Improved Co-immobilizate of Glucoamylase and Glucose Isomerase : Continuous Production of Fructose Syrup Directly from Liquefied Starch

The co-immobilizate of glucoamylase (GA) and mycelia-bound glucose isomerase (GI), which was previously reported by Takeda and Hizukuri (Denpun Kagaku, 36, 169-176 (1989)), was improved as to the productivity of the fructose syrup (isosyrup). The co-immobilizate was prepared by linking a partially purified GA to the GI at the high GA/GI ratio of 1/1(w/w). The resulting co-immobilizate continuously produced the isosyrup comprising fructose, glucose, and oligosaccharides of 43. 3, 54. 1, and 2.6%, respectively, directly from the 30% liquefied starch with a d. p. of 3.8 under the optimum conditions : 55°C, pH 7. 3, and the space velocity of 0.3 hr-1. The results indicated that the co-immobilizate produced the isosyrup having a lower amount of oligosaccharides at a higher rate (about threefolds) than the previous co-immobilizate.