On-vine withering process of 'Moscato bianco' grapes: effect of cane-cut system on volatile composition.

Background: Cane-cut on-vine withering is a grape dehydration technique used for dry and sweet wine production. The aim of this work was to study the influence of the cane-cut technique applied at harvest to Moscato bianco grapes during the on-vine withering process to produce dehydrated berries with a different chemical composition and a volatile profile.

Results: After 24 days of dehydration, an on-vine withering system using the cane-cut technique induced an increase in the total volatile content compared with grapes produced with a normal on-vine withering process.

Comparison of fortified, sfursat, and passito wines produced from fresh and dehydrated grapes of aromatic black cv. Moscato nero (Vitis vinifera L.).

Moscato nero d'Acqui is an Italian aromatic black winegrape variety characterized by a low content of anthocyanins (mostly tri-substituted), a satisfactory content of high molecular mass tannins, and a fair amount of terpenes. The grapes were subjected to a postharvest dehydration process under controlled thermohygrometric conditions (16-18°C, 55-70 RH%, 0.6m/s air speed) with the aim to produce three different special wine types (fortified, sfursat, and passito) from fresh, partially dehydrated (27°Brix), and withered (36°Brix) grapes, respectively.

Extraction kinetics of anthocyanins from skin to pulp during carbonic maceration of winegrape berries with different ripeness levels.

The evolution of the content and profile of anthocyanins was studied in the skin and pulp of Gamay winegrapes during twelve days of carbonic maceration. The ripening effect was also investigated using berries belonging to two density classes (A=1094-1100 kg/m(3) and B=1107-1115 kg/m(3)). The ripest berries showed a higher extraction yield, even though the differences among density classes tended to decline towards the end of the process, and few significant differences were found in the anthocyanin profile.

Influence of grape density and harvest date on changes in phenolic composition, phenol extractability indices, and instrumental texture properties during ripening.

Changes in the phenolic composition, phenol extractability indices, and mechanical properties occur in grape berries during the ripening process, but the heterogeneity of the grapes harvested at different ripening stages affects the reliability of the results obtained. In this work, these changes were studied in Nebbiolo grapes harvested during five consecutive weeks and then separated according to three density classes. The changes observed in chemical and mechanical parameters through the ripening process are more related to berry density than harvest date.

Mechanical properties, phenolic composition and extractability indices of Barbera grapes of different soluble solids contents from several growing areas.

Phenolic compounds, extractable from grape skins and seeds, have a notable influence on the quality of red wines. Many studies have clearly demonstrated the relationship between the phenolic composition of the grape at harvest time and its influence on the phenolic composition of the red wine produced. In many previous works the evolution of phenolic composition and relative extractability was normally studied on grapes sampled at different times during ripening, but at the same date the physiological characteristics of grape berries in a vineyard are often very heterogeneous.