Glucose Release of Water-Soluble Starch-Related α-Glucans by Pancreatin and Amyloglucosidase Is Affected by the Abundance of α-1,6-Glucosidic Linkages

This study tested the hypothesis that an increased branch density (i.e., the percentage of α-1,6-glucosidic linkage) in water-soluble, starch-related α-glucans leads to reduced glucose release by pancreatin and amyloglucosidase. Malto-oligosaccharides and phytoglycogens were structurally analyzed and compared for their susceptibility to the enzymes. Malto-oligosaccharides were prepared by subjecting starch to α-amylase and β-amylase followed by ultrafiltration to enrich α-1,6-glucosidic linkages. The branch density of the oligosaccharide products reached up to 17%, determined by 1H NMR. Phytoglycogens were extracted from six sweet corn lines, and analysis showed similar chain length distributions and a branch density range from 8.8 to 9.5%, as compared with 4.6% for normal corn starch and 5.7% for waxy corn starch. The digestion behavior of these α-glucans was correlated to branch density: Highly branched malto-oligosaccharides had much reduced glucose release as compared with starch, whereas the reductio...