Transesterification lipid

Huang, Y-S and Akoh, CC (1996) Enzymatic synthesis of structured lipids transesterification of triolein and caprylic acid ethyl ester. J. Am. Oil Chem. Soc., 73, 245-250. 

Snyder, King, Jackson [68] Van Eijs et al. [69] Lipase esterification of hexanoic acid with hexanol Methylation of lipids Transesterification Supercritical fluids CO2 Continuous and extractive... 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

The lipases demonstrated very high stability in media partially or totally composed of organic solvent. In such media, the lipases catalyze esterification, transesterification, and resolution of enantiomers [19,45,75,97-100]. Nevertheless, several biphasic systems (organic-aqueous) are used for hydrolysis of lipid and fats [7,34,101]. Kinetic studies in biphase media or in inverted micelles demonstrate that the lipase behavior is different... 

Dworzanski, J. R Berwald, L. McClennen, W. H. Meuzelaar, H. L. C. Mechanistic aspects of the pyrolytic methylation and transesterification of bacterial cell wall lipids. /. Anal. Appl. Pyrolysis 1991,21,221-232. 

However, acids can simultaneously catalyze both esterification and transesterification, therefore they can directly produce biodiesel from low-cost lipid feedstocks. 

Compared to the base-catalyzed synthesis of biodiesel, fewer studies have dealt with the subject of acid-catalyzed transesterification of lipid feedstocks. Among acid catalysts, sulfuric acid has been the most widely studied. In the previously mentioned work of Freedman et al., the authors examined the transesterification kinetics of soybean oil with butanol using sulfuric acid. The three reaction regimes observed (in accordance with reaction rate) for base-catalyzed reactions were also observed here. A large molar ratio of alcohol-to-oil, 30 1, was required in this system in order to carry out the reaction in a reasonable time. As expected, transesterification followed pseudo-first-order kinetics for the forward reactions (Figure 2), while reverse reactions showed second-order kinetics. 

Currently, nearly all biodiesel is produced via homogeneous catalysis. The use of homogeneous catalysts allows carrying out the transesterification of lipid... 

In order to enhance the potential of synthetic reactions of lipids and the transesterification in organic solvents, a fungal lipase from Phycomyces nites was chemically modified. The promotion of dispersibility in orgaiuc solvents resulted in a much higher reactivity. Chemically modified lipases showed higher reactivity than unmodified lipase when they were utilized for the transesterification of triglycerides and other lipids. The initial rate of transesterification in organic solvents by modified lipase was 40 times faster than that of unmodified lipase. Chemically modified lipase was also found applicable for the syndesis of other fatty acids esters. 

This three-step process for transferring fatty acids into the mitochondrion—esterification to CoA, transesterification to carnitine followed by transport, and transesterification back to CoA—links two separate pools of coenzyme A and of fatty acyl-CoA, one in the cytosol, the other in mitochondria These pools have different functions. Coenzyme A in the mitochondrial matrix is largely used in oxidative degradation of pyruvate, fatty acids, and some amino acids, whereas cytosolic coenzyme A is used in the biosynthesis of fatty acids (see Fig. 21-10). Fatty acyl-CoA in the cytosolic pool can be used for membrane lipid synthesis or can be moved into the mitochondrial matrix for oxidation and ATP production. Conversion to the carnitine ester commits the fatty acyl moiety to the oxidative fate. 

There are basically two mechanisms to convert the fatty acids in a complex lipid to fatty acid methyl esters (FAMEs) methylation following hydrolysis of the fatty acids from the complex lipids, or direct transesterification. The first mechanism involves saponification (alkaline hydrolysis) in which the ester bond is cleaved between the fatty acid and the glycerol moiety (e.g., triacylglycerols and phospholipids) under heat and in the presence of an alkali (usually sodium hydroxide), followed by methylation performed in the presence of an acidic catalyst in methanol. Direct transesterification is usually a one-step reaction involving alkaline or acidic catalysts. 

On the other hand, BF3 (see Basic Protocol 1), as well as other acidic catalysts, will change the double-bond configuration of fatty acids that contain conjugated dienes. As research on conjugated linoleic acid (CLA) and other conjugated fatty acids becomes more popular, it is essential not to provide misinformation about compositional analysis due to improper application of a methylation protocol (Li and Watkins, 1998). The basic catalysts perform better on lipids rich in fatty acids with unique conjugated diene structures. Isomerization and artifacts are not produced when sodium methoxide or TMG are used as transesterification agents... 

Transesterification, fatty acid analysis of lipids, 437, 439 Triacetin, lipase assays, 378 Triacylglycerol acylhydrolase, 371, 375, 378. See also Lipases Triacylglycerols, 432 Tributyrin, lipase assays, 378 Trichloroacetic acid (TCA) solubility index for protein hydrolysis, 152 in TBARS determination, 548-550 Trienes, conjugated, determination of, 515-517, 523-524, 526, 528 Trifluoroacetic acid (TFA), for determination of neutral sugars, 721-722, 724-725, 729-730... 

Dasgupta, A., Banerjee, P. and Malik, S., Use of microwave irradiation for rapid transesterification of lipids and accelerated synthesis of fatty acyl pyrrolidides for analysis by gas chromatography-mass spectrometry study of fatty acid profiles of olive oil, evening primrose oil, fish oils and phospholipids from mango pulp,... 

The lipid feedstock may contain variable proportions of free fatty acids (FFA), which should be converted in esters before transesterification. Otherwise, the formation of soaps occurs by reaction with the hydroxide catalyst, as follows ... 

The methods described above have been used principally to quantify FFAs in cheese, but can be used for other milk products with some slight modifications. All the above methods use internal standards (typically FFAs which are not present in milk fat), and the recovery of all FFAs is based on the recovery of these internal standards. It is best to use both volatile and non-volatile FFAs as internal standards. Currently, the International Standard for the extraction of lipids and lipo-soluble compounds from milk and milk products is ISO 14156 (ISO, 2001) and involves solvent extraction. Determination of the fatty acid composition of milk fat involves the preparation of fatty acid methyl esters (FAME) by transesterification (ISO, 2002a), followed by quantification by GC (ISO, 2002b). 

In the food industry, lipases are used in lipid modification processes. In these processes the texture, digestibility, or physical properties of natural lipids are modified by lipase-catalyzed transesterification reactions with lipids other than the original fatty acids. In the baking industry, lipases are used to influence the quality of bread through modification of the wheat flour lipids. Finally lipases are used for flavor enhancement of cheese in the dairy industry. 

Use of Enzymes Lipases are widely used in the processing of fats and oils as catalysts of a number of important lipid reactions, such as hydrolysis, esterification, and transesterification reactions (174). There are a wide number of lipases obtained from different sources, which are available commercially in their free/ crude or immobilized form. However, enzymes with a higher tolerance of pressure would be welcomed, and more research is needed to hopefully develop such enzymes (i.e., genetic engineering or marine sources of the deep ocean). 

Lipase-catalyzed hydrolysis of the vitamin esters in food samples in SCCO2 has been investigated as a pretreatment step in the analytical determination of vitamins in food samples (216, 217). Lipase-catalyzed transesterification of oils with methanol have been used for the determination of total fat content in lipid-containing samples such as oilseeds and meat samples (218, 219) and for the determination of fatty or resin acid content of tall oil products (220). Esterification of fatty acids with methanol in SCCO2 has been reported for total fatty acid analysis of soapstock (221). 

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