The key role of vineyard parcel in modifying flavor compounds of Cabernet Sauvignon grapes

The quality of a wine is largely related to the balance between its sourness, bitterness and sweetness. Recently, molecules coming from grapes have been showed to notably contribute to sweet taste of dry wines. To study the viticultural and oenological parameters likely to affect their concentration, their quantification appears of high interest and subsequently requires powerful analytical techniques. Therefore, a new method using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) was developed and validated to quantify epi-DPA-3′-O-β-glucopyranoside acid (epi-DPA-G) and astilbin, sweet molecules identified in wine. Three gradients were tested on five different C18 columns (Hypersil Gold, HSS T3, BEH, Syncronis and Kinetex).

Brazil is historically known at the international wine market as an importer, eventhough in the last decades there was an increase in quantity and quality of the internal production. Nowadays, about 40% of fine wines comsuption of the country are national ones. The main production region is called Serra Gaúcha, where the natural conditions are heterogeneous and viticulture is develloped in small properties, mainly done by the owners family.

Wine is a solution containing abundant volatile compounds which contribute to their aroma. Many of them are produced by yeast as metabolism by-products. Different yeast strains produce different volatile profiles. The possibility of studying the evolution of volatile compounds during fermentation, using sampling methods that not alter the volume of fermentation media, is of great interest. In spite of this, non-invasive methods to monitoring the evolution of volatile profile during fermentation have been seldom used. The goals of this work were to use by first time the headspace sorptive extraction (HSSE) as non-invasive method to monitor the evolution of volatile profiles throughout alcoholic fermentation and to study the changes on volatile profiles produced by Saccharomyces cerevisiae and Lachancea thermotolerans during fermentation of a must with high sugar content.

The traditional pruning system in Piedmont (North-West Italy) is the Guyot system; it requires trained personnel, difficult to find, and it does not permit the mechanization of winter pruning, thus it is very expensive. An alternative technique that could allow the reduction of the vineyard management costs could be the spur-pruning which is simpler to perform and fully mechanized.

Ellagitannins are the main oak wood phenolic compounds that contribute to wine and spirits organoleptic quality (color, astringency, bitterness)(1-3). Given the lack of knowledge regarding their composition and evolution in spirits, the objectives were to follow their extraction kinetic in Cognac “eaux-de-vie” matured in barrel representing different toasting and to observe their evolution and structural modifications during aging. METHODS: Eight different toasting levels were used for studying the impact of the toasting on ellagitannins composition. Two verticals (1978-2018) of “eaux-de-vie” samples coming from two terroirs were analyzed in order to observe ellagitannins evolution during aging. The above analyses were conducted using HPLC-Triple Quadrupole mass spectrometer (4) and the unknown compounds were identified by UPLC-Q-TOF, purified by preparative HPLC prior to 1D/2D-NMR analysis.