CATALYTIC BEHAVIOR OF LIPASE FREE AND IMMOBILIZED IN BIPHASIC MEMBRANE REACTOR WITH DIFFERENT LOW WATER-SOLUBLE SUBSTRATES

The catalytic activity and reaction rate of lipase have been studied u sing the biocatalyst free in an organic/aqueous emulsion and immobiliz ed in a biphasic organic/aqueous membrane reactor. The first reaction system was realized in a stirred tank reactor. The other was obtained by immobilizing the enzyme in the sponge layer of an asymmetric capill ary membrane and recirculating the two phases along the two separate c ircuits of the membrane module. The performance of the reactors has be en studied using two different low water-soluble substrates: triglycer ides present in commercial olive oil and (R,S)-cyanomethyl-[2-(4-isobu tylphenyl)propionate] (CNE). The effects of substrate viscosity and fl ow dynamics conditions, such as organic phase flow rate, on the biphas ic membrane reactor performance have been evaluated on the basis of ob served reaction rate and catalytic activity of free and immobilized li pase for both substrates. It has been observed that free lipase showed higher catalytic activity with olive oil, while immobilized lipase sh owed higher catalytic activity with CNE which has a lower viscosity th an olive oil. The increase of organic phase flow rate negatively affec ted the reactor performance, with a minor effect when using CNE rather than olive oil. The influence of temperature on the biocatalyst perfo rmance with the two substrates has also been investigated. The optimal temperature value of lipase was different for the two substrates: 28 degrees C with CNE and 40 degrees C with olive oil.