Evolution of the crown procyanidins during wine making and aging in bottle

Proteins play a significant role in the colloidal stability and clarity of white wines [1]. However, under conditions of high temperatures during storage or transportation, the proteins themselves can self-aggregate into light-dispersing particles causing the so-called protein haze [2]. Formation of these unattractive precipitates in bottled wine is a common defect of commercial wines, making them unacceptable for sale [3]. Previous studies identified the presence of phenolic compounds in the natural precipitate of white wine [4], contributing to the hypothesis that these compounds could be involved in the mechanism of protein haze formation.

Enzymatic browning[1] is an oxidation process that occurs in many foods that increases the brown colour[2]. This problem is especially harmful in the wine industry[3]. especially when the grapes are infected by grey rot since this fung release the oxidative enzyme laccase[4]. In the particular case of red wines, the presence of laccase implies the deterioration of the red colour and can even cause the precipitation of the coloring matter (oxidasic haze)[5].

Wine grape berries respond to postharvest treatments with specific gaseous elicitors in terms of metabolic changes and composition. Short-term (3 days) high (30 KPa) CO2 treatment affects phenol compound concentration in skins of ‘Trebbiano toscano’ berries.

On peut être surpris de l’existence d’un vignoble de vins liquoreux, le vignoble des Coteaux du Layon, dans une zone septentrionale à la limite Nord de la culture de qualité de la vigne et ce d’autant plus que le cépage de ce vignoble, le Chenin ou Pineau de la Loire, est un cépage semi tardif. La première explication est à rechercher au niveau des facteurs naturels (données climatiques et géopédologiques) permettant la réalisation de ce type de produit. Il est nécessaire de souligner ici l’importance de chaque paramètre du terroir pris dans im sens large (géopédologique et climatique) et que toute variation de l’un d’entre eux, même non perceptible en première analyse à l’homme, peut avoir des incidences déterminantes sur la qualité des vins.

The available plant diversity is maintained in global genetic collections and germplasm banks. One of the main objectives of the study of the genetic material of vine still conducting research to characterize the genotypes and the creation of new varieties. The main ampelographic collection of the country, the largest in the Balkans, is located at the Athens Vine Institute in Lykovrisi, Attica, in an area of 70 acres. It contains more than 800 varieties, most of which are indigenous. The Institute is conducting research on the genetic improvement of native varieties and the creation new winemaking and table grape varieties of high productivity, grape quality, resistance to fungal diseases and their adaptability to stresses using the hybridization method using European high-quality varieties.