Abstract
A dual immobilized enzyme system composed of immobilized β-amylase [EC 3.2.1.2] and pullulanase [EC 3.2.1.41] was studied for the continuous production of maltose. Porous chitosan beads were selected from among many commercial carriers as the best carrier to immobilize β-amylase.
The properties of the immobilized enzyme were examined and compared with those of the native enzyme. The optimum pH of the immobilized β-amylase shifted slightly to the alkaline side and the pII stability was improved. The optimum temperature of the immobilized enzyme increased by about 5°C and the thermostability of the enzyme did not change compared to the native enzyme.
Using a dual immobilized enzyme system composed of immobilized β-amylase and pullulanase, the effects of operating conditions on the maltose production reaction were examined. To obtain a maltose content of higher than 75% (w/w), it was necessary to operate at a space velocity of below 0.6hr-1 with a substrate concentration of below 25% (w/w) under the optimum reaction conditions. Also, the dual enzyme system proved to be effective in increasing the maltose content in the product.
