H. F. de Castro

Evaluation of different approaches for lipase catalysed synthesis of citronellyl acetate

Three different approaches for lipase catalysed synthesis of citronellyl acetate by a commercial available immobilized lipase have been studied: a) direct esterification reaction of citronellol with acetic acid; b) alcoholysis of butyl acetate with citronellol and c) transesterification of citronellyl butyrate with butylacetate. Heptane was used as solvent for all the experiments. The extent of reaction occurred in the order alcoholysis>transesterification>esterification. Substrate partitioning between the immobilization support and the organic medium seems to greatly influence the catalytic performance of this enzyme preparation. Production of citronellyl acetate, was found to be dependent on the partition coefficient of the acyl donor which account the greatest value for the acetic acid.

Physico-chemical, spectroscopical and thermal characterization of biodiesel obtained by enzymatic route as a tool to select the most efficient immobilized lipase

Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization and used to perform the reactions under the following operational conditions: beef tallow-to-ethanol molar ratio of 1:9, 45oC and 400 units of enzymatic activity per gram of fat. Products, characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosimetry, thermogravimetry and 1H NMR spectroscopy, suggested that the biodiesel sample obtained in the reaction catalyzed by Burkholderia cepacia lipase has the best set of properties for fuel usage.