Wine provenance: geo-climatic, microbiological or human construct? Example of Slovene blaufrankish wines

Background and Aims: The concept of terroir can be described as an interplay of geogenic and anthropogenic factors influencing the typicality and quality of a wine from a particular geographical area. The scientific approach to terroir and wine provenance is complex due to the many variables that can be combined in a variety of ways. This requires combining the work of several research groups with complementary expertise, which is what the proposed project offers. Objectives: The main objective is to understand and reveal the main drivers contributing to wine distinguishment between regions considering geo-climatic, microbiological and human variables. Therefore, several sub-objectives were set: i) identification of key compounds and sensory descriptors that are responsible for the differences between wines at the sub-regional and regional level by sensory and chemical analyses ii) to understand response of grapevine to environmental signals that results in changes of grape berry composition which translates in expression of provenance in wines iii) to determine regional differences between microbial populations from grapes to determine if there are specific microbial communities associated with vineyards in different regions and to assess whether there is a real quantifiable (chemical and sensorial) effect of local microflora on wine provenance. Methods: work was divided in work packages, one for each sub-objective. To address first sub-objective we will purchase around 100 Blaufränkisch wines that will be sensorially analysed. All the wines will be also chemically analysed for the set of volatiles (terpenoids, esters, C6 compounds) using gas chromatography-mass spectrometry (GC-MS), basic analyses such as ethanol content, titratable acidity (TA), pH and set of non-volatiles (anthocyanins, polypehenols and tannins). For the second sub-objective six vineyards in two regions will be selected and closely monitored for geogenic, climatic and physiological variables. At harvest small scale vinifications will be performed and wines sensorially analysed. Grapes and wines will analysed for content of esters, C6 compounds and terpenoids using GC-MS; polyphenols, tannins and colour related compounds will be analysed using liquid chromatography-mass spectrometry (LC-MS/MS) and spectrophotometric methods. To achieve the third sub-objective grape microbiological populations will be sequenced using short-amplicon high-throughput sequencing (HTS). Since the biggest limitation of HTS is inability to address a functional characterization of the microbial community and strain diversity remains hidden, the cultivation approach with focus on yeast community will be included to obtain yeast isolates. Yeast isolates will be used in lab scale fermentations of Blaufränkisch grapes to test their contribution to wine provenance under controlled conditions. Outputs: We will be able to associate sensory attributes with the concentrations of aroma compounds, non-volatile components and human interventions and to determine typicality of Slovene Blaufränkisch wines. With detailed vineyard monitoring we will identify geo-climatic variables that importantly influence grape chemical composition and are translated in a sensorial and chemical wine characteristic that allow separation of wines according to its provenance. Once these regional differences are identified, key microbes will be isolated in pure culture to assess their contributions to the unique terroir or wine style(s) of the region. Outcomes: Grape growers and wine makers empowered by new knowledge and understanding of wine provenance could use these results as a promotional tool, especially on international markets. Origin focused agricultural marketing contributes to social, economic and ecological sustainability of rural areas with the list of benefits for a broader society. Isolated yeast strains will provide a key resource for wineries to enhance the expression of regional terroir.