HPLC-PDA-ESI-MS Identification of Polyphenolic Phytochemicals in Different Market Classes of Common Beans (Phaseolus vulgaris L.)
V. Nyau *
Department of Food Science and Technology, University of Zambia, Lusaka, Zambia.
S. Prakash
Department of Chemistry, University of Zambia, Lusaka, Zambia.
J. Rodrigues
Department of Molecular and Cell Biology, University of Cape Town, 7701 Rondebosch, South Africa.
J. Farrant
Department of Molecular and Cell Biology, University of Cape Town, 7701 Rondebosch, South Africa.
*Author to whom correspondence should be addressed.
Abstract
Aim: The aim of the study was to screen the market classes of common beans popularly grown in Zambia for their polyphenolic phytochemical profiles.
Methodology: Three market classes of common bean (red, grey mottled and brown) were investigated for their polyphenolic phytochemical profiles using the High Performance Liquid Chromatography-Photo Diode Array-Electrospray Ionization-Mass Spectrometry (HPLC-PDA-ESI-MS).
Results: Various phenolic compounds were identified in the Zambian market classes of common beans. Quinic acid, a syringic acid derivative, ferulic acid derivatives, medioresinol, p-coumaric acid, catechin, gallic acid and ferulic acid were identified in all the market classes investigated. However, the isomers of ferulic acid derivatives observed were 4 in red, 3 in brown and 1 in grey mottled beans. Epicatechin was only identified in the red and grey mottled beans. A compound with the molecular ion at m/z 567, tentatively identified as a flavonone derivative was only observed in red beans. Catechin glucoside was only identified in grey mottled and brown beans. Compounds tentatively identified as kaempferol glucoside and carnosol were only observed in brown beans and not in the other market classes.
Conclusion: The study has shown that the market classes of common beans investigated contain various polyphenolic compounds that may be useful as nutraceuticals. The study assumes that the diversity in the phenolic phytochemical profile is an excellent opportunity for genetic improvement in the nutraceutical attributes of these common bean market classes by crop breeders.
Keywords: Common beans, phenolics, phytochemicals, nutraceuticals