Phenolic acids, anthocyanins, proanthocyanidins, antioxidant activity, minerals and their correlations in non-pigmented, red, and black rice

Food Chem. 2018 Jan 15:239:733-741. doi: 10.1016/j.foodchem.2017.07.009. Epub 2017 Jul 3.

Abstract

Soluble-free, soluble-conjugated, insoluble-bound phenolics and antioxidant activity, flavonoid (TFC), proanthocyanidins (TPAC), anthocyanins and minerals of fifteen whole rice grains with different colors were investigated. Soluble-free protocatechuic and vanillic acids were only quantified in black rice, which had the most quantities. Non-pigmented rice had no detectable conjugated protocatechuic and 2,5-dihydroxybenzoic acids both of which were found in black and red rice, respectively. The main bound phenolic acids were ferulic and p-coumaric, as well as 2,5-dihydroxybenzoic in red rice and protocatechuic and vanillic acids in black rice. Soluble-conjugated phenolics, TFC, and anthocyanins were negatively correlated with L, b, C and H° values. TPAC was positively correlated with a (P<0.01). Protocatechuic, vanillic, syringic and ferulic acids were associated with TPC and antioxidant activity in the soluble-conjugated fraction while protocatechuic and ferulic acid were correlated with those in the insoluble-bound fraction. Principal component analysis divided samples into non-pigmented, red and black rice groups.

Keywords: Anthocyanins; Antioxidant activity; Minerals; Phenolic acids; Principal component analysis; Proanthocyanidins; Whole rice grain.

MeSH terms

  • Anthocyanins
  • Antioxidants
  • Hydroxybenzoates
  • Minerals
  • Oryza*
  • Phenols
  • Plant Extracts
  • Proanthocyanidins

Substances

  • Anthocyanins
  • Antioxidants
  • Hydroxybenzoates
  • Minerals
  • Phenols
  • Plant Extracts
  • Proanthocyanidins
  • phenolic acid