LAUSR

Bovine pancreatic lipase was immobilized onto N-succinyl-chitosan beads by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC)/N-hydroxysuccinimide (NHS) as the activating agent. The immobilized lipase was characterized by Fourier transform infrared spectra and scanning electron microscopy. The activity of the immobilized lipase obtained under the optimized immobilization conditions was found to reach 1,480 U/g, with enzyme activity recovery of 74.5%. Compared to the free lipase, thermal stability of the immobilized lipase was greatly improved. The reusability study indicated that the immobilized lipase retained 76.6% of its initial activity after being recycled five times. A preliminary study indicated that the prepared immobilized lipase can effectively enrich the polyunsaturated fatty acid in fish oil (increasing from 45.1 to 67.7%), of which the combined docosahexaenoic acid and eicosapentaenoic acid contents increased from 16.3 to 27.1%. Practical applications To overcome the drawbacks of using free lipase, an effective method was developed by immobilization of lipase onto N-succinyl-chitosan beads using EDC/NHS as the activating agent. The immobilized lipase prepared by this method may find application in the enrichment of polyunsaturated fatty acids of fish oil.