Autochthonous yeasts: a microbiological tool to exalt the quality of the Apulian sparkling wine

The selection, characterisation and recruitment of autochthonous yeast strains to drive the alcoholic fermentation process is a highly researched practice because it allows the differentiation of the organoleptic properties of wines, assuring process standardisation, reducing fermentation times and improving the quality and safety of the final products [1, 2]. Sparkling wines are "special wines" obtained by secondary fermentation of the base wine. In the traditional method (Champenoise method), the re-fermentation takes place in the bottle after the addition to the base wine of the so-called tirage solution. This step, also known as prise de mousse, is followed by an aging period characterised by the release of compounds from the yeast cells that affect the organoleptic properties of the final product. The use of autochthonous yeasts as starter cultures for secondary fermentation is one of the recent innovations proposed to enhance and differentiate these wines' sensory quality [3,4]. Apulia is the second Italian wine-producing region, and its productive chain is now going through a qualitative evolution by implementing the employment of innovative approaches to exalt the peculiar properties of regional wines. This enhancement is also pointed out by the increasing production of sparkling wines by indigenous grape cultivars [4]. We have technologically characterised several autochthonous strains belonging to Saccharomyces cerevisiae species isolated in the Apulian region, firstly at the lab scale and, successively, tested in winery for both induce alcoholic fermentation in base wine and re-fermentation of white and rosè sparkling wines. For the first time, we evaluated the fermentative properties of selected yeast strains, through a non-targeted metabolomic approach based on the correlation between the volatolomic profile determined by GC-MS and the chemical profile obtained by HPLC-HRMS. Also, we highlighted the important role of yeasts to enhance not only the volatolomic profile but also the phenolic fraction of fermented wines. This confirms that the choice of an autochthonous strain positively modulate the chemistry of wine, with potential impact on the global organoleptic properties of the final sparkling wine. This is the first report on the use of autochthonous strains isolated in the Salento area (Apulia, Southern Italy) for the secondary fermentation to produce sparkling wine. For the first time, to the best of our knowledge, the use of autochthonous strains in sparkling wine has been tested using an integrated non-target metabolomic approach