Projects / Programmes
Improvement of Slovenian white wines through better expression of varietal aroma
| Code |
Science |
Field |
Subfield |
| 4.03.07 |
Biotechnical sciences |
Plant production |
Technology of vegetal origin food |
| Code |
Science |
Field |
| T430 |
Technological sciences |
Food and drink technology |
| Code |
Science |
Field |
| 4.01 |
Agricultural and Veterinary Sciences |
Agriculture, Forestry and Fisheries |
white wines, aromatic potential, volatile thiols, thiol precursors, vinification
Researchers (8)
Organisations (2)
Abstract
Sulfur-containing compounds which contribute to desirable fruity (grapefruit/citrus, passion fruit/tropical) aromas in Sauvignon Blanc and Malvasia are referred to as volatile or varietal thiols. Their presence is considered essential for creating unique varietal flavour attributes which contribute positively to wine. A comprehensive research (from vineyard to fermentation) will study a better expression of volatile (varietal) thiols in two varieties which will offer winegrowers new knowledge to improve a quality of white wines. A research will evaluate vineyard (soil, climate) characteristic on thiol aromatic potential in two winegrowing regions (Slovenska Štajerska, Primorska) in Sauvignon Blanc and Malcasia varieties respectively. For the first time, secondary metabolites important for varietal thiol will be evaluated in grapes and vineyard GIS map will be created for two winegrowing regions. Research will evaluate new yeast strains and their ability to release varietal and tropical aroma enhancement in white wines. The additional novelty of the project is the evaluation of various S compounds (elemental S, GSH, Cys, Met, H2S and yeast extracts) on varietal thiol release and content. The study of various S compounds addition on varietal thiol content in the must, will give new knowledge about metabolic processes involved in the production of important volatile sulfur compounds and new strategies in the pursuit of fermentation nutrients as a tool to adjust wine aroma. The project outcome will give now yeast strain possibilities and S-compounds management in varietal thiol management. This presents a challenge to the winemaker in order to modulate the concentrations of sulfur quality-determining compounds in wine in accordance with consumer preferences.
Significance for science
The research will intensify the knowledge of varietal thiol management in white wines. Since the research is very applicative based, we expect a way towards the improvement of varietal characteristics of white wines. Beside this, new analytical methods will be set up for the determination of elemental S. As elemental S is widely used in vine disease management against powdery mildew, setting up of analytical method will give new possibilities for further research in vineyard control and food safety. In Slovenia, there is no proper method yet to control elementary sulfur in fruits. Results will be presented in scientific articles and at various conferences. At least three scientific articles shall be published in publications with high impact factor. The vineyard map of secondary metabolites important for thiol aroma will be made for two winegrowing region (Slovenska Štajerska and Primorska-Istra). This will serve for better forecasting of new vineyards planting in the future. It will also characterize vineyards about their varietal thiol potential based on soil and climate characteristics. In climate change era, the knowledge of aroma compounds content in the grapes is very important.
Obtained results will allow oenologists to integrate new pre-fermentative and fermentative technologies in order to improve aromatic potential of Slovenian wines. Implementing new fermentation management in production of white wines will serve to improve the quality of white wines and to help wine producers (Vinakoper, P&F Jeruzalem Ormož) being more competitive on the pretentious market in the world. On the other hand, oenologists and wine producers will acquire new knowledge and scientific support which could help them producing target wine style. Students (Master, PhD) will be involved in project activities and results will be used in lectures and different symposium.
Significance for the country
The competitiveness of wines on the market is very high, therefore producers are forced to adapt the needs and demands of consumers. According to the consumer preferences, the trend of wine vinification is directed to fresh wines with a better expressed varietal aromatic. It is important for winegrowers to produce wines of different target styles. Knowledge and details in the optimisation and modulation of aromatic compounds, especially volatile thiols, are key in improving competitiveness on the global market.
Within the project, two main wine cellars in Slovenia (P&F Ormož and Vinakoper) and small wine producers will obtain important data about the content of secondary metabolites (thiols, glutathione precursors, etc.) in their vineyard, and information about soil composition and microclimate influences (so called ‘terroir’) on aromatic potential of their grapes.
In addition, the wine cellars will gain new knowledge on the use of starter cultures in the combinations of conventional (Saccharomyces) and non-conventional (non-Saccharomyces) yeasts for aromatic (volatile thiols) expression and the quality of white wines. The most suitable combinations of yeast will be selected from so called ‘yeast bank’ selection and best combinations will be tested and proposed to Slovenian winemakers. Research on the use of yeast nutrients, with an emphasis on sulfur-containing compounds will bring new opportunities for winemakers in modulating and improving the varietal aromatic.
