Wine strain improvement strategies to enhance red wine safety based on parietal adsorption activity

There is a great diversity among yeasts for parietal adsorption activity: the outermost layer of the cell wall notably varies for composition and structure. Parietal mannoproteins can contain negative charges that modify electrostatic and ionic interaction with wine components, giving good reason to propose a specific selection of wine yeasts, based on type and amount of parietal mannoproteins. Phenolic compounds interact with yeast mannoproteins; they can diminish the total polyphenol index of wine by interaction between anthocyanins and cell walls. Wine yeast influences concentration and composition of phenolic compounds in wine, above all by adsorbing them on cell wall. Remarkable correlations between yeast used for winemaking and phenolic compounds in wine were reported, demonstrating that strain behaviour can modify chromatic properties, phenolic profile and antioxidant power of wine. The parietal adsorption of grape pigments during winemaking has important effects for wine quality, because of the amount of pigment removed. Yeast can also interact with wine colour producing anthocyanin-beta-D-glucosidase, pyruvic acid, acetaldehyde, and polysaccharides. Wine yeasts can also selectively remove ochratoxin A (OTA) during winemaking because they possess the ability to adsorb OTA. Based on parietal adsorption activity, a specific selection of yeasts will be performed to protect wine colour and phenolic compounds responsible for antioxidant activity of wines but to remove OTA. Genomic strategies for genetic improvement of strains will be used to obtain a further enhancement of the adsorption/non-adsorption activity of wine yeasts. The production of new strains through sexual recombination can be achieved through two different approaches: gametes derived from crops individual spores of parental strains gametes or directly from the parental strains. The inheritable nature of the adsorption of wine colour was recently analysed on the descendants derived from three wine strains of S. cerevisiae. Investigation of the progeny demonstrated that the adsorption of wine colour is a polygenic inheritable quantitative traits loci, partially and interdependently correlated to colour and phenolic content of wines.