%0 Journal Article
%T Recent Applications of Mass Spectrometry in the Study of Grape and Wine Polyphenols
%A Riccardo Flamini
%J ISRN Spectroscopy
%D 2013
%R 10.1155/2013/813563
%X Polyphenols are the principal compounds associated with health benefic effects of wine consumption and in general are characterized by antioxidant activities. Mass spectrometry is shown to play a very important role in the research of polyphenols in grape and wine and for the quality control of products. The soft ionization of LC/MS makes these techniques suitable to study the structures of polyphenols and anthocyanins in grape extracts and to characterize polyphenolic derivatives formed in wines and correlated to the sensorial characteristics of the product. The coupling of the several MS techniques presented here is shown to be highly effective in structural characterization of the large number of low and high molecular weight polyphenols in grape and wine and also can be highly effective in the study of grape metabolomics. 1. Principal Polyphenols of Grape and Wine Polyphenols are the principal compounds associated to health benefic effects of wine consumption. A French epidemiological study performed in the end of 1970s reported that in France, despite the high consumption of foods rich in saturated fatty acids, the incidence of mortality from cardiovascular diseases was lower than that in other comparable countries. This phenomenon was called ¡°the French paradox¡± and was related to the beneficial effects of red wine consumption [1]. In general; polyphenols have antioxidant activities. Their activity as peroxyl radical scavengers and in the formation of complexes with metals (Cu, Fe, etc.) has been shown by in vitro studies. Moreover, the ability of polyphenols to cross the intestinal wall of mammals confers their biological properties. Flavan-3-ols are one of the principal classes of grape polyphenols which include (+)-catechin and (£¿)-epicatechin, and their oligomers called procyanidins, proanthocyanidins, and prodelphinidins. B-type and A-type procyanidins and proanthocyanidins (the latter are condensed tannins) are present in the grape skin and seeds; tannins are mainly present in seeds, and prodelphinidins are polymeric tannins composed of gallocatechin units (structures in Figure 1). During winemaking the condensed (or nonhydrolyzable) tannins are transferred to the wine and contribute strongly to the sensorial characteristic of the product. In the mouth, the formation of complexes between tannins and saliva proteins confers to the wine the sensorial characteristic of astringency: bitterness and astringency of wine is linked to tannins structure, in particular galloylation degree (DG) and polymerization degree (DP) of flavan-3-ols [2, 3].
%U http://www.hindawi.com/journals/isrn.spectroscopy/2013/813563/