## 1 Introduction  
Wine complexity and sensory quality can be attributed to many flavour compounds from several sources and wine production practices, i.e., grape variety, viticulture, oenology, and climatic conditions [1; 2; 3]. These practices are known to influence the development and concentration of flavour compounds within the grape berry during and after ripening and throughout processing and organoleptic quality of the wine [4; 5; 6; 7]. The grapevine species _Vitis vinifera_ has between 5000 and 10,000 different varieties; however, only a fraction of the varieties have commercial significance for wine and table grape production [8; 9]. Though each grape variety has its unique characteristics, the wine producer has the ability to utilise agricultural practices and winemaking technologies to influence the chemical composition of the grape berry and the organoleptic profiles of the wines [1; 2; 10]. Viticultural and oenological practices are of great importance to the levels of flavour compounds in the grape berry whilst yeast strains used for fermentation influence the final wine organoleptic quality [11; 12; 13; 14]. [PERSON] et al. [11] demonstrated the association between viticultural and oenological factors and their effect on the final expression of Sauvignonblanc wines from New Zealand, particularly related to vineyard location, vineyard row orientation, and grape processing operation (hand vs. machine harvesting). [PERSON] et al. [15] found that the S-cysteineylated and S-glutathionylated thiol precursors increased with total soluble solids during grape ripening, in high-flavour cultivars, such as Sauvignon blanc, and in a moderate-flavour cultivar, such as Grechetto. No differences were observed in the precursor compounds related to berry ripening in a low-flavour cultivar such as Malaysia del Lazio. Moreover, they were the first to identify and quantify S-3-(4-methyl-4-sulfanyl-pentan2-ol)-glutathione in all three cultivars as a glutathione-conjugated precursor of 4-methyl-4-sulfanylpentan-2-ol (4 MSPOH). [PERSON] et al. [16] reported on the differences found in the aroma profiles of Brianna and Frontenac Gris (white grape cultivars) wines when harvested at different degrees of ripeness, which directly influenced the variation in key odour-active compounds for both cultivars. Fungal diseases, i.e., downy mildew and powdery mildew, are known to negatively affect the grapevine and the grape berry composition [17]. Therefore, fungicides are used as standard viticultural management practices to control such fungal growth but could influence the grape aroma compounds and wine quality [17; 18]. Research conducted by [PERSON] et al. [18] on Chenin blanc grapes treated with different chemical sprays, i.e., Methyl-1H-pyrazole carboxylic acid phenylethyl amide, boscalid, and penconazole, with an extract of _Gelania African_ highlighted that the different sprays affected wine yeast protein expression. This is important because yeast-derived proteins are needed to release certain wine-aroma-enhancing compounds (metabolites), particularly volatile thiols, during fermentation, therefore influencing the aroma profile of the wine [14; 19]. Differences in metabolite levels meant that the fungicide treatments affected the yeast's ability to express proteins, which influenced the wine's aroma and flavour [18]. Although fungi are generally associated with spoilage of wine grapes, _Botrytis cinerea_ (grey mould) causes noble rot under favourable conditions to produce bortylised wines [20; 21; 22; 23]. Previous studies found that wines made from bortylised grapes had significant amounts of volatile thiols, especially 3-SH, largely due to the concentration effect that _Botrytis_ has on the grape berries [21; 22; 23]. Moreover, grape growers and winemakers are continuously confronted with new challenges as climate change affects grape physiology and viticultural practices. These, in addition to advances in winemaking technologies, influence the development of varietal aroma and flavour metabolites in wines [24; 25].