New oenological practice to promote non-Saccharomyces species of interest: saturating grape juice with carbon dioxide

Non- Saccharomyces yeast species, naturally found in grape must, may impact wine quality positively or negatively. In this study, a mixture of five non- Saccharomyces species ( Torulaspora delbrueckii , Metschnikowia spp., Starmerella bacillaris (formerly called Candida zemplinina) , Hanseniaspora uvarum , Pichia kluyveri ), mimicking the composition of the natural non- Saccharomyces community found in grape must, was used for alcoholic fermentation. The impact of CO 2 saturation of the grape juice was studied first on this mixture alone, and then in the presence of Saccharomyces cerevisiae . Two isogenic strains of this species were used: the first with a short and the second a long fermentation lag phase. This study demonstrated that saturating grape juice with CO 2 had interesting potential as an oenological technique, inhibiting undesirable species ( S. bacillaris and H. uvarum ) and stimulating non- Saccharomyces of interest ( T. delbrueckii and P. kluyveri ). This stimulating effect was particularly marked when CO 2 saturation was associated with the presence of S. cerevisiae with long fermentation lag phase. The direct consequence of this association was an enhancement of 3-SH levels in the resulting wine.