The same behaviour was observed for epicatechin. In agreement with other studies (Prieur et al., 1994), gallocatechin and epigallocatechin were present at lower levels. The percentage of gallocatechin ranged from 6% to 23% of the total monomers. Among the studied samples Sangiovese 2007 and Cabernet Franc 2006 and 2007 variety samples contained ∼23% and 15% of the total monomers

as gallocatechin, respectively. Epicatechin gallate was responsible for ∼6% of the free monomers quantified in this study. Among the proanthocyanidins oligomers, dimers B1 and B2 are present at higher concentrations in grapes and, consequently, in wine (Monagas et al., 2003). PA B1 was the main dimer in the wine samples, contributing with more than 60% of the dimers, as also reported in other studies (Cosme, Ricardo-da-Silva, & Laureano, 2009). PA B1 is the

main dimer in grape skins buy PLX-4720 and during wine fermentation it is easier to extract than PA B2, present in high concentrations in seeds. Thus, for the varieties investigated, flavan-3-ols from grape skins contributed more to the wine flavan-3-ol composition, in agreement with results reported in the literature (Fernández, Kennedy, & Agosin, 2007). Merlot and Syrah wine samples showed the highest values for the sum of total monomers and dimers flavan-3-ols, especially for Merlot 2007 (118 mg L−1). Regarding percentage distribution, Cabernet Franc and Syrah wines, 2006 vintage, presented the highest monomer contents, followed by Sangiovese and Cabernet Franc, 2007 vintage, Merlot MK-1775 manufacturer and Syrah, 2006 vintage, and Merlot and Syrah, 2007 vintage. The highest proportions of dimers were present in the samples of Merlot and Syrah from 2007 vintage (up to 51%), a finding previously observed in the Spanish wines Tempranillo, Graciano and Cabernet Sauvignon by Monagas et al. (2003). It is interesting to note

that both the vintage and Flavopiridol (Alvocidib) grape variety influenced the flavan-3-ol composition of the wines (p < 0.05), but with different behaviours according to the vintage. This was also observed by Chira et al. (2009), who evaluated, for two consecutive vintages, the tannin composition from the skin and seed extracts of Merlot and Cabernet Sauvignon grapes in Bordeaux, France. Grape and wine PAs are constituted of several oligomers and polymers with a very complex molecular structures. Phloroglucinolysis, which is the depolymerisation of PAs in an acid environment in the presence of phloroglucinol, gives access to important information regarding PA composition (Kennedy & Jones, 2001). Data on the PA structural composition of wine samples are shown in Table 3. Structurally, PAs present in wine samples comprised catechin, epicatechin, gallocatechin and epicatechin gallate as terminal and extension units, only gallocatechin not being detected as an extension unit (Table 3).