Strategia di selezione di nuovi ceppi autoctoni di Saccharomyces cerevisiae: caso studio Sangiovese dell’area del Chianti.

Within the context of an investigation aimed at obtaining Saccharomyces cerevisiae strains with oenological characteristics able to confer good expression of organoleptic characteristics and highlight the typicity of wines obtained from grapes cultivated in zones of particular viticultural-oenological interest, a bank of wine yeast strains has been created. One thousand two hundred S. cerevisiae strains, isolated from musts of Sangiovese grapes in spontaneous fermentation, have been preliminarily characterised for the presence of some oenological traits (prerequisites) necessary for a strain to be considered suitable for vinification. Subsequently, the strains which gave interesting results in the screening phase were studied to highlight the presence of quality traits (production of secondary compounds of fermentation, production of macromolecule-polysaccharides of parietal origin and hydrolytic enzymes). Tests conducted under real vinification conditions allowed the individualization of some strains possessing good oenological aptitude, together with the ability to dominate, throughout alcoholic fermentation, the indigenous flora of the musts and to favour the onset of malolactic fermentation. The results showed that the presence of suitable traits for a correct and regular execution of alcoholic fermentation of the grape must is a rather rare quality in natural S. cerevisiae populations. Moreover, the presence of unconventional traits cannot always be associated with traditional technological characters, thus the selection of new strains is an area of research that must constantly be updated.