A E Staley Manufacturing Company

Thomas L Hurst

Kenneth B Moser

James A Lotzgesell

Iron ions may be effectively used as a metal activator or co-metal activator in glucose isomerization when used in conjunction with thiol activators. The thiol activators are characterized as being able to cleave disulfide linkages and include reducing reagents such as water-soluble SO.sub.3.sup.= producing metal salts, ascorbic acid, thiocyanates, thioglycollates, etc. The thiol activator-iron ion activating system is especially effective when used in conjunction with at least one other metal ion activator such as magnesium, manganese or cobalt ions. Effective enzymatic glucose isomerization, without using cobalt ions, is achievable by a magnesium-iron-thiol activator-isomerase system.

Glucose isomerization with iron ion-thiol activator ion-glucose

The isomerase activity of a dry isomerase preparation (e.g., glucose isomerase) is enhanced by initially pretreating the isomerase in an aqueous solution which contains an activating amount of a metal ion activator and/or a thiol generating reducing agent and/or a monosaccharide which the isomerase is capable of isomerizing. Pretreatment temperature and time periods are most suitably conducted in such a manner so as to minimize isomerase deactivation. The pretreatment increases total isomerase activity and thereby renders it more effective for use in an isomerization process (e.g., glucose isomerization).

Dry isomerase activation

An improved method for thinning starch in the granular state employing hydrogen peroxide and metal ion catalysts in an aqueous suspension, free of buffer additions. The thinning action proceeds in acid pH to the desired viscosity level, and is stopped by the addition of sodium metabisulfite, or other reducing agent to remove residual hydrogen peroxide. The aqueous suspension is then neutralized, and the usual purifying and drying steps are effected on the granular product.

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Decatur, IL, United States of America

Thomas L Hurst