Dimeric triglycerides

Zeman and Scharmann (57) reported the presence of 0.3% nonpolar dimers composed of diunsaturated bicyclic and tetraunsaturated acyclic structures in peanut oil subjected to thermal and oxidative action. Perrin et al. (58) analyzed samples from two different peanut and sunflower oils oxidized by deep fat frying to a stable foam formation. They reported the presence of dimers at levels between 12.1 % and 12.9% of the oxidized mixtures. Peanut oil oxidized by deep fat frying before and after stable foam formation yielded 7.8% and 14% dimers, respectively. Gere et al. (59) reported nonpolar and polar dimeric triglycerides in sunflower oil used in deep fat frying. 

Kupranycz et al. (60) reported the presence of dimeric triglycerides in various butterfat samples oxidized at 185°C in the presence of air for 8 and 16 h. Nonpolar and polar dimeric TGs were found in lard samples used in deep fat frying (61). 

A. Zambon, I. Schmidt, U. Beisiegel and J.D. Brunzell, Dimeric lipoprotein lipase is bound to triglyceride-rich plasma lipoproteins, J. Lipid Res. 37 (1996) 2394-2404. 

Triglyceride dimers in oil. Dimers, together with polymers, are formed during heating of oils. It is claimed that unrefined oils contain no detectable (<0.5%) dimers and that, if a detectable level is found, this may be caused by adulteration with a refined oil (Gertz and Klostermann, 2000). This method would probably only detect gross adulteration and not low levels. 

As shown in Figure 2-23, oil breakdown during frying can be caused by oxidation and thermal alteration. Oxidation can result in the formation of oxidized monomeric, dimeric, and oligomeric triglycerides as well as volatile compounds including aldehydes, ketones, alcohols, and hydrocarbons. In addition, oxidized sterols may be formed. Thermal degra-... 

DPTG dimeric and polymeric triglycerides Viscosity for Liq. Oiis 27... 

Fats and oils (triglycerides) from plants and animals are renewable sources of chemicals, but the amounts of the chemicals made from them are small compared with those made from petroleum and natural gas. This may change if biodiesel fuel (e.g., ethyl oleate) made by the alcoholysis of oils becomes common. Such esters may be useful as environmentally friendly solvents.50 Unsaturated oils, such as linseed oil, are the basis of oil-based paints, which cure by cross-linking through oxidation by air. Soaps are the potassium or sodium salts of the long-chain fatty acids obtained by the hydrolysis of the triglycerides. The dibasic dimer fatty acids obtained by the dimerization of oleic and linoleic acids (both Cig acids) are made into oligomeric fatty amides which are used to cure epoxy resins. The un-... 

That the radiolysis of triglycerides in meats involves a common set of radicals reacting to form stable products corresponding to their precursor fatty acids is shown by chromatographically analyzing product yields in relation to fat composition [14, 62, 63], Radicals other than those described and formed by C-O and C-C bond scission in the fetty acid chain lead to distinctive and predictable products. The acyl and acyloxy radicals can react by abstraction, combination, and even dissociation to produce corresponding alkyl radicals along with CO and CO2. The alkyl radical reaction possibilities, as shown in for the Ci7 radical, include abstraction, dimerization, and disproportionation, which forms a double bond at the terminal carbon ... 

Tocopherols and the mechanism of their anti-oxidant properties continue to interest chemists. Potassium superoxide, in the presence of dicyclohexyl-18-crown-6, converts the model compound 2,2,5,7,8-pentamethylchroman-6-ol (121) into its 4a,5 7,8-diepoxide (122). Benzoyl peroxide and the peroxides which are present in sunflower oil oxidize a-tocopherol to the phenoxyl radical, according to evidence obtained by e.s.r. and i.r. spectroscopy. In another study, (-l-)-5-tocopherol was oxidized, above 180 C, in various fats to the dimers (123) and (124). The effects of temperature and the nature of the triglyceride on the relative amounts of the two dimers were studied. 

Dobarganes, M.C. and Marquez-Ruiz, G. 1996. Dimeric and higher oligomeric triglycerides, in Deep Frying, Perkins, E.G. and Erickson, M.D., Eds., Champaign, IL AOCS Press, 89-111. 

Dimeric and oligomeric triglycerides Volatile compounds (e.g., aldehydes, ketones, alcohols, esters, hydrocarbons, and aromatic compounds)... 

Brassica campestris/Aleurites fordi oil copolymer Candelilla synthetic Caprylic/capric triglyceride Carboxymethyl chitin Cl0-30 cholesterol/lanosterol esters Cetearyl behenate Cetearyl stearate Ceteth-80 Cetyl ricinoleate Cholesterol Coco-rapeseedate Collagen Collagen amino acids Coneflower (Echinacea pallida) extract Coneflower (Echinacea purpurea) extract Connective tissue extract Copper acetylmethionate Copper PCA Cornflower (Centaurea cyanus) extract Diisostearyl dimer dilinoleate... 

The bodying or oxidation of fatty acids and oils is easily monitored by SEC in tetrahydrofuran, and this has been widely used in the food industry. Jensen and Moller [46] separated feed fat samples into monomeric triglycerides and dimers on a 500A Styragel column, eluting with tetrahydrofuran (0.3 mL min" ) and using RI detection. Samples were also hydrolysed, and the resulting acids methylated and separated as before into monomeric, dimeric and trimeric fatty acid esters. The fractions obtained were analysed by mass... 

The production of oxidative dimers and triglyceride oligopolymers by oxidation prior to deodorization decreases the stability of oils. Flavor and oxidative stability of soybean oil correlates with the concentration of oxidative dimers determined chromatographicaUy. The oxidative stabihty of vegetable oils can therefore be markedly improved, if any oxidation products present in partially processed oils can either be removed or chemically reduced to stable hydroxides before deodorization. 

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