Selection of Saccharomyces yeasts for the production of polyphenol-enriched wine.

Consumer interest in the close correlation between nutrition and health has helped promote intense research into bioactive compounds in foods. The polyphenols in wine, in addition to being important in determining its organoleptic characteristics, are considered to be primarily responsible for the beneficial effects this beverage promotes on human health. The concentration of polyphenolic substances in grape must is high, but during winemaking, their total content is substantially reduced (by more than 50 percent) by adsorption onto yeast wall polymers and subsequent lees separation. This issue can be addressed by using Saccharomyces cerevisiae strains with a lower tendency to adsorb polyphenolic compounds.The S. cerevisiae strains under study were identified from those contained in the CNR ISPA microbial collection. Specifically, 136 different strains were evaluated by laboratory-scale fermentation analysis.The results obtained showed that all strains decreased the concentration of polyphenolic compounds and, consequently, the antioxidant power. The best strains, i.e., those that differed in their lower ability to adsorb polyphenols, were selected and characterized during the various phases of the study. By processing the data obtained at the end of the different experimental phases, we were able to identify four strains, based on their qualitative performance. In fact, using the aforementioned strains, the wines obtained are found to have a high concentration of total polyphenols and an implemented antioxidant capacity, hold optimal aromatic properties, and have very low levels of volatile acidity and undesirable metabolites.Taken together, the scientific results described above emphasize the relevance of the development and industrial application of innovative biotechnological approaches in order to enhance the presence of healthful molecules in wine, thus improving "functional parameters" resulting in improved quality of the final wine.