Glucose isomerase immobilized

P-amylase, and debranching enzymes. Conversion of D-glucose to D-fmctose is mediated by glucose isomerase, mosdy in its immobilized form in columns. Enzymic degradation of starch to symps has been well reviewed (116—118), and enzymic isomerization, especially by immobilized glucose isomerase, has been fiiUy described (119) (see Syrups). 

Manufacture. HFS containing 42% fmctose is produced commercially by column isomerization of clarified and refined dextrose hydrolyzate using an immobilized glucose isomerase. Enriched symp containing 90% fmctose is prepared by chromatographic separation and blended with 42% HES... 

Two types of immobilization are used for immobilizing glucose isomerase. The intracellular enzyme is either immobilized within the bacterial cells to produce a whole-ceU product, or the enzyme is released from the cells, recovered, and immobilized onto an inert carrier. An example of the whole-ceU process is one in which cells are dismpted by homogenization, cross-linked with glutaraldehyde, flocculated using a cationic flocculent, and extmded (42). 

Table 2. Typical Operating Parameters for Immobilized Glucose Isomerase and Penicillin V Acylase...

Enzyme treatment and processing costs are relatively high, for instance lactase costs are estimated at 200 /ton of product, as compared with immobilized glucose isomerase and inverlase treatments that cost 2-3 /ton product and 15-30 /ton of product, respectively. 

Table 6.1 Examples of commercial immobilized glucose isomerases.

When immobilized glucose isomerase was introduced in the early seventies, it was believed, that other industrial applications of immobihzed enzymes would soon be found, but this turned out not to be trae. The main limitation to the use of immobilized enzymes is that the substrate has to be soluble and highly purified in order to avoid clogging of the enzyme bed. In the case of glucose isomerase the cost of purifying the syrup (carbon treatment, ion exchange) before the fixed bed isomerase reactors is substantially higher than the enzyme costs. 

Pedersen, S. (1993) Industrial aspects of immobilized glucose isomerase. Industrial Application of immobilized biocatalysts, edited by A.Tanaka, T.Tosa and T.Kobayashi. New York Marcel Dekker, Inc. 

J. A. Roels and R. van Tilberg, Temperature dependence of the stability and the activity of immobilized glucose isomerase,... 

The conversion step to high-fructose syrup takes place in a reactor containing immobilized glucose isomerase. Although nonenzymic processes to isomerize glucose to fructose have been developed,11 these processes result in undesirable by-products of ash, color, and flavor, and other faults. 

FIGURE 32 Column Assembly for Assay of Immobilized Glucose Isomerase. 

Many examples of the use of immobilized enzymes in food processing have been reported. One of the most important of these is the use of immobilized glucose isomerase obtained from Streptomyces for the production of high-fructose com syrup (Mermel-stein 1975). In this process, the enzyme is bound to an insoluble carrier such as diethyl amino ethyl cellulose or a slurry of the fixed... 

Immobilized glucose isomerase is used as a catalyst in producing fructose from glucose in a fixed-bed reactor (water is the solvent). For the system shown in Fig. E2.26a, what percent conversion of glucose results on one pass through the reactor when the exit stream/recycle ratio in moles is equal to 8.33 The reaction is... 

Immobilized glucose isomerase for the production of high-fructose corn syrup... 

---