Changes of Flavan-3-ols with Different Degrees of Polymerization in Seeds of ‘Shiraz’, ‘Cabernet Sauvignon’ and ‘Marselan’ Grapes after Veraison

Abstract

Flavan-3-ols consist of flavan-3-ol monomers and polymers with different degrees of polymerization (DP). In this study, flavan-3-ol extracts from grape seeds were well separated into three fractions including monomers, oligomers (2 < DP < 10) and polymers (DP > 10), by means of normal-phase HPLC-MS. The different patterns of these three fractions were analyzed in three Vitis vinifera cultivars (‘Shiraz’, ‘Cabernet Sauvignon’ and ‘Marselan’) seeds from veraison to harvest. The results showed: (1) polymers were the main form of flavan-3-ols in grape seeds and monomers accounted for only a small proportion; (2) the contents of flavan-3-ol monomers in the seeds of three grape cultivars all exhibited a gradually decreasing trend with a little fluctuation, whereas the patterns of the change of contents of oligomers and polymers were extremely different among grape cultivars; the contents of flavan-3-ol oligomers were enhanced in the seeds of ‘Cabernet Sauvignon’, but were reduced in the other two cultivars; (3) with regard to the proportion of flavan-3-ols with a certain DP to total flavan-3-ols, both flavan-3-ol monomers and flavan-3-ols with low DP fell in proportion, while the flavan-3-ols with high DP increased correspondingly. These findings indicate that flavan-3-ol polymerization in developing seeds is variety-dependent and may be genetically regulated.

Changes in Polyphenolic Content and Antioxidant Activity of Grapes cv Vranac During Ripening

“…In the seeds of the Vranac variety, (-)-epicatechin was the major flavan-3-ol monomer, while (-)-epicatechin gallate was present in trace amounts, which is consistent with data previously reported (Butkhup et al, 2010;Liu et al, 2010). Other authors have reported that (+)-catechin was the most abundant flavan-3-ol monomer in Cabernet Sauvignon and Marselan seeds (Kennedy et al, 2000a;Downey et al 2003;Liu et al, 2010). Lacopini et al (2008) reported concentrations of (+)-catechin in grape seeds of Merlot, Cabernet Sauvignon, Canaiolo, Colorino Vino, Foglia Tonda and Montepulciano of 1.38, 1.41, 1.40, 1.24, 0.67 and 2.05 mg/g DM respectively, and slightly lower concentrations of (-)-epicatechin at 1.31, 1.27, 2.05, 0.89, 0.47 and 1.64 mg/g DM respectively.…”

“…The composition of individual flavan-3-ols of the Vranac variety (Table 3) shows that flavan-3-ols are mostly concentrated in the seeds. They were also present in the skins, although in a significantly lower concentration, which is in agreement with reported data (De Freitas et al, 2000;Revilla & Ryan, 2000;Sun et al, 2001;Downey et al, 2003;Lacopini et al, 2008;Obreque-Slier et al, 2010;Liu et al, 2010). Three flavan-3-ol monomers, (+)-catechin, (-)-epicatechin and (-)-epicatechin gallate, were detected in the grape seeds.…”

“…Three flavan-3-ol monomers, (+)-catechin, (-)-epicatechin and (-)-epicatechin gallate, were detected in the grape seeds. In the seeds of the Vranac variety, (-)-epicatechin was the major flavan-3-ol monomer, while (-)-epicatechin gallate was present in trace amounts, which is consistent with data previously reported (Butkhup et al, 2010;Liu et al, 2010). Other authors have reported that (+)-catechin was the most abundant flavan-3-ol monomer in Cabernet Sauvignon and Marselan seeds (Kennedy et al, 2000a;Downey et al 2003;Liu et al, 2010).…”

“…The concentration of (+)-catechin remained relatively constant from véraison to all harvest dates after véraison, varying between 0.85 and 1.12 mg/g. Others have reported similar flavan-3-ol accumulation in grape seeds during grape ripening (Kennedy et al, 2000a;Ristic & Iland, 2005;Liu et al, 2010;Obreque-Slier et al, 2010). This is due to the fact that this class of polyphenols has already formed before véraison (De Frietas et al, 2000;Kennedy et al, 2000aKennedy et al, , 2001Downey et al, 2003).…”

Influence of berry ripeness on concentration, qualitative composition and extractability of grape seed tannins

“…The evolution of polymeric tannins in all three varieties reached a maximum at veraison and then decreased towards ripeness (Figure 3). This decrease was observed by Liu et al. (2010) for Cabernet Sauvignon.…”