WHAT’S FUTURE FOR SANTORINI’S VITICULTURE IN THE CONTEXT OF CLIMATE CHANGE

The overall quality of aged wines is in part due to the development of complex aromas over a long period (1.) The apparition of this aromatic complexity depends on multiple chemical reactions that include the liberation of odorous compounds from non-odorous precursors. One example of this phenomenon is found in dimethyl sulphide (DMS) which, with its characteristic odor truffle, is a known contributor to the bouquet of premium aged wine bouquet (1). DMS supposedly accumulates during the ten first years of ageing thanks to the hydrolysis of its precursor dimethylsulfoniopropionate (DMSp.) DMSp is a possible secondary by-product from the degradation of S-methylmethionine (SMM), an amino acid iden- tified in grapes (2), which can be metabolized by yeast during alcoholic fermentation.

The sensory characteristics of wine are a topic studied by several researchers over time, but it continues to be a current and challenging subject. These characteristics are fundamental for the consumer acceptability, which has increasingly aroused their interest to modulate them in line with current market trends and innovation demands. The wine physical-chemical and sensory properties depend on a wide set of factors: they begin to be designed in the vineyard and are later constructed during the various stages of winemaking. Afterwards, the wine is placed in bottles and stored or commercialized.

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.
First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).

The positive contribution of toasted vine-shoots (SEGs, Shoot from vines – Enological – Granule) used in winemaking to the chemical and sensory profile of wines has been widely proven. However, the combination of this new enological tool with other winemaking technologies, such as micro-oxygenation (MOX), has not been studied so far. It is known that micro-oxygenation is used in wineries to stabilizes color, improves structure or combining with oak alternatives products to achieve a more effective aroma integration of wines. For that, its implementation in combination with SEGs could result in differentiated wines.

Yeast co-inoculations in winemaking have been investigated in various applications, but most often in the context of modulating the aromatic profiles of wines. Our study aimed to characterize S. cerevisiae interactions and their impact on wine by taking an integrative approach. Three cocultures and corresponding pure cultures of S. cerevisiae were characterized according to their fermentative capacities, the chemical composition and aromatic profile of the associated Chardonnay wines. The various strains studied within the cocultures showed different behaviors regarding their development.