Biodiversity of autochthonous Saccharomyces cerevisiae from specific Apulian vineyard and their exploitation to produce sparkling wines

Sparkling wines should be defined as an effervescent wine, containing a relevant concentration of CO2 (about 3-7 atmosphere of pressure in the bottle). Usually sparkling wines may be produced by two methods, traditional method (also called méthode champenoise) and charmat method. they involves, respectively, a re-fermentation in the bottle or in hermetically-sealed tanks.The traditional method involves two fermentations steps: primary fermentation and secondary fermentation. During the first step grape juice is transformed into base wine, while the second one is an in-bottle fermentation of a base wine with tirage solution (saccharose, yeasts, grape must or wine, and bentonite) that led to the sparkling wine. Then second fermentation is followed by an aging period in which the wine is in contact with dead yeast (about 9-12 months). Starter cultures selected for sparkling wine production must satisfy several characteristics, in particular considering that re-fermentation is carried out in hostile environment (elevated ethanol content, low pH, increasing CO2...). Starter cultures should have other important characteristics, such as autolysis, killer phenotype and flocculation. Autochthonous starter cultures might be well adapted to specific environmental conditions and might allow to obtain wines with typical organoleptic properties. In this context, the present study investigated the use of select autochthonous resources for sparkling wine production. We evaluated the intraspecific biodiversity of about 200 Saccharomyces cerevisiae autochthonous strains isolated from Apulian spontaneous fermentation. One representative strain from each of the 16 genetic clusters was subjected to i) polyphasic technological characterization at lab scale and, successively, ii) assessment in winery for both induce alcoholic fermentation in base wine and re-fermentation of sparkling wine. Research was supported by the Apulian Region Project "Innovazioni di processo e di prodotto nel comparto dei vini spumanti da vitigni autoctoni pugliesi" (IProViSP).