Estudio de nuevas levaduras Killer "Saccharomyces cerevisiae" y "Torulaspora delbrueckii" para elaborar vinos tranquilos y espumosos

Abstract

Two new types of wine killer yeasts with broad antifungal activity were analysed: Saccharomyces cerevisiae Klus and Torulaspora delbrueckii Kbarr. They killed all the previously known S. cerevisiae killer and sensitive strains, in addition to other non-Saccharomyces yeasts. Beta-glucan seems to be the cell wall receptor of the sensitive yeasts. The killer phenotype is encoded by a medium-size (1.3 to 1.7 kb) dsRNA virus, M, which seems to depend on a large-size 4.6 kb dsRNA virus, LA, for stable maintenance and replication. The ORF at the 5' region codes for a putative preprotoxin followed by an internal A-rich sequence and a 3'-end non-coding region containing identical sequence fragments to most M-virus, suggesting that all they are evolutionarily related. The initial and exclusive must inoculation with Torulaspora killer Kbarr-1 allowed its dominance during all or most of the fermentation, producing dry wines with different flavor profile, which were much more appreciated when they were very structured red wines. By contrast, T. delbrueckii showed less fermentation vigour and viability during sparkling wine making (high pressure and low temperature), and did not complete the second fermentation without the presence and cooperation of Saccharomyces. Co-inoculation with S. cerevisiae killer plus sensitive strains improved the foam characteristics and the organoleptic quality of sparkling wines (cava).