Characterizing the molecular basis of the differences in aromatic precursors found in commercial clones of Vitis vinifera cv. Tannat

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.

Grape (Vitis vinifera) is one of the world’s oldest agricultural fruit crops, grown for wine, table grape, raisin, and other products. One of the factors that can cause a reduction in the grape growing area is temperature rise due to climate change. Elevated temperature causes changes in grapevine phenology and fruit chemical composition. Previous studies showed that grape varieties respond differently to a temperature shift of 1.5°C; few varieties had difficulties in the fruit development or could not reach the desired Brix level.

Nowadays, the entire viticultural and enological process is wisely thought out according to the style of wine to be produced and the local climatic conditions. Acquiring the approach of a technical management route specific for wine production remains a complex learning process for students. To enhance such learning, The Ecole d’Ingénieurs de PURPAN (PURPAN), an engineering school located in Toulouse southwest France, has recently developed Creativini, a collaborative card game in English made of 150 cards spread into 14 batches. Students in groups of 3 to 6 must design a technical production route, from plant material to bottling.

The isUP-AgrO project aims to enhance the capability of ISOPlexis – Centre of Sustainable Agriculture and Food Technology, a research unit from the University of Madeira, an outermost region of Portugal.

The gustatory balance of wines relies on sweetness, bitterness and sourness. In dry wines, sweetness does not result from the presence of residual sugar as in sweet wines, but is due to other non-volatile compounds. Such taste-active compounds are released during winemaking, by grapes, yeasts or oak wood and belong numerous chemical families [1]. Beyond this diversity, stereochemistry of molecules can also influence their sensory properties [2]. However, the molecular determinants associated with this taste have only been partially elucidated. Astilbin (2R, 3R) was recently reported to contribute to wine sweetness [3]. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). These compounds have already been observed in natural products, but never in wine. This work aimed at assaying their presence for the first time in wines as well as their taste properties.The isomers were synthesized from astilbin and purified by semi-preparative HPLC.