Lipase Catalyzed Synthesis Of Sucrose-6-Acetate

Sucralose is a kind of sweetener which has high sweetness and noncalorie,and has good physical functioning.Sucrose-6-acetate is a key intermediate in synthesis of sucralose.Enzymatic synthesis of sucrose-6-acetate has many advantages.Such as: good regional selectivity,mild reaction conditions,friendly to environment.This paper used Immobilized Aspergillus niger lipase and Thermomyces lanuginosus immobilization lipase(TLIM)as catalyst to catalytic synthesis of sucrose-6-acetate.This paper optimized the synthesis conditions to increase the rate of esterification and 6-position selectivity.And we used surfactant coating techniques or molecular imprinting technologies to improve the catalytic activity of enzyme.This paper obtained surfactant coated Thermomyces lanuginosus immobilization lipase(TLIM)and immobilized imprinting Aspergillus niger lipase which both have better catalytic activity.(1)This paper screened immobilized Aspergillus niger lipase as catalyst,determined the appropriate reaction system and optimized synthesis conditions of sucrose-6-acetate.We found that the mixed organic phase(tertamyl alcohol:dimethyl sulfoxide=5:1)was the most suitable reaction system.Under optimum synthesis conditions,we used immobilized Aspergillus niger lipase as catalyst to catalytic synthesis of sucrose-6-acetate,the esterification rate up to 72.6%,6-position selectivity is 83.6%;we used TLIM as catalyst to catalytic synthesis of sucrose-6-acetate,the esterification rate up to 80.1%,6-position selectivity is 87.4%.We also found amplification reaction system to 100 mL,the synthesis process was stable and the results were consistent with the results of a small trial.(2)This paper combined surfactant coating technology and enzyme immobilization technology together.We used surfactant to coat TLIM and immobilized Aspergillus niger lipase and optimized the coating conditions.We found that the catalytic activity of coated TLIM were enhanced,but the catalytic activity of coated immobilized Aspergillus niger lipase were decreased.Using span 85 to coat TLIM,the catalytic activity could be improved most and was up to 0.5 times than non-coated TLIM.(3)This paper combined molecular imprinting techniques and enzyme immobilization technology together.We used imprinting molecular to imprint Aspergillus niger lipase first,then immobilized it,and explored imprinting conditions.Under optimum imprinting conditions,we obtained imprinting enzyme and used it to catalytic synthesis of sucrose-6-acetate,the esterification rate up to 82.4%,6-position selectivity is 82.5%.The catalytic activity of imprinting Aspergillus niger lipase was up to 0.2 times than immobilized Aspergillus niger lipase.The operating stability of imprinting Aspergillus niger lipase and TLIM was basically consistent in mixed organic phase.