For the economical production of ethanol from starch it is necessary to run the process continuously from the raw material starch to the end product ethanol. One of the difficulties is the production of glucose from starch employing α-amylase for liquefaction and glucoamylase for saccharification which are currently done batchwise. This process is inefficient with respect to enzyme utilization since the enzyme is not recovered and reused. The overall objective of this work is to develop the method of enzyme immobilization for saccharification.
Starch saccharification by immobilized glucoamylase was chosen because of its economic significance. The catalytic activity of immobilized glucoamylase in a packed-bed reactor and a continuous stirred tank reactor have been compared. The differential reactor was used for the determination of the kinetic parameters. Rapid production of high concentration of glucose from liquefied starchy material through the continuous liquefaction and saccharification using settling chamber have been stuied. Factors affecting reactor performance, such as enzyme concentration, substrate concentration, and reactor temperature on the glucose concentration in the product stream have been stuied. The optimal temperature and pH of the liquefaction were 90°C and 6.0, respectively. In saccharification, the optimal temperature and pH were 60°C and 4.8, respectively. In the case of saccharification in batch reactor with a naked barley concentration of 15% and glucoamylase concentration of 0.13% (v/w), 85% hydrolysis was obtained after 18h. The immobilized glucoamylase with chitin in a packed bed reactor gave the saccharification yield of 20% with the dextrin concentration of 10%. In continuous liquefaction and saccharification, the glucose yield was 17% for the liquefied starch with naked barley concentration of 5%.
