How can yeast modulate Divona’s aromatic profile?

Abstract

Volatile thiols play a key role in the aromatic expression of white wines, contributing to notes such as passion fruit, grapefruit, and herbal nuances [1]. These compounds, present as non-volatile precursors in grapes, require enzymatic activation to be released and realize their aromatic potential. The enzymatic activity of yeast during fermentation influences the release and transformation of thiol precursors, thereby modulating their final concentration in wine [2]. Divona is a new Swiss grape variety with quantitative trait loci for resistance to fungi: Rpv10, Rpv 3.3 (mildew), Ren3, Ren9 (powdery mildew), Rgb1 (black rot) and average susceptibility to grey rot (Botrytis cinerea) [3]. It produces wines with a fruity bouquet of exotic fruit and citrus, with occasional floral and mineral notes. The aim of this work is to see how the use of thiol-releasing yeasts can influence the composition and aromatic profile of Divona wines. In 2020, 2 thiol- revealing yeasts were compared with a control yeast on a Divona must from the experimental vineyard in Pully, VD, Switzerland. The presence of aromatic precursors in the must was measured by LC-MS. The wines were vinified at the Changins experimental winery, VD, Switzerland. Classical wine parameters were analysed by WineScan©, FOSS, thiols were measured by UHPLC-MS/MS and terpenes by GC-MS. The wines were also subjected to a sensory profile analysis. The results obtained with Divona were compared with similar trials on Sauvignon blanc carried out at the Wädenswil experimental estate. The results show that the Divona grape variety has thiol precursors in the must and the use of special yeasts can influence the final quantity of 3MH. The quantity of 4MMP is very low compared with the quantities found in Sauvignon blanc wines. Terpene concentrations are below the perception threshold. The sensory analyses showed that the general appreciation is not linked solely to the quantity of 3MH in the wine and takes into account the overall balance of the wine. The use of such thiol-releasing yeasts can influence the aromatic expression of the new Divona grape variety. Improving our knowledge of resistant grape varieties such as Divona will help to integrate them into the wine industry.

References

[1] Roland, A., et al., Varietal thiols in wine: discovery, analysis and applications. Chemical reviews, 2011. 111(11): p. 7355-7376.

[2] Swiegers, J.H., et al., The influence of yeast on the aroma of Sauvignon Blanc wine. Food Microbiology, 2009. 26(2): p. 204-11.

[3] Spring J.-L., et al., Divona, nouveau cépage blanc résistant aux principales maladies de la vigne sélectionné à Agroscope Revue suisse de viticulture arboriculture horticulture, 2018. 50(5): p. 286-296.