Enological Suitability of Indigenous Yeast Strains for 'Verdejo' Wine Production

The use of indigenous yeasts for the production of wines is a tool to defend the typicity of a particular region. The selection of appropriate indigenous yeasts ensures the maintenance of oenological characteristics by simulating spontaneous alcoholic fermentation (AF) while avoiding the risks of stuck or sluggish fermentations. In this study, autochthonous yeasts from Verdejo grape juice (Appellation of Origin Rueda) were selected, identified, and characterized to exploit the characteristics of the 'terroir'. The fermentation capacity of seven strains was studied individually at the laboratory scale. The most suitable strains (Saccharomyces cerevisiae: Sacch 1, Sacch 2, Sacch 4, and Sacch 6) and Sacch 6 co-inoculated with Metschnikowia pulcherrima were characterized at the pilot scale. The fermentation kinetics, bioproduct release, volatile composition, and sensory profile of the wines were evaluated. Significant differences were found, especially in the aroma profile. In particular, Sacch 6 and Sacch 6 co-inoculated with M. pulcherrima produced higher amounts of ethyl esters and acetates and lower amounts of higher alcohols than the spontaneous AF. Wines inoculated with indigenous yeasts had higher sensory scores for fruit aromas and overall rating. The selection of indigenous yeasts improved the aroma of Verdejo wines and could contribute to determining the wine typicity of the wine region.