Garnacha Tintorera-based sweet wines: Detailed phenolic composition by HPLC/DAD–ESI/MS analysis

Abstract

Sweet wines are traditionally elaborated in Galicia (the N.W. corner of Spain). The denomination of origin (DO) Valdeorras, one of the five DOs in Galicia, wants to promote the production and marketing of new sweets wines. The first one is made with dried red grapes Vitis vinifera L. Garnacha Tintorera (GNSW); this cultivar is a teinturier cultivar which has excellent potential to produce wines from raisined grapes. The second one, a fortified sweet wine aged in oak barrels (GFSW). Additionally a dry young wine (GBW) was produced from the same variety. Their aroma profiles and chromatic characteristics (determined by simple spectrophotometric methods) have been previously established. Now, proanthocyanidins, flava-3-ol monomers, anthocyanins, phenolic acids, flavonols and resveratrol were determined by HPLC, for the same three wines. The highest concentration of total proanthocyanidins (PAs) was evaluated in the GBW (525mgL−1), which was about 2-fold the concentration in the GNSW (236mgL−1) and about more 10-fold the concentration in the GFSW (44mgL−1). No apparent difference in the aDP (mean degree of polymerisation) was observed for the GBW (1.9) and the GNSW (2.1), whereas a slightly lower value was obtained for the GFSW (1.5). Total anthocyanin concentration was described as follow as GBW: 390mgL−1≫GNSW: 57mgL−1>GFSW: 25mgL−1, which indicates that sweet wines were polymerised in great extent. Only vitisin A and B were found the main concentration in GFSW when compared to GBW by the ageing process. In sweet wines, phenolic acids (hydroxybenzoic and hydroxycinnamic acids) and flavonols were lowest when compared to GBW and resveratrol not was found in sweet wines.