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Formation of slowly digestible, amylose–lipid complexes in extruded wholegrain pearl millet flour

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  • Pablo Cesar Torres-Aguilar, Purdue University
  • ,
  • Anna Marie Rose Hayes, University of Southern California
  • ,
  • Ximena Yepez, Escuela Superior Politecnica del Litoral ESPOL
  • ,
  • Mario Martinez Martinez
  • Bruce Rankin Hamaker, Purdue University

Pearl millet (Pennisetum glaucum) is one of the most promising but underutilised crops in sub-Saharan Africa. Here, we evaluated the use of extrusion cooking of wholegrain pearl millet related to the formation of amylose–lipid complexes (ALCs) and their potential effect on slowing starch digestion. Thermal properties (differential scanning calorimetry), fatty acid (FA) profiles (derivatization followed by gas chromatography), ALC dissociation (hexane extraction followed by derivatization and gas chromatography) and in vitro starch digestibility (α-amylase digestion assay) were determined for wholegrain and decorticated pearl millet flours in both native and extruded states. Extrusion cooking melted stable type II complexes naturally present in native flours into type I complexes characterised by a melting endotherm in the 82–112 °C range. Extrusion caused the formation of ALC-containing mono- and polyunsaturated fatty acids, which were not found in native flours. Extruded instant flours exhibited a moderated release of reducing sugars compared to cooked native samples and the effect was more pronounced in the wholegrain flour. This effect was lost when the extruded samples were cooked, though instant flours would retain the effect if rehydrated with warm rather than boiling hot water. When extruded, wholegrain millet had some enhancement of a slow digestion effect.

Original languageEnglish
JournalInternational Journal of Food Science and Technology
Pages (from-to)1336-1345
Number of pages10
Publication statusPublished - Mar 2023

Bibliographical note

Funding Information:
This work was made possible by the support of the American People provided to the Feed the Future Innovation Lab for Food Processing and Post‐harvest Handling Innovation through the United States Agency for International Development (USAID) under Cooperative Agreement No. AID‐OAA‐A‐13‐00047. The contents are the sole responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government.

Publisher Copyright:
© 2023 The Authors. International Journal of Food Science & Technology published by John Wiley & Sons Ltd on behalf of Institute of Food, Science and Technology (IFSTTF).

    Research areas

  • Amylose–lipid complex, extrusion, In vitro digestion, pearl millet, slow digestion

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