Novel maltulose-containing syrups and process for making the same

Abstract

Sweet, non-crystallizing (at concentrations of 75% solids or above) syrups are prepared having the following saccharide composition: dextrose, from 20% to 40% levulose, from 20% to 40%; maltulose, from 10% to 60%; total ketose composition (principally levulose and maltulose), 40% to 80% (percentages by weight dry basis). Optionally, the syrups may contain up to 25% maltose and/or up to 20% higher saccharides (i.e. having degrees of polymerization of greater than 2). The syrups are prepared by first subjecting a starch hydrolyzate, containing at least 40% maltose and not more than 5% dextrose, to an alkaline isomerization treatment to isomerize a portion of the maltose to maltulose, the isomerization being conducted until the resulting hydrolyzate contains between 10% and 60% maltulose. The resulting product is then treated with glucoamylase to saccharify at least a portion of the remaining maltose (as well as higher saccharides, if present) to dextrose. That hydrolyzate is finally subjected to an isomerization reaction to isomerize up to 50% of the dextrose to levulose.

What is claimed is: 
     
       1. A process for preparing a sweet syrup composition comprising the steps of: a. first subjecting a maltose-containing starch hydrolyzate, containing at least 40% maltose and not more than 5% dextrose, to an alkaline isomerization treatment to isomerize a portion of the maltose to maltulose, said isomerization being conducted so as to provide from 10% to 60% maltulose, by weight dry basis, in the hydrolyzate,   b. then subjecting the hydrolyzate to the action of glucoamylase under conditions which will cause the glucoamylase to saccharify the maltose and the saccharides having a degree of polymerization greater than 2 present in the hydrolyzate, without saccharifying the maltulose, the saccharification reaction being conducted until the hydrolyzate contains from 0% to 25% maltose plus at least 40% dextrose, and   c. subjecting the resulting hydrolyzate to an isomerization reaction to isomerize up to 50% of the dextrose to levulose.   
     
     
       2. The process of claim 1, wherein the maltose-containing starch hydrolyzate of step a. contains at least 60% maltose. 
     
     
       3. The process of claims 1 or 2 wherein the isomerization of the dextrose to levulose is performed with glucose isomerase. 
     
     
       4. The process of claims 1 or 2 wherein the glucoamylase treatment of step b. is conducted at a pH of between 4.0 and 6.0, and a temperature of between 45° C. and 75° C., using between 30 and 250 activity units of the enzyme, the reaction being terminated when the substrate contains at least 40% dextrose and between 0% and 25% maltose. 
     
     
       5. The process of claim 4 wherein the pH of the treatment is 4.5 and between 50 and 150 activity units of the enzyme are used.