Stability of 3-mercaptohexanol during white wine storage in relationship to must pre-fermentative fining

The importance of polyphenols, which are present in many vegetables and grapes too, is well-know and documented. Specific research works about the red grape

Botrytis cinerea is a fungus that causes common infection in grapes and other fruits. In winemaking, its presence can be both considered desirable in the case of noble rot infection or undesirable when grey rot is developed. This fungus produces an extracellular enzyme known as laccase which is able to cause oxidation of phenolic compounds present in must and wine, causing most of the times a decrease in its quality and problems during the winemaking process [1]. Material and methods: Three B. cinerea strains (B0510, VA612 and RM344) were selected and grown in a liquid medium adapted from one previously described [2]. The enzyme was isolated by tangential ultrafiltration of the culture medium using a QuixStand system equipped with a 30 KDa filtration membrane.

The rising trend of moderate wine consumption as a part of a healthy lifestyle promotes white wines with higher phenolic content because of their bioactive properties. Duration and temperature of the maceration process have a marked impact on the content and composition of wine phenolics. The aim of this study was to explore the effect of applying maceration processes of different durations and temperature on total phenolic content and flavan-3-ol compounds concentration of Malvazija istarska (Vitis vinifera L.) wines, an autochthonous Croatian white grape variety. Vinification took place at the Institute of Agriculture and Tourism (Poreč) where pre-fermentative two days cryomaceration treatment at 8 °C (CRYO), seven days maceration treatment at 16 °C (M7), and prolonged post-fermentative maceration treatments at 16 °C for 14 days (M14), 21 day (M21), and 42 days (M42) were studied and compared to non-maceration control treatment (C). Total phenolic content was determined by the Folin-Ciocalteu colorimetric method using a UV/VIS spectrophotometer and the results were expressed as gallic acid equivalents (mg/L GAE).

Among the different management techniques in Viticulture, which have
been developed with the purpose of optimizing the interception of sunlight, the photosynthetic capacity of
the plant and the microclimate of the clusters, especially in varieties that show excess vigor, the management of defoliation presents great importance. The defoliation consists of the removal of leaves that cover or that are in direct contact with the curls, which can cause physical damages in the berries, and aims to balance the relation between part area and number of fruits, providing the aeration and insolation in the interior of the vineyard, as well as reduce the incidence of rot in order to achieve greater efficiency in phytosanitary treatments and quality musts.

The maturation patterns process has been very studied. In particular the modelization of the sugars and titratable acidity during the ripening period was an important approach, in particular for the prediction of harvest date (Barillere et al., 1988; Jourion et al.,1987; Maujean et al., 1983; Scienza, 1989). In Oltrepò Pavese, the widest viticultural district of Lombardy – Northern Italy – (about 15000 hectares), grape maturation trends shows high variability, due to the large variation in environmental characteristics of vineyards (altitude, exposure, soil type, mesoclimate) and to “cultivar x environment” interaction.