Enzymatic synthesis of medium-chain triglycerides in a solvent-free system.
The synthesis of tricaprylin, tricaprin, trilaurin, and trimyristin in a solvent- free system was conducted by mixing a commercial immobilized lipase (Lipozyme IM 20, Novo Nordisk, Bagsvaerd, Denmark) with the organic reactants (glycerol and fatty acids) in a 20-mL batch reactor with constant stirring. In a first set of experiments, the effect of water concentration (0-6%) on the reaction conversion was shown to be negligible. In a second set of experiments, the effects of temperature (70-90 degrees C), fatty acid/glycerol molar ratio (1-5), and enzyme concentration (1-9% [w/w]) on the reaction conversion were determined by the application of a 3 x 3 experimental design. The reactions were carried out for 26 h and the nonpolar phase was analyzed by gas chromatography (GC). Appreciable levels of medium-chain triglycerides were achieved, except for tricaprylin. For the triglyceride production, higher selectivity was attained under the following conditions: molar ratio of 5, enzyme concentration of 5 or 9% (w/w) and temperatures of 70 degrees C (tricaprin), 80 degrees C (trilaurin), and 90 degrees C (trimyristin). Statistical analysis indicated that the fatty acid/glycerol molar ratio was the most significant variable affecting the synthesis of triglycerides.
Instituto de Química da Universidade do Estado do Rio de Janeiro and COPPE, Universidade Federal do Rio de Janeiro, P.O. Box 68502, CEP 21945-970, Rio de Janeiro, RJ, Brazil.
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Langone
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Sant'Anna