Impact of processing on the phenolic profiles of small millets: evaluation of their antioxidant and enzyme inhibitory properties associated with hyperglycemia

Food Chem. 2015 Feb 15;169:455-63. doi: 10.1016/j.foodchem.2014.08.010. Epub 2014 Aug 13.

Abstract

The effects of germination, steaming and microwave treatments of whole grain millets (barnyard, foxtail and proso) on their phenolic composition, antioxidant activities and inhibitory properties against α-amylase and α-glucosidase were investigated. Compositional analysis of phenolics by HPLC revealed that vanillic and ferulic acids were the principal phenolic acids and kaempferol was the predominant flavonoid found in raw millets. Different processing treatments brought about relevant changes in the composition and content of certain phenolic acids and flavonoids in processed millets. Phenolic extracts of raw and processed millets exhibited multiple antioxidant activities and are also potent inhibitors of α-amylase and α-glucosidase. In general, germinated millets showed highest phenolic content as well as superior antioxidant and enzyme inhibitory activities. These results suggest that germinated millet grains are potential source of phenolic antioxidants and also great sources of strong natural inhibitors for α-amylase and α-glucosidase.

Keywords: Antioxidant activity; Flavonoids; Millets; Phenolic acids; Phenolic compounds; α-Amylase inhibition; α-Glucosidase inhibition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / analysis*
  • Antioxidants / chemistry
  • Chelating Agents / chemistry
  • Chromatography, High Pressure Liquid
  • Coumaric Acids / chemistry
  • Enzyme Inhibitors / analysis*
  • Enzyme Inhibitors / chemistry
  • Flavonoids / analysis
  • Flavonoids / chemistry
  • Free Radical Scavengers / chemistry
  • Germination / drug effects
  • Humans
  • Hydrogen Peroxide / chemistry
  • Hyperglycemia / enzymology*
  • Ions / chemistry
  • Kaempferols / chemistry
  • Oxidation-Reduction
  • Panicum / chemistry*
  • Phenols / analysis*
  • Plant Extracts / analysis
  • Plant Extracts / chemistry
  • Solvents / chemistry
  • Vanillic Acid / chemistry
  • alpha-Amylases / metabolism
  • alpha-Glucosidases / metabolism

Substances

  • Antioxidants
  • Chelating Agents
  • Coumaric Acids
  • Enzyme Inhibitors
  • Flavonoids
  • Free Radical Scavengers
  • Ions
  • Kaempferols
  • Phenols
  • Plant Extracts
  • Solvents
  • kaempferol
  • ferulic acid
  • Hydrogen Peroxide
  • alpha-Amylases
  • alpha-Glucosidases
  • Vanillic Acid