15E-21 |
Enzymatic polyesterification of glycerol with conjugated linoleic acid and other free fatty acids in hexane |
C. E. MARTINEZ1, J. C. Vinay2, M. R. Brieva3, C. G. Hill, Jr.4, and H. S. Garcia2. (1) Coordinación de Posgrado e Investigación, Instituto Tecnologico de Tuxtepec, Av. 5 # 1084, Fracc. Costa Verde, Tuxtepec, Oax., Mexico, (2) UNIDA, Instituto Tecnologico de Veracruz, M.A. de Quevedo # 2779, Col. Formando Hogar, Veracruz, Ver., 91897, Mexico, (3) Facultad de Quimica, Universidad de Oviedo, Av. Pedro Rasaven # 15 1F, Oviedo, Asturias, 23007, Spain, (4) Dept. of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Dr., Madison, WI 53706 Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid characterized by double bonds at positions 8 and 10, 9 and 11, 10 and 12, or 11 and 13. The cis-9, trans-11 and trans-9, cis-11 isomers have been associated with important biological activities, including anticarcinogenic and antiatherogenic activities. One route by which CLA might be incorporated in human diets involves the production of fats and oils enriched in CLA residues. These materials can be used to manufacture nutraceutical dairy spreads and frozen desserts, designed for consumption by individuals who are at risk for those disease conditions against which CLA has demonstrated bioactivity. The objective was to study the polyesterification of glycerol with CLA and other free fatty acids in hexane solution to produce mixtures of monoacylglycerols (MAG) and diacylglycerols (DAG) that can be employed as food emulsifiers. A free fatty acid mixture containing CLA was prepared by chemical isomerization of sunflower oil. Reactions were carried out by mixing appropriate amounts of lipases, glycerol and the CLA mixture in hexane at temperatures from 30 to 50°C. Molar ratios of the CLA mixture to glycerol were 1:1 and 1:2. The extent to which the CLA was esterified was determined by GC. Glyceride groups were analyzed by HPLC. Esterification of CLA was greater than 90% in 4 h at 50°C when the lipase from R. miehei was used to mediate the reaction of a 1:1 mole ratio of substrates. Lipase from C. antarctica produced similar extents of esterification under the same conditions. At 50°C, both immobilized enzyme preparations produced mixtures containing high concentrations of DAG and MAG from a feedstock containing a 1:1 mole ratio of substrates and 5% [w/w] immobilized enzyme. The product mixtures of DAG and MAG containing CLA residues can be utilized as emulsifiers in food systems.
Session 15E, Nutraceuticals & Functional Foods I
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