Fractionation of grape tannins and analysis by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.
Polymeric tannins, extracted from grape berries (Gamay variety), were fractionated according to their mean degree of polymerisation (mDP) on a styrene-divinylbenzene phase eluted with a gradient of methanol:chloroform. Increasing the percentage of methanol led to the solubilisation of higher molecular weight tannins. The mean mDP of each collected fraction was determined by acid-catalysed degradation in the presence of a nucleophilic reagent. The fractionation method produced a linear gradient of mDP varying between 1.84 and 19.34. The fractions were partially characterised by matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). The spectra showed a complex mixture of proanthocyanidins and galloylated proanthocyanidins up to 4000 amu.
Perret
Camille
C
Institut de Chimie, Université de Neuchâtel, Av. de Bellevaux 51, CH-2000 Neuchâtel, Switzerland.
Pezet
Roger
R
Tabacchi
Raphael
R
D000872:Anthocyanins / Q000032:analysis; D044946:Biflavonoids; D002392:Catechin / Q000032:analysis; D007536:Isomerism; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry; D044945:Proanthocyanidins; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013057:Spectrum Analysis; D013634:Tannins / Q000032:analysis*; D027843:Vitis / Q000737:chemistry*
D000872:Anthocyanins; D044946:Biflavonoids; D010936:Plant Extracts; D044945:Proanthocyanidins; D013634:Tannins; C013221:proanthocyanidin; C017674:procyanidin; D002392:Catechin