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 uvarum65-80 Candida species 5-10 Issatchenkia 5-10 Metschnikowia 5-10 Pichia species10-20 Basidiomycetes10-20

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)