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Non-Saccharomyces Strains in Wine

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. Native Fermentations Deliberate Inoculation. Native Fermentations. Native Fermentations.

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Non-Saccharomyces Strains in Wine

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  1. Non-Saccharomyces Strains in Wine Linda F. Bisson Department of Viticulture and Enology University of California, Davis

  2. Role of Non-Saccharomyces Yeast in Wine Aroma • Native Fermentations • Deliberate Inoculation

  3. Native Fermentations

  4. Native Fermentations • Rely on microbial flora of grapes and wineries to conduct fermentation • No deliberate inoculation with commercial strains • May be inoculated from an existing native fermentation

  5. Native Fermentations • Diversity of yeast and bacterial species • Numbers and persistence impacted by grape/must/juice treatments • Numbers and persistence impacted by winery Saccharomyces flora

  6. The Most Important Variables • Condition of the fruit: level of rot • Time of harvest • Processing conditions • Oxygen exposure • Solids level • Juice/Must amendments • pH • Sulfite/antimicrobial addition • Temperature

  7. Yeast Native Flora • Show strong impacts of maturity • Show differences by climate • Show seasonal effects • Show differences by varietal • Show site effects • More strongly influenced by insect trafficking

  8. The Most Common Yeasts of the Berry Surface Yeast % of Total Isolates Kloeckera apiculata/ Hanseniaspora uvarum 65-80 Candida species 5-10 Issatchenkia 5-10 Metschnikowia 5-10 Pichia species 10-20 Basidiomycetes 10-20

  9. Saccharomyces • Not often isolated from vineyards • Depends upon practice of dumping yeast lees in vineyard • Depends upon level of rot • Is present but in very low numbers, one out of ten million yeast isolates • Even at these low numbers will dominate wine fermentations

  10. Impacts of Wild Yeast Flora • Ester production • Terpene production • Hydrolytic enzyme production (release of bound flavor precursors) • Carotenoid degradation? • Source of stress for Saccharomyces

  11. The Common Wild Yeasts • Ethyl Acetate Producers: • Kloeckera/Hanseniaspora • Candida stellata • Ester Producers: • Candida: other species • Metschnikowia • Issatchenkia • Pichia species

  12. Non-Saccharomyces Inoculants

  13. Non-Saccharomyces Inoculants • Mixtures of Saccharomyces and non-Saccharomyces strains • Separate inoculations • Combined in one packet • Provide positive benefits of complexity of wild fermentations with a low risk of off-characters • Kluyveromyces thermotolerans • Torulaspora delbrueckii

  14. Hybrid Strains

  15. Hybrid Commercial Strains • Forced mating of two closely related but different species • Parental strain often sterile but combines properties of both parental strains in the hybrid

  16. Second Flight: Hybrids and Non-Saccharomyces Strains • Glass 1: Native (no inoculation) • Glass 2: DV10 (control S. cerevisiae) • Glass 3: Cross Evolution (hybrid) • Glass 4: NT116 (hybrid) • Glass 5: Rhythm (60Sc:40Kt) • Glass 6: Melody (60Sc:20Kt:20Td)

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