Skip to main content
ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #300045

Title: Enzyme-synthesized highly branched maltodextrins have slow glucose generation at the mucosal alpha-glucosidase level and are slowly digestible "in vivo"

Author
item LEE, BYUNG-HOO - Purdue University
item YAN, LIKE - Purdue University
item PHILLIPS, ROBERT - Purdue University
item REUHS, BRADLEY - Purdue University
item JONES, KYRA - University Of Waterloo
item ROSE, DAVID - University Of Waterloo
item NICHOLS, BUFORD - Children'S Nutrition Research Center (CNRC)
item QUEZADA-CALVILLO, ROBERTO - Children'S Nutrition Research Center (CNRC)
item YOO, SANG-HO - Sejong University
item HAMAKER, BRUCE - Purdue University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2013
Publication Date: 4/2/2013
Citation: Lee, B., Yan, L., Phillips, R.J., Reuhs, B.L., Jones, K., Rose, D.R., Nichols, B.L., Quezada-Calvillo, R., Yoo, S., Hamaker, B.R. 2013. Enzyme-synthesized highly branched maltodextrins have slow glucose generation at the mucosal alpha-glucosidase level and are slowly digestible "in vivo". PLoS One. 8(4):e59745.

Interpretive Summary: Foods containing slowly digestible glucose chains in starches cause consumers to have a slowed rise in blood glucose after a meal. This is due to a reduced rate of intestinal glucose release. This may be very important in diets for individuals having diabetes or pre-diabetes. In this study waxy corn starch was experimentally modified using enzymes to increase extent of branching and shorten the glucose chain structure. The digestibility of the modified starch products was investigated in test-tubes using four small intestinal mucosal enzymes, Maltase-glucoamylase (MGAM) and Sucrase-isomaltase (SI). This is the first report showing that digestion rates by all of these mucosal intestinal enzymes is limited by increased numbers of branches in food starches. These highly branched starches show promise as a crop-based food product to control blood glucose levels after a meal, and treatments to slow digestion of glucose for children having diabetes or pre-diabetes.

Technical Abstract: For digestion of starch in humans, alpha-amylase first hydrolyzes starch molecules to produce alpha-limit dextrins, followed by complete hydrolysis to glucose by the mucosal alpha-glucosidases in the small intestine. It is known that alpha-1,6 linkages in starch are hydrolyzed at a lower rate than are alpha-1,4 linkages. Here, to create designed slowly digestible carbohydrates, the structure of waxy corn starch (WCS) was modified using a known branching enzyme alone (BE) and an in combination with beta-amylase (BA) to increase further the alpha-1,6 branching ratio. The digestibility of the enzymatically synthesized products was investigated using alpha-amylase and four recombinant mammalian mucosal alpha-glucosidases. Enzyme-modified products (BE-WCS and BEBA-WCS) had increased percentage of alpha-1,6 linkages (WCS: 5.3%, BE-WCS: 7.1%, and BEBA-WCS: 12.9%), decreased weight-average molecular weight (WCS: 1.73 x 10(8) Da, BE-WCS: 2.76 x 10(5) Da, and BEBA-WCS 1.62 x 10(5) Da), and changes in linear chain distributions (WCS: 21.6, BE-WCS: 16.9, BEBA-WCS: 12.2 DPw). Hydrolysis by human pancreatic alpha-amylase resulted in an increase in the amount of branched alpha-limit dextrin from 26.8% (WCS) to 56.8% (BEBA-WCS). The alpha-amylolyzed samples were hydrolyzed by the individual alpha-glucosidases (100 U) and glucogenesis decreased with all as the branching ratio increased. This is the first report showing that hydrolysis rate of the mammalian mucosal alpha-glucosidases is limited by the amount of branched alpha-limit dextrin. When enzyme-treated materials were gavaged to rats, the level of postprandial blood glucose at 60 min from BEBA-WCS was significantly higher than for WCS or BE-WCS. Thus, highly branched glucan structures modified by BE and BA had a comparably slow digesting property both in vitro and in vivo. Such highly branched alpha-glucans show promise as a food ingredient to control postprandial glucose levels and to attain extended glucose release.