Characterization and estimation of proanthocyanidins and other phenolics in coffee pulp (Coffea arabica) by thiolysis-high-performance liquid chromatography.
Fresh and 3-day-old coffee pulp of the Arabica variety were analyzed for polyphenol composition followed by characterization by two different methods. The first method consisted in subjecting coffee pulp powder to direct thiolysis. For the second method, coffee pulp was subjected to successive solvent extractions, followed by thiolysis. Quantification of phenolic compounds was then achieved by high-performance liquid chromatography (HPLC) analysis of thiolysis products. Four major classes of polyphenols were identified: flavan-3-ols (monomers and procyanidins), hydroxycinnamic acids, flavonols, and anthocyanidins. Differences in concentration of procyanidins were observed between fresh and 3-day-old coffee pulp. Constitutive units were mainly epicatechin, representing more than 90% of the proanthocyanidin units, with average degrees of polymerization in the range of 3.8-9.1. Monomer to hexamer units of flavan-3-ols from fresh coffee pulp were separated by normal-phase HPLC. Molecular size of oligomeric proanthocyanidins was obtained by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results obtained confirm the presence of oligomers of the flavan-3-ol (-)-epicatechin.
Institut de Recherche pour le Développement, Case 925, 163 Avenue de Luminy, Cedex 09, F-13288, Marseille, France.
Maria Ascencion
MA
Ramirez-Coronel
Nathalie
N
Marnet
V S Kumar
VS
Kolli
Sevastianos
S
Roussos
Sylvain
S
Guyot
Christopher
C
Augur
D002851:Chromatography, High Pressure Liquid; D040503:Coffea / Q000737:chemistry*; D003373:Coumaric Acids / Q000032:analysis; D044948:Flavonols / Q000032:analysis; D013058:Mass Spectrometry; D010636:Phenols / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry; D044945:Proanthocyanidins / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D003373:Coumaric Acids; D044948:Flavonols; D010636:Phenols; D010936:Plant Extracts; D044945:Proanthocyanidins