Pretreatment of glucose feedstock with reducing agents

DETAILED DESCRIPTION What is claimed is: 1.
In a method of converting glucose to fructose using an immobilized glucose isomerase system, the improvement wherein a feedstock containing glucose and minor amounts of isomerase poisons, prior to contacting with the immobilized glucose isomerase system, is treated with a water soluble and water stable metal hydride at a pH from about 7 to about 9 at a temperature from about 10.
degree.
to about 80.
degree.
C.
for a time and in an amount effective to increase the productivity of said immobilized glucose isomerase system above that productivity occurring when the enzymatic isomerization is carried out without the presence of said metal hydride, the treatment being for a time sufficient to destroy said poisons.
2.
The process of claim 1 wherein the hydride is selected from the group consisting of sodium borohydride, and cyano and alkoxy-substituted sodium borohydrides.
3.
The process of claim 2 where the hydride is sodium borohydride.
4.
The process of claim 2 where the hydride is sodium cyanoborohydride.
5.
The process of claim 1 where the pH is between about 8 and about 9.
6.
The process of claim 1 where the effective amount is between about 20 and about 500 parts per million.
7.
The process of claim 6 where the amount is between 40 and about 200 parts per million.
8.
The process of claim 7 where the amount is from about 50 to about 150 parts per million.




Description:
BACKGROUND OF THE INVENTION Fructose, or grape sugar, has been used as a sugar substitute in many applications.
Increasing sugar prices spur increased fructose usage, and current fructose production is at an all-time peak.
The largest commercial source of fructose is glucose, an end product of starch hydrolysis, which is isomerized to fructose by enzymatic methods using glucose isomerase.
Because the high enzyme cost dictates its reuse, the isomerization is not done homogeneously where recovery of enzyme would be difficult and costly, but instead is performed heterogeneously using glucose isomerase immobilized in some manner