Hydrolysis of triglyceride by solid phase lipolytic enzymes of Rhizopus arrhizus in continuous reactor systems

Continuous hydrolysis of triglyceride in organic solvent systems using Rhizopus arrhizus mycelia as a source of insolubilized lipase has been studied in packed-bed and stirred-tank reactors. Typically a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di-isopropyl ether gave a fatty acid yield of 45% at 30°C. The optimum water concentration was found to be 0.17% (w/v) except under conditions of high oil feed concentration and high yield where no optimum was established. No temperature optimum was observed over the range 20–55°C. Calculated activation energies of 13–20 kJ/mol, depending on temperature, were lower, while K_m(app) values of 0.1–0.3M were higher than those for hydrolysis in conventional aqueous emulsion systems. No evidence of any significant diffusional limitation, which could account for these values, was obtained. The mycelia showed a loss of activity of 0.6–1.0%h at 30°C. The packed bed proved markedly superior to the stirred tank for this system.