Flavonoids in Gran Negro berries collected from shoulders and tips within the cluster,and comparison with Brancellao and Mouratón varieties

Galicia (the north-western corner of Spain) is a Spanish region with several old-traditional winegrowing areas. Vitis vinifera L. cv. Mencía is one of the most often used to produce quality red wines but the tendency of the world wine-making market is to reward the production of wines that have particular and differentiated characteristics. In Galicia, there are other red cultivars such as Gran Negro which were not exploited for their potential to produce quality red wines. Dynamics of anthocyanin and flavonol accumulation in Gran Negro berries were studied separately in two different positions within the cluster (tips and shoulders) during 30 days before harvest to assess the existence of different polyphenol quality in both positions and as a consequence, red wines with different qualities. Dynamics of anthocyanins over ripening confirmed that anthocyanins presented upward trends (from 1510 to 1727 mg/kg in tips; and from 1532 to 1728 mg/kg in shoulders) but dynamics of flavonols confirmed that maximum values were reached and stabilised thirty days before harvest (from 45 to 39 mg/kg in tips; and from 49 to 45 mg/kg in shoulders). No differences were observed in anthocyanin and flavonol contents collected from tips and shoulders which indicates that is not necessary to harvest them separately. The results from Gran Negro were compared with those of Brancellao and Mouratón.     

Anthocyanins and flavonols berries from Vitis vinifera L. cv. Brancellao separately collected from two different positions within the cluster

Galicia (N.W. Iberian Peninsula) is a Spanish region with several old-traditional winegrowing areas. Vitis vinifera L. cv. Mencía is one of the most often used to produce quality red wines in the five Galicia Denomination of Origin. However, there are traditional cultivars such as Brancellao, which were not exploited for their potential to produce quality red wines. Dynamics of anthocyanin and flavonol accumulation were studied separately in two different positions within the cluster (tips and shoulders), during 30 days before harvest. The objective of separating berries is to assess the existence of different polyphenol quality in both positions; as a consequence, the selection and harvest of those berries with a higher content of anthocyanins and flavonols could produce red wines with different qualities. Derivatives of five anthocyanins (malvidin, peonidin, petunidin, delphinidin and cyanidin) were detected in skins at both positions within the cluster. Anthocyanin contents stabilized in the 30 days prior to harvest in the berries from the shoulders whereas they continue to increase in those from the tips. Derivatives of six flavonols (quercetin, myricetin, kaempherol, laricitrin, isorhamnetin and syringetin) were detected in skin and flesh at both positions within the cluster. Dynamics of anthocyanins (from 400 to 515 mg/kg in tips; and from 598 to 574 mg/kg in shoulders) and flavonols (from 19 to 29.3 mg/kg in tips; and from 22.7 to 29.4 mg/kg in shoulders) over ripening confirmed that these polyphenols presented upward trends. Therefore, it is not necessary to harvest Brancellao berries separately and a high quality red wine will be obtained with berries from entire clusters regarding these compounds.     

Aroma potential of Brancellao grapes from different cluster positions

In this study the presence of aroma compounds in grapes of Brancellao (Vitis vinifera L.) was investigated in order to obtain its aroma potential fingerprint. It is well known that differences exist in aromatic compounds amongst grapevine varieties at ripening stages. Within the framework of an increasingly competitive market, the chance of obtaining different wines from vines of the same variety grown at the same vineyard is becoming of increasing importance. This can be done through the managing of the vineyard, but also some wineries have assayed the separation of the tip and shoulder berries of the clusters of a specific variety with this objective. In this work it is evaluated that, in the final stages of maturation, differences exist in the probable alcoholic degree, total acidity of the must, as well as in the aromatic composition of skin and flesh of berries coming from the tips and shoulders of the clusters. Gas chromatography coupled to mass spectrometry (GC-MS) was used to determine the aromatic composition, in the skin and flesh of each sample, either tip or shoulder berries from the clusters. The obtained results showed that there was not variability for the probable alcoholic degree and total acidity between the shoulders and tips, whereas there was variability for their aromatic composition. For the berries from the tips of the clusters most of volatiles were found in the flesh (except aldehydes) and spicy and floral nuances (with the only exception of β-ionone) were in higher proportions. For the berries from the shoulders of the clusters, most of volatiles were found in the skin (monoterpenes, norisoprenoids, aldehydes, and C₆ alcohols), where the flesh was slightly richer in aromatic alcohols, volatile phenols and pantolactone; β-ionone and herbaceous nuances were in higher proportions. These results are promising for those wineries that are considering the chance of separating berries from tips and shoulders of the clusters for the elaboration of different quality wines.     

Pattern recognition of three Vitis vinifera L. red grapes varieties based on anthocyanin and flavonol profiles,with correlations between their biosynthesis pathways

The presence of anthocyanins and flavonols in three selected red grape varieties was investigated, in order to use their polyphenolic characterisation as a fingerprint. Berry skins of Gran Negro grapes were characterised by the presence of high content of malvidin- and peonidin-3-O-glucoside; Mouratón grapes, by the presence of high content of petunidin- and delphinidin-3-O-glucoside; and Brancellao grapes, by the presence of high content of cyanidin-3-O-glucoside. The main flavonols found included the 3-O-glucosides of quercetin, myricetin, kaempferol, laricitrin, isorhamnetin and syringetin. Using cluster analysis and principal components analysis, Gran Negro could be characterised by their content of isorhamnetin-3-O-glucoside and syringetin-3-O-glucoside and, along with Mouratón, by their myricetin conjugates. Flavonol profile could not provide a fingerprint of Brancellao variety. Stepwise discriminant analysis was performed in order to find the polyphenolic compounds, which characterised the selected grape varieties. Finally, anthocyanin and flavonol profiles in red grapes were compared and results confirmed that biosynthesis of flavonols is closely related to that of anthocyanins.