In the first of two enzymatic steps that produce high-glucose syrup as an intermediate to high-fructose syrup and other products, bacterial α-amylase is employed at pH 6–7 and about 105°C to hydrolyze starch purified by wet milling to roughly DE (dextrose equivalent) 10, DE being the percent of reducing end-groups in the aqueous sugar mixture relative to those in pure glucose of the same concentration. This indicates that the average maltooligosaccharide produced has a DP (degree of polymerization) of 10, although the mixture has a very wide DP range. DE 30 or more can be attained if the reaction proceeds to completion, but DE 10 is chosen to minimize the probability of pseudo-crystallization at lower DEs and the extent of alkaline-catalyzed isomerization of the reducing-end glucosyl residue at higher DEs.In the second step, at pH 4.3–4.5 and roughly 60°C, fungal glucoamylase and a small amount of pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41), the latter used to rapidly hydrolyze the α-1,6 bonds from the original starch feed, convert the maltooligosaccharide mixture to approximately 96% glucose (dry basis). The remainder is composed of byproducts from α-amylase hydrolysis plus mainly isomaltose [α-glucopyranosyl-(1,6)-glucose] and isomaltotriose from the glucoamylase-catalyzed condensation of glucose.