Simultaneous saccharification and isomerization by immobilized glucoamylase and glucose isomerase

Glucoamylase (GA) and glucose isomerase (GI), which are often used in industry to produce high‐fructose corn syrup, were immobilized on porous anilinosulphonic polystyrene beads and porous triethanolamine methyl polystyrene beads, respectively. The effects of the amounts of charged groups, the porosity of the carrier and the buffer concentration on the pH profile of immobilized glucose isomerase (IGI) were studied. The apparent pH optimum of the IGI shifted from pH 8.5 to pH 7.3, hence it is possible to carry out simultaneous saccharification and isomerization in a tubular reactor using immobilized glucoamylase (IGA) and IGI. This process is very difficult to accomplish using soluble GA and GI because of the large difference in the pH optima of the two enzymes.