Sabrina Voce_Universidad de Udine (Italia) 

Yeast derivatives are additives widely used in winemaking for different purposes. Currently, their production process is not well standardized, and their chemical composition is often not specifically tailored for winemaking applications. Thermal treatment, enzyme addition and autolysis are the most common methods used for their production, whereas non-Saccharomyces spp. strains have been recently authorized by International Organization of Vine and Wine (OIV) for obtaining yeast derivatives. In this study, Torulaspora delbrueckii and Saccharomyces cerevisiae were used as starting microorganisms for producing yeast derivatives, whereas ultrasounds and high hydrostatic pressure were applied as potential alternatives for inducing lysis or inactivating yeasts. T. delbruecki showed a good aptitude for producing yeast derivatives, particularly concerning polysaccharide content (up to 74 mg/g) and radical scavenging activity (44.7 µmol/g), compared to the conventional S. cerevisiae (62 mg/g and 39.9 µmol/g, respectively). In terms of chemical composition, the derivatives obtained by ultrasounds were similar to those resulting from enzyme addition, mainly characterized by soluble compounds – proteins, amino acids and polysaccharides – whereas the application of high hydrostatic pressure allowed the preservation of the antioxidant properties of both soluble and insoluble fractions of the products, together with a low odor impact. The effect of the addition of yeast derivatives on the chemical composition and volatile profile of a white wine was also tested after two and six months of aging, using sulfur dioxide as control. At practical level, no differences in color evolution and oxidizability potential were observed between control samples and wines added with yeast derivatives after six months of aging. A similar trend in polysaccharides release was observed in most samples, regardless of the strain used as starting microorganism. On the other hand, the volatile profile of wines was affected by yeast derivatives addition, mainly related to the treatment performed during the production process, rather than the initial yeast strain. Wines added with derivatives obtained by ultrasound and enzyme addition showed the most characterized volatile profile. Conversely, wines added with derivatives obtained by thermal treatment and, to a minor extent, by high hydrostatic pressure showed a tendential, lower concentration of wine volatile compounds. The chemical composition of yeast derivatives may be managed using specific yeast strains or applying the most suitable processing technologies, allowing the production of additives with enhanced antioxidant properties, higher content of polysaccharides or low odor impact. Consequently, this might allow to reduce the amount of sulfur dioxide, to accelerate the aging time, to modulate the wine aroma profile with a potential reduction of times and costs of the overall winemaking process.

Sabrina Voce, Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine;
Anna Bortolini, Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine;
Lara Tat, Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine;
Andrea Natolino, Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine;
Piergiorgio Comuzzo, Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine.