NonSaccharomyces Strains in Wine Linda F Bisson Department
Non-Saccharomyces Strains in Wine Linda F. Bisson Department of Viticulture and Enology University of California, Davis
Role of Non-Saccharomyces Yeast in Wine Aroma ØNative Fermentations ØDeliberate Inoculation
NATIVE FERMENTATIONS
Native Fermentations ØRely on microbial flora of grapes and wineries to conduct fermentation ØNo deliberate inoculation with commercial strains ØMay be inoculated from an existing native fermentation
Native Fermentations ØDiversity of yeast and bacterial species ØNumbers and persistence impacted by grape/must/juice treatments ØNumbers and persistence impacted by winery Saccharomyces flora
The Most Important Variables ØCondition of the fruit: level of rot ØTime of harvest ØProcessing conditions – Oxygen exposure – Solids level ØJuice/Must amendments Øp. H ØSulfite/antimicrobial addition ØTemperature
Yeast Native Flora ØShow strong impacts of maturity ØShow differences by climate ØShow seasonal effects ØShow differences by varietal ØShow site effects ØMore strongly influenced by insect trafficking
The Most Common Yeasts of the Berry Surface Yeast % of Total Isolates Kloeckera apiculata/ Hanseniaspora uvarum Candida species 5 -10 Issatchenkia 5 -10 Metschnikowia 5 -10 Pichia species 10 -20 Basidiomycetes 10 -20 65 -80
Saccharomyces ØNot often isolated from vineyards ØDepends upon practice of dumping yeast lees in vineyard ØDepends upon level of rot ØIs present but in very low numbers, one out of ten million yeast isolates ØEven at these low numbers will dominate wine fermentations
Impacts of Wild Yeast Flora ØEster production ØTerpene production ØHydrolytic enzyme production (release of bound flavor precursors) ØCarotenoid degradation? ØSource of stress for Saccharomyces
The Common Wild Yeasts ØEthyl Acetate Producers: – Kloeckera/Hanseniaspora – Candida stellata ØEster Producers: – Candida: other species – Metschnikowia – Issatchenkia – Pichia species
NON-SACCHAROMYCES INOCULANTS
Non-Saccharomyces Inoculants ØMixtures of Saccharomyces and non. Saccharomyces strains – Separate inoculations – Combined in one packet ØProvide positive benefits of complexity of wild fermentations with a low risk of offcharacters ØKluyveromyces thermotolerans ØTorulaspora delbrueckii
HYBRID STRAINS
Hybrid Commercial Strains ØForced mating of two closely related but different species ØParental strain often sterile but combines properties of both parental strains in the hybrid
Second Flight: Hybrids and Non. Saccharomyces Strains ØGlass 1: Native (no inoculation) ØGlass 2: DV 10 (control S. cerevisiae) ØGlass 3: Cross Evolution (hybrid) ØGlass 4: NT 116 (hybrid) ØGlass 5: Rhythm (60 Sc: 40 Kt) ØGlass 6: Melody (60 Sc: 20 Kt: 20 Td)
- Slides: 16