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Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei.

Hari Krishna, S. and Divakar, S. and Prapulla, S. G. and Karanth, N. G. (2001) Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei. Journal of biotechnology, 87 (3). pp. 193-201. ISSN 0168-1656

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Abstract

The effects of important reaction parameters for enhancing isoamyl acetate formation through lipase-catalyzed esterification of isoamyl alcohol were investigated in this study. Increase in substrate (acid) concentration led to decrease in conversions. A critical enzyme concentration of 3 g l(-1) was detected for a substrate concentration of 0.06 M (each of alcohol and acid). Solvents with partition coefficient higher than 1000 (log P>3.0) supported enzyme activity to give high conversions. Acetic acid at higher concentrations could not be esterified easily probably owing to its role in lowering the microaqueous pH of the enzyme. Extraneous water/buffer addition decreased the isoamyl acetate yields slightly ( approximately 10%) at 0.005-0.01% v/v of the reaction mixture and drastically (>40%) at above 0.01% v/v. Buffer saturation of the organic solvent employed improved esterification (upto two-fold), particularly at moderately higher substrate concentrations (>0.18 M). Employing acetic anhydride instead of acetic acid resulted in a two-fold increase in the yields (at 0.25 M substrate). Use of excess nucleophile (alcohol) concentration by increasing the alcohol/acid molar ratio resulted in higher conversions in shorter duration (upto eight-fold even at 1.5 M acetic acid). Yields above 80% were achieved with substrate concentrations as high as 1.5 M and more than 150 g l(-1) isoamyl acetate concentrations were obtained employing a relatively low enzyme concentration of 10 g l(-1). The operational stability of lipase was also observed to be reasonably high enabling ten reuses of the biocatalyst.

Item Type: Article
Subjects: 600 Technology > 08 Food technology > 16 Nutritive value > 05 Enzymes
600 Technology > 08 Food technology > 15 Flavour/Fragrance/Perfumes
Divisions: Fermentation Technology and Bioengineering
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 04 Aug 2008 09:27
Last Modified: 25 Sep 2018 09:01
URI: http://ir.cftri.com/id/eprint/2134

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