Effects of sorghum (Sorghum bicolor (L.) Moench) tannins on α-amylase activity and in vitro digestibility of starch in raw and processed flours

Nyambe L. Mkandawire, Rhett C. Kaufman, Scott R. Bean, Curtis L. Weller, David S. Jackson, Devin J. Rose

Research output: Contribution to journalArticle

52 Scopus citations

Abstract

The purpose of this study was to investigate the effects of tannins on starch digestion in tannin-containing sorghum extracts and wholegrain flours from 12 sorghum varieties. Extracts reduced amylase activity in a tannin concentration-dependent manner when the extract was mixed with the enzyme before substrate (amylopectin) addition, with higher molecular weight tannins showing greater reduction. Conversely, when the extract and substrate were combined before enzyme addition an enhancement in amylase activity was experienced. In uncooked, cooked, and cooked and stored wholegrain sorghum flours, rapidly digestible, slowly digestible, and resistant starches were not correlated with tannin content or molecular weight distribution. Resistant starch increased from 6.5% to 22-26% when tannins were added to starch up to 50% (starch weight). Tannin extracts both reduced and enhanced amylase activity depending on conditions, and, while these trends were clear in extracts, the effects on starch digestion in wholegrain flours was more complex.

Original languageEnglish (US)
Pages (from-to)4448-4454
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Volume61
Issue number18
DOIs
StatePublished - May 8 2013

Keywords

  • Englyst test
  • digestion
  • polyphenols
  • processing
  • resistant starch
  • slowly digestible starch

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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