(Xu et al., 1998b). The process contained a substrate tank including heating and
stirring, a product tank equipped with cooling system, a gear or metering pump,
flow and pressure controls, and a packed enzyme bed containing a jacket. The water
content control was assisted by water addition to the feeding tank, stirring, and tem-
perature control. It was found that the steady production could be obtained at optimal
conditions. Short path distillation was optimized for the downstream purification of
specific structured lipids. A one-stage reaction was usually used because 65–75 %
incorporation atsn-1,3 positions could be obtained. When higher incorporation of
acyl donors is necessary, two stages could be conducted, though this of course re-
duced the productivity of the process.
For a membrane-applied process, membranes have been used as a lipase carrier
(Balcao et al., 1996a; Balcao and Malcata, 1998), lipase filter (Basheer et al., 1995c),
free fatty acid separation medium (Keurentjes, 1991; Schroen, 1995), and reaction
and separation system (X. Xu et al., unpublished results). So far, both high flux and
high selectivity (rejection) of membranes are impossible to achieve for the separation
of free fatty acids from triacylglycerols (Snape and Nakajima, 1996). However, in a
specifically defined application, fluxes could be made compatible with the reaction
systems if the membrane reactors were to be properly designed and operated.
11.9 References
Abraham, G. (1988), Mass transfer in Bioreactors, in Applewhite, T.H. (Ed.),Proceedings of World Con-
ference on Biotechnology for the Fats and Oils Industry, AOCS Press, Champaign, IL, pp. 226–229.
Akoh, C.C. (1996), Enzymatic Modification of Lipids, in McDonald, R.E., Min, D.B. (Eds),Food Lipids
and Health, Marcel Dekker, New York, pp. 117–138.
Balcao, V.M., Malcata, F.X. (1998), Interesterification and acidolysis of butterfat with oleic acid byMucor
javanicuslipase: changes in the pool of fatty acid residues,Enzyme Microb. Technol. 22 , 511–519.
Balcao, V.M., Vieira, M.C., Malcata, F.X. (1996a), Adsorption of protein from several commercial lipase
preparations onto a hollow-fiber membrane module,Biotechnol. Prog. 12 , 164–172.
Balcao, V.M., Paiva, A.L., Malcata, F.X. (1996b), Bioreactors with immobilized lipases: state of the art,
Enzyme Microb. Technol. 18 , 392–416.
Balcao, V.M., Malcata, F.X. (1996), Reactors with immobilized lipases: mathematical modeling, in Mal-
cata, F.X. (Ed.),Engineering of/with Lipases, Kluwer Academic Publishers, Dordrecht, The Nether-
lands, pp. 435–454.
Basheer, S., Mogi, K., Nakajima, M. (1995a), Interesterification kinetics of triglycerides and fatty acids
with modified lipase in n-hexane,J. Am. Oil Chem. Soc. 72 , 511–518.
Basheer, S., Snape, J.B., Mogi, K., Nakajima, M. (1995b), Transesterification kinetics of triglycerides for
a modified lipase in n-hexane,J. Am. Oil Chem. Soc. 72 , 231–237.
Basheer, S., Mogi, K., Nakajima, M. (1995c), Development of a novel hollow-fiber membrane reactor for
the interesterification of triglycerides and fatty acids using modified lipase,Process Biochem. 3 0,
531–536.
Bornscheuer, U.T., Kazlauskas, R.J. (1999),Hydrolases in Organic Synthesis – Regio- and Stereoselective
Biotransformations, Wiley-VCH, Weinheim.
Bornscheuer, U.T. (1995), Lipase-catalyzed syntheses of monoacylglycerols,Enzyme Microb. Technol.
17 , 578–586.
Bozeix, F., Monot, F., Vandecasteele, J.-P. (1992), Strategies for enzymatic esterification in organic sol-
vents: comparison of microaqueous, biphasic, and micellar systems,Enzyme Microb. Technol. 14 ,
791–797.
Brady, R.L., Brzozowski, A.M., Derewenda, Z.S., Dodson, E., Dodson, G., Tolley, S., Turkenburg, J.P.,
Christiansen, L., Huge-Jensen, B., Norskov, L., Thim, L., Menge, U. (1990), A serine protease triad
forms the catalytic center of a triacylglycerol lipase,Nature 343 , 757–770.