Number of branch points in alpha-limit dextrins impact glucose generation rates by mammalian mucosal alpha-glucosidases

Abstract

alpha-Amylase first hydrolyzes starch structures to linear maltooligosaccharides and branched alpha-limit dextrins, then complete hydrolysis to glucose takes place through the mucosal alpha-glucosidases. In this study, we hydrolyzed waxy corn starch (WCS) by human pancreatic alpha-amylase to determine the digestion and structural properties of different size fractions of the branched alpha-limit dextrins. The alpha-amylolyzed WCS was separated by size exclusion chromatography, and the analyzed chromatograms showed four main hydrolyzate fractions. The first three eluted peaks (regions I-III) corresponded to branched alpha-limit dextrins, while region IV was the linear maltooligosaccharides. Based on the chromatographic and NMR analyses of the individual peaks, Region I, II, and III had multiple (>2), two, and one alpha-1,6 linkages, respectively, and region I was the most slowly hydrolyzed to glucose by mucosal alpha-glucosidases (hydrolysis rate: Region I < II < III < IV). This study shows the possibility of producing slowly digestible oligosaccharides that may decrease postprandial glycemic response and control glucose delivery to the body, to address metabolic syndrome-associated diseases. (C) 2016 Published by Elsevier Ltd.