The effect of stirring rate (0-300 rpm) on transesterification of Jatropha oil using immobilized lipase is shown in the Fig. 12.7e. As is clear from the figure, there was an increase in ethyl ester formation with increase in mixing intensity. At 300 rpm (rotations per minute), the ethyl ester formation reached 100%. Mixing intensity plays a major role in biodiesel production using immobilized enzyme systems with respect to diffusion and reaction rate. The diffusion problems when using immobilized enzyme systems can be overcome either by reducing the size of immobilized enzymes or by increasing high degree of turbulence around the particle (Shuler and Kargi 1992). However, higher mixing intensity can lead to immobilized enzyme rupture.