STUDY OF THE INOCULATION TIME OF APULIAN AUTOCHTHONOUS Oenococcus oeni IN A MULTI-STRAIN STARTER

The winemaking process includes two traditional steps performed by microorganisms, alcoholic fermentation (AF) and malolactic fermentation (MLF). The AF is essential; sugars from grape must are converted into ethanol. This fermentation is carried out by yeast, mainly by Saccharomyces cerevisiae, however is not the only yeast involved in the process. A few specific non-Saccharomyces species, as Hanseniaspora uvarum have been proved to positively modify the wine chemical composition, especially contribute to the sensory characteristics of wines [1]. Interactions between different microbial populations present in grape must are interesting from the point of view of their impact on the final quality of the wine. The main interaction occurs among Saccharomyces spp. yeasts, non-Saccharomyces yeasts, and lactic acid bacteria (LAB) [2]. In the light of the rising request for autochthonous starters tailored for given 'terroir'[3], the objective of this work was to select the best inoculation time of autochthonous of Oenococcus oeni strains in combination with two S. cerevisiae strains and one H. uvarum strain isolated from Apulian wines. Direct interactions were also investigated monitoring cell viability on specific solid culture media. Microvinifications were performed using must from Apulian autochthonous grape varieties. Both, yeasts S. cerevisiae and H. uvarum, were co-inoculated and O. oeni strains were co-inoculated or sequentially inoculated during AF, when ethanol content was 2%, 4%, 6%, 8%, 10% or 12% (v/v). Ethanol formation, malic acid consumption and cell viability were monitored during the vinifications. This research was supported by the Apulian Region Project cod. QCBRAJ6 "Biotecnologie degli alimenti per l'innovazione e la competitività delle principali filiere regionali: estensione della conservabilità e aspetti funzionali - BIOTECA."