Exploring diversity of grapevine responses to Flavescence dorée infection

This study investigated if compositional differences between Shiraz and Cabernet Sauvignon grape varieties could influence the production of yeast-derived compounds. This work was based on the analysis of 40 experimental red wines made in triplicate fermentations from grapes harvested from two consecutive vintages in New South Wales (Australia). Grapes were picked at three maturity stages using berry sugar accumulation as physiological indicator, from nine commercial vineyards located in three different climatic regions (temperate, temperate-warm and warm-hot). A range of 30 yeast-derived wine volatiles including esters and alcohols were quantified by HS/SPME-GC/MS. Ammonia, amino-acids and lipids were analysed in the corresponding grapes. The juice total soluble solids (°Brix) in addition to the wine alcohol and residual sugar levels were also measured. The influence of grape maturity on wine ester composition was also variety dependent, particularly for higher alcohol acetate and ethyl ester of branched acids. This study highlights that varietal differences observed in Shiraz and Cabernet Sauvignon wines involve fermentation-derived compounds irrespective of the site (soil, climate, viticultural practices).

During winemaking and aging, potassium hydrogen tartrate (KHT) and, to a lesser extent, calcium tartrate (CaT) crystals can precipitate, especially when grape must or wine is exposed to low temperatures [1].

Unlike table wines, Madeira Wine (MW,17-22% ABV) benefits from a long aging period under thermo-oxidative aging conditions, during which it gains its unique and complex flavour. A broad study is ongoing and aims to assess if the differences in the storage conditions impact significantly the evolution of MWs during canteiro aging. Considering that polyphenols have a significant role in the wine aging, we intended to appraise if there are significant differences in the evolution trends of polyphenols of MWs aging in different cellars under canteiro. Different MWs were aged into brand-new oak casks in two different wine cellars, one in Funchal (B) and other in Caniçal (Z). Temperature and humidity data were sensor recorded. RP-HPLC-DAD was used to perform the identification and quantification of polyphenols [1]. CIELab parameters were also assessed, using an UV-Vis spectrophotometer.

Typically, subjective, and visual methods are used by grape growers to assess harvest maturity. These methods may not accurately represent the maturity of an entire vineyard – especially if extensive and representative sampling was not used. New technologies have been investigated for improved harvest management decisions. Spectroscopy methods utilizing the near-infrared region of the light spectrum is one such technology investigated as an alternative to classic methods and particularly the application of hyperspectral imaging (HSI) has recently gained attention in research. HIS is a spectroscopic technique that obtains hundreds of images at different wavelengths collecting spectral data for each pixel in the sample i.e., providing both spectral and spatial data.

Le sol est un facteur important permettant la croissance de la vigne. Les propriétés physiques et chimiques, mais aussi microbiologiques ont une influence sur beaucoup des fonctions du sol comme la structure, le drainage, la fertilité, déterminant la vigueur des plantes et le potentiel œnologique des raisins.