AUTOCHTHONOUS APULIAN YEASTS, PRIMARY FERMENTATION OF BASE WINE, AND RE-FERMENTATION OF SPARKLING APULIAN WINES

Sparkling wines contain high amount of CO2 and are the result of re-fermentation of a still wine, usually called base wine. Several ingredients, such as sucrose, selected yeasts, bentonite and some nutrients, are added to base wine in order to induce the re-fermentation. Then wines can be bottled, fermented and aged for a long period (about 9-12 months). These wines represents an important percentage of the high-quality wine market and have an important economic impact due to its high added value [1-2], justifying the increasing attention to product improvements. Modern biotechnologies can be used to improve quality of sparkling wines, and also to reduce their production time and cost. Starter cultures selected for sparkling wine production must satisfy several characteristics, in particular considering that re-fermentation is carried out in hostile environment due to several factors, such elevated ethanol content, low pH and increasing carbon dioxide pressure [3]. In addition starter cultures should have other important characteristics, such as autolysis (important for aging in close contact with lees) and flocculation (another important selection criterion that aim lees removal) [4]. Authochtonous starter cultures have an important rule on wine quality, because autochthonous yeasts i) might be well adapted to specific enviromental conditions and ii) might allow to obtain wines with typical organoleptic properties. In these context this study investigated the use of select autochthonous resources for sparkling wine production. We genetically characterized about 200 Saccharomyces cerevisiae autochthonous strains isolated from "Nero di Troia" spontaneous fermentation. After the evaluation of intraspecific diversity using interdelta analyis, we selected one represtative strain for each of the 15 genetic cluster. These strains were technological characterized at lab scale and, successively, tested in winery for both induce alcoholic fermentation in base wine and re-fermentation of sparkling wine. This research was supported by the Apulian Region Project "Innovazioni di processo e di prodotto nel comparto dei vini spumanti da vitigni autoctoni pugliesi" (IProViSP).