Immobilization of Sucrose Isomerase by Adsorption and Crosslinking Method for the Synthesis of Isomaltulose

Abstract:

Sucrose isomerase from the recombinant strain was immobilized on chitosan cross-linked with glutaral-dehyde. The effects of chitosan concentration，glutaraldehyde content，enzyme concentration，crosslinking time were investigated using the immobilized enzyme activity recovery rate as an index.，and the effects of temperature，pH，enzyme dosage，reaction time and substrate concentration on the production of isomaltulose by immobilized sucrose isomerase were also investigated. The immobilization efficiency reached up to 70.3% under the optimal condition of immobilization achieved with 3.0% of the chitosan，0.75% glutaraldehyde content，50 U/g chitosan beads and 16 h. The optimum conditions of the synthesis of isomaltulosewere as follows：reaction temperature 30 ℃，initial pH 4.5，enzyme concentration 15 U/g sucrose，conversation time 12 h，initial sucrose concentration 600 g/L. When the reaction was performed under this specified conditions，the isomaltulose yield reached the maximum of 87.8%. The yield ratio was still up to 87.52% after 16 times of continuous conversion and it shows a good operational stability and a high productivity of isomaltulose.