Hydrogenation of unsaturated fatty acids

Positionalisomeri tion occurs most often duting partial hydrogenation of unsaturated fatty acids it also occurs ia strongly basic or acidic solution and by catalysis with metal hydrides or organometaUic carbonyl complexes. Concentrated sulfuric or 70% perchloric acid treatment of oleic acid at 85°C produces y-stearolactone from a series of double-bond isomerizations, hydration, and dehydration steps (57). 

Addifion of oils and oilseeds to the diet is another method that has been used to reduce CH4 emissions (Beauchemin et ah, 2008 Eckard et ah, 2010). Lipid addition to the diet may reduce CH4 emissions by hydrogenation of unsaturated fatty acids, enhanced propionic acid production, and protozoal inhibition (Johnson and Johnson, 1995). Reductions in CH4 of >40% have been demonstrated with lipid supplementation... 

The daily output of fecal fat may be regarded as the simplest quantitative measure of the effect of gluten on these patients. The evidence available suggests that the extra fat is derived from dietary fat and mainly represents interference with absorption. There is usually a disproportionate increase of saturated as compared with unsaturated fats (W4). The reason for this is not clear. There may be selective rejection of longer chain and more saturated fats there may also be increased hydrogenation of unsaturated fatty acids (SI). The increase of fat output may occur within a day or 2, or it may be delayed for 10 days or more. There are many possible explanations for this delay. It may require many small insults to the mucous membrane... 

The reaction rate is assumed to be first-order with respect to A and zeroih-order with respect to B, This type of membrane reactors is suitable for such reactions as hydrogenation of unsaturated fatty acids in vegetable oils on Pd and Ni catalysts. 

The hydrogenation of unsaturated fatty acids as part of membrane stmctures of a wide range of lipid classes offers important opportunities [16, 17, 169, 170, 244 f]. Water-soluble catalysts are much more suitable than their lipophilic derivatives, as no solvent vector such as THF or DMSO is needed for the transport of the metal complexes into the membranes. Furthermore, water-soluble catalysts are easier or remove from the still-intact membrane at the end of the reaction, and even the polarity of the catalyst may be controlled by suitable choice of ligand, thus offering a bundle of advantages over monophasic hydrogenations [173]. 

Kemp, P., White, R.W., and Lander, D J. 1975. The hydrogenation of unsaturated fatty acids by five bacterial isolates from the sheep rumen, including a new species. J. Gen. Microbiol. 90, 100-114. 

FA. Therefore, the Working Group does not recommend trans FA to be in the food supply as a result of hydrogenation of unsaturated fatty acids or high-temperature cooking (reused frying oils). 

Systematic investigations of the hydrogenation of unsaturated fatty acids with the use as a reactor of a chromatographic column containing palladium on Celite were carried out by Koman [82] and Harris [83]. 

Unsaturated fatty acids are usually subjected to air oxidation reactions that create rancid taste effects. Therefore, hydrogenation of unsaturated fatty acids reduces these reactions and modifies their functionality. Nevertheless, how can one respond to the critics of hydrogenation who object to it from a health standpoint Through the years nutrition biochemists have been concerned about the trans fatty acids formed during the hydrogenation process (hydrogen gas is bubbled into oils) that produces artificial trans fatty acids that accumulate in body tissues. These artificial fatty acids cause all kinds of diseases because they are foreign to the human immune system and unnatural. 

Hydrogenation of unsaturated fatty acids such as 18 1, 22 1, and 18 2 n-6 proceeds more rapidly in the 1- and 3-positions than in the 2-position (Paulose eta/., 1978 Kaimal and Lakshminarayana, 1979). These distributions are thus a factor in selectivity of hydrogenation. Linolenic (18 3 n-3) acid has a similar distribution to 18 2 n-6 (Ohison et a/., 1975), but on hydrogenation this acid may behave differently from 18 2 n-6 (llsemann et a/., 1979). Rapeseed oil free of excessive sulfur compounds (see below) hydrogenates satisfactorily compared to other commercial vegetable oils (Ahmad and Ali, 1981 El-Shattory eta/., 1981 Roman eta/., 1981). 

Similar considerations apply to the hydrogenation of unsaturated fatty acids (9), which can be represented by... 

Figure 2. Possible products of hydrogenation of unsaturated fatty acid (adapted from deMan, 1990).

When vegetable oil oxidation temperatures were plotted relative to the amounts of total unsaturates, an inverse relationship was observed, i.e., the total amount of unsaturation decreased as the oxidation temperature increased, as seen in fig. 14.7 (R = 0.69). The mechanism of oxidation of vegetable oils is consistent with that of hydrocarbon oxidation. The allylic hydrogens of unsaturated fatty acids are the most susceptible sites for the initiation of oxidation. 

The hydrogenation of unsaturated fatty acids converts double bonds to single bonds. 

Ydnez-Ruiz DR, Scollan ND, Merry RJ, Newbold CJ (2006) Contribution of rumen protozoa to duodenal flow of nitrogen, conjugated linoleic acid and vaccenic acid in steers fed silages differing in their soluble carbohydrate content. Br J Nutr 96 861-869 Yokoama MT, Davis CL (1971) Hydrogenation of unsaturated fatty acids by Treponema (Borrelia) strain Bj5, a rumen spirochete. J Bacteriol 107 519-527... 

Figure 3.23 Scheme of hydrogenation of unsaturated fatty acids and their esters. 

It is well established by now that jjn vivo or jji vitro hydrogenation of unsaturated fatty acid residues of lipids can be carried out using complexes of platinum metal ions (mainly rhodium,ruthenium and palladium) containing as ligands various water soluble phosphines Cl], or Alizarin Red (sodium 1,2-di-hydroxyanthraquinone-3-sulfonate, QS), and this method proved to be a fruitful way for investigating the connection between membrane fluidity and the various properties and functions of... 

The hydrogenation of unsaturated fatty acids of a triacylglycerol in the presence of a Pt or Ni catalyst converts double bonds to single bonds. 

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