Abstract
The continuous reaction ot cyclodextrin (CD) formation From potato starch by immobilized cyclodextrin glucanotransferase (CGT-ase) on ion exchange resins is reported in this paper. As suitable carriers of the immobilized CGT-ase, high-porous type resins were selected, one was IRA-93 as a weakly basic resin, the other was HN-11-22 as a strongly basic resin (both are products of Organo Co.). Experiments were done using plug flow column.
At first, relationship between amount of immobilized enzyme on ion exchange resin and CD formation ratios for varied flow rates (SV) was studied. It was clear that CD formation ratio is greatly affected by the relationship between the amount of enzyme immobilized and the flow rate of substrate. when the amount of the immobilized enzyme is too much for the substrate solution's flow rate, the CD formation ratio is decreased. It is presumably due to other reactions of CGT-ase except the cyclization. The CD formation can be controlled to some extent by increasing or decreasing the SV value, i.e. flow rate of substrate according to the amount of immobilized enzyme.
In the second, the 30 days continuous running experiment was undertaken using immobilized CGT-ase on IRA-93 ion exchange resin by passing the liquefied potato starch solution through the resin column plug flow reactor. As the result, the activity of immobilized CGT-ase decreased with a half-life period of about 21 days. By decreasing the flow rate of the substrate solution stepwise starting with the initial SV value of 0.5 down to the final SV value of 0.26, the continuous running could be performed over a period of 21 days. The results here obtained led to a conclusion that an industrially practicable process could be established possibly by the cycling use of 3 to 4 columns in connection each filled with the immobilized CGT-ase.
