three carbon intervals. [Note In general, addition of double bonds decreases the melting temperature (Tm) of a fatty acid, whereas j increasing the chain length increases the Tm. Because membrane lipids typically contain LCFA, the presence of double bonds in some fatty acids helps maintain the fluid nature of those lipids.]... 

The structures of these fatty acids are characterized by (a) the presence of an olefinic bond between carbon atoms 9 and 10 (counting from the carboxyl end) and (b) the occurrence of a cis configuration rather than a trans configuration at the double bond. Fatty acids are known in which a single double bond occurs at other positions and in which a trans configuration is present, but these are relatively rare. 

The occurrence of cis-double bonds hampers dense packing. Trans-double bonds do not have this effect elaldic acid (which has such a bond) packs like stearic acid. The effect of the cis-bond in the hydrocarbon chain is shown in fig. 3.1 lb, where it is observed that in the condensed phase the molecular area of Cj COOH increases from 0.28 nm for the fully saturated hydrocarbon chain (stearic acid), via 0.40 nm for the single unsaturated chain (oleic acid) to 0.49 nm for the doubly conjugated unsaturated chain (linoleic acid). In line with this, the collapse point, i.e. the value for where the monolayer breaks down to form a multilayer. Increases with decreasing degree of saturation. The pressure corresponding to the collapse point is lower when the fatty acid contains more double bonds (see the arrows in the figure). 

The established major pathways of BH describe the formation of VA but do not account for the occurrence of other 18 1 fatty acids identified in rumen digesta (Katz and Keeney, 1966) (Table II). Following detection of a large number of positional trans isomers of dienoic and monoenoic fatty acids, after linoleic acid was incubated with rumen contents, Ward et al. (1964)... 

Some plant species synthesise fatty acids with one or more double bonds of the frans-configuration (e.g. frans-9,frans-12-octadecenoic acid), with conjugated double bond systems (e.g. cis-9,trans-, trans- Z-octadecatrienoic or a-eleostearic acid), or with acetylenic bonds (e.g. octadec-c/s-9-en-12-ynoic or crepenynic acid). The natural occurrence of such fatty acids has been reviewed [71,856],... 

In this study, the occurrence and the growth temperature-dependent alteration of trans-unsaturated fatty acid in Vibrio ABE-1 are described. It is suggested that the isomerization of cis/trans unsaturation of fatty acids may result in the growth temperature-dependent shift in the phase transition temperature of the membrane phospholipids. 

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