ENZYME-CATALYZED INTERESTERIFICATION OF TRIGLYCERIDES IN SUPERCRITICAL CARBON-DIOXIDE

The interesterification of trilaurin and myristic acid, catalyzed by a 1,3-specific lipase from Rhizopus arrhizus, has been investigated in supercritical carbon dioxide. Experimental data have been obtained from reactions conducted in a continuous-flow packed-bed reactor containing lipase covalently attached to glass beads. The reaction rate is not influenced by mass-transfer limitations over the range of flow rates studied, and lipase retains full activity at 1400 psi and 35-degrees-C for up to 80 h. The carbon dioxide water content does not affect the intrinsic activity of the enzyme, but a higher water concentration causes a greater degree of unwanted hydrolysis. The selectivity of the reaction for interesterification over hydrolysis improves at higher pressures as the extent of hydrolysis reaction is reduced. The activity and stability of lipase in supercritical carbon dioxide are similar to those in organic liquid solvents.