Terroir, climat et sol

The separation of different grape juice press fractions is an important step in the production of sparkling base wines. A complete press cycle for this style of wine is a series of pressure increases (squeezes) resulting in variations in juice composition during the press cycle. After alcoholic fermentation, wines obtained from grape juices also exhibit strong differences for numerous characteristics. Nevertheless, there is no statistical study of the impact of the press cycle on grape juices and wine colour/composition. So, the aim of this study (vintage 2018) was to investigate the changes in composition and colour parameters of Pinot noir and Pinot meunier grapes juices, as well as their corresponding wines, during the pressing cycle.

AIM: The increasing incidences of wildfires in wine grape growing regions pose a significant risk. Persistent exposure to smoke can compromise the quality and value of wine grapes and adversely affect wines made from smoke exposed grapes.

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).

Aims: Shiraz is the most widely cultivated grape variety in Australia, and is grown under a range of viticultural and climatic conditions. Given its importance to the Australian wine sector, a number of studies have been conducted in recent years which involved a comprehensive assessment of grape composition, in order to objectively predict wine quality and style outcomes.

Context and purpose of the study. The quality of table grape clusters significantly affects consumer perception and market value, with berry size, texture, color, and overall appearance playing key roles.