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 outermostlayer of the celi wall notably varies for composition and structure. Parietalmannoproteins can contain negative charges that modify electrostatic and ionicinteraction with wine components, giving good reason to propose a specific selectionof wine yeasts, based on type and amount of parietal mannoproteins. Phenoliccompounds interact with yeast mannoproteins; they can diminish the total polyphenolindex of wine by interaction between anthocyanins and celi walls. Wine yeastinfluences concentration and composition of phenolic compounds in wine, above aliby adsorbing them on celi wall. Remarkable correlations between yeast used forwinemaking and phenolic compounds in wine were reported, demonstrating thatstrain behaviour can modify chromatic properties, phenolic profile and antioxidantpower of wine. The parietal adsorption of grape pigments during winemaking hasimportant effects for wine quality, because of the amount of pigment removed. Yeastcan also interact with wine colour producing anthocyanin-beta-D-glucosidase, pyruvicacid, acetaldehyde, and polysaccharides. Wine yeasts can also selectively removeochratoxin A (OTA) during winemaking because they possess the ability to adsorbOTA. Based on parietal adsorption activity, a specific selection of yeasts will beperformed to protect wine colour and phenolic compounds responsible for antioxidantactivity of wines but to remove OTA. Genomic strategies for genetic improvement ofstrains will be used to obtain a further enhancement of the adsorption/non-adsorptionactivity of wine yeasts. The production of new strains through sexual recombinationcan be achieved through two different approaches: gametes derived from cropsindividuai spores of parental strains gametes or directly from the parental strains. Theinheritable nature of the adsorption of wine colour was recently analysed on thedescendants derived fram three wine strains of S. cerevisiae. Investigation of theprageny demonstrated that the adsorption of wine colour is a polygenic inheritablequantitative traits loci, partially and interdependently correlated to colour and phenoliccontent of wines. This work was supported by PRIN 2007 "Wine strain improvementstrategies to enhance red wine safety based on parietal adsorption activity"