STUDY OF THE INOCULATION TIME OF Lactobacillus plantarum IN COMBINATION WITH DIFFERENT YEASTS

The interactions among different microbial populations have interested the wine microbiology community with the final aim of understanding the impact on wines' quality. The main interaction occurs between yeast Saccharomyces cerevisiae, yeast non-Saccharomyces spp. and lactic acid bacteria (LAB) [1]. In last years, there is a special interest in the study of non-Saccharomyces yeasts as they are responsible for much of the aromatic complexity and its presence improves the final organoleptic characteristics of the wine [2]. Interactions between yeasts and LAB have been studied always combining S. cerevisiae with some LAB and in almost all cases Oenococcus oeni, but poor evidences have been reported for interactions between non-Saccharomyces and LAB in the wine environment. Lactobacillus plantarum selected strains have been receiving increasing attention as starter cultures for malolactic fermentation in wine. With the aim to design of mixed culture to perform AF and MLF simultaneously in a short period of time, with complex organoleptic properties, and also to control the indigenous microbiota and to protect wine against spoilage microorganisms, in this work we report the evaluation of the best inoculation time of L. plantarum strains (both commercial and autochthonous Apulian strains) in combination with autochthonous S. cerevisiae strains and non-Saccharomyces (Hanseniaspora sp. and Candida sp.). 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 non-Saccharomyces, were co-inoculated and L. plantarum 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 "Sviluppo di approcci microbiologici innovativi per il miglioramento della qualità di vini tipici regionali (NEWine)".