Wine Flavor 101B Introduction to Native Fermentations

1. Wine Flavor 101B Introduction to Native Fermentations

2. Impact of Winemaking Technologies • Impact on composition • When to use • Unintended consequences • Value added versus cost (value may be important even if it is just to marketing) • What to do when things go wrong

3. Impact on Composition

4. Impact of Native Fermentation on Composition • Chemical complexity derived from the biological activities of a consortium of microorganisms • Slower fermentations: less heat, less loss of volatile compounds • Enhanced mouth feel and finish • Better stability post-fermentation

5. Types of Native Fermentations • Vineyard Microbiota? • Winery Microbiota? • Both?

6. Types of Native Fermentations • Native non-Saccharomyces organisms? • Yeast? • Bacteria? • Both? • Native Saccharomyces? • All of the above?

7. Types of Native Fermentations • “True” native microbiota • Manipulated native microbiota • Partial native microbiota • Inoculated native microbiota

8. “True” Native Microbiota • No inoculation: autochthonous microbiota • No use of additions or chemical or physical changes to manipulate microbial populations

9. Source of Native Microbiota • Vineyard • Winery surfaces

10. Source of Native Microbiota • Vineyard site effects • Winery sanitation practices • Winery production practices

11. Vineyard Site Effects • Humidity • Average temperature • Soil and vine microbiota • Disease pressure • Insect vectors • Adjacencies • Vineyard practices • Number and timing of drive throughs • Irrigation • Fertilizer use and application practices

12. Winery Sanitation • Types of agents used • How used (how often, how rigorous, before and after use) • Goals for reduction in microbial counts • Are all surfaces approached with the same target microbe goals?

13. Winery Production Practices • Crushing operation • Cold soaks • Cold settling • Hot cap extraction • Temperature of fermentation • Type of fermentation vessel • Oxygen exposure • Pressing regimen

14. Even if you do not intend to manipulate the microbiota, you are by default

15. Microbial Requirements for Growth • Permissive Conditions • Absence of Non-Permissive Conditions

16. Permissive Growth Requirements • Nutrients • Macronutrients • Micronutrients • Allowable pH range • Allowable osmotic range: “water activity” • Allowable temperature range

17. Non-Permissive Conditions • Lack of requirements: competition • Presence of inhibitory conditions • Chemical inhibitor • Physical environment inhibition

18. Microorganisms differ in what defines permissive and non-permissive conditions

19. Microbial Ecosystems • Are dynamic • Depend upon relative numbers • Depend upon relative metabolic activities • Depend upon type of growth: surface (biofilm) or free floating (planktonic) • Impacted by subtle changes in the environment

20. Manipulated Native Microbiota • No inoculation • Use of sulfite • Use of nutrient additions • Use of temperature to alter competitiveness • Use of physical means to remove/alter microbial populations

21. Partial Native Microbiota Fermentation • No inoculation at onset of enabling microbial activity • Inoculation occurs at some point in process • Point in process: • Early to initiate fermentation • After native yeasts have started • Near end to assure completion • Inoculant may be: • Commercial strain • Active fermentation

22. Inoculated Native Microbiota Fermentation • Inoculate with non-Saccharomyces organisms • Simultaneously with Saccharomyces • Inoculate sequentially with Saccharomyces

23. When to use

24. Issues in Use of Native Fermentations • Unpredictability • Microbiota present • Risk factors for spoilage • Risk factors for arrest of fermentation

25. Risk Factors for Spoilage • Unsound fruit • High microbial loads in winery/deficient sanitation practices • Insect invasion of vineyard • Issues with fruit composition • Very slow start of fermentation

26. Risk Factors for Arrest of Fermentation • Unsound fruit • High and unchecked inhibitory microbial populations • Nutrient availability decreased • Creating a non-permissive environment for fermentation

27. When Not to Use • When risk factors are high: Unsound fruit, fruit track record is “difficult to ferment” • When you cannot blend it out if there is a problem • Insurance policy (10% of volume inoculated as a precaution) is not possible

28. Unintended consequences

29. Unintended Consequences • Get some characters/impacts you want and some you do not (changes in flavor versus loss of color) • May be addressed by manipulating microbiota • Very long fermentations that result in too much oxygen exposure or lead to greater loss of grape impact compounds (style too “microbial”)

30. Today’s Program

31. So What Did We Do? • We started with unsound fruit . . .

32. Sulfite Native Trial • Goal: Assess impact of sulfite additions on resulting wine composition following native fermentation. • Used: Chardonnay that had pervasive low cluster percentage rot issues • Sulfite range: 0, 15, 25, 50, 100, 200 ug/L

33. Sulfite Range • Lower levels inhibit bacteria but not yeast • Higher levels inhibit within yeast and select for more resistant organisms

34. What Did We Expect to See? • Problems at the low end of sulfite use • At some level of sulfite the inhibitory microbes would be inhibited and fermentation progression would improve • Wines would differ in things other than just residual sugar • (and we were not disappointed)

35. Use of pH to Manipulate Microbiotoa • Goal: When starting with unsound fruit, can pH alteration be a useful tool to manipulate microbiota? • Used: a red blend (to get the right starting pH) • pH range: 3.3, 3.5, 3.7, 3.9

36. What Did We Expect to See? • There would be microbial differences • There would be unintended consequences

37. Sulfites Tasting • Chardonnay: pH 3.6; 22.4 Brix; TA: 5.76 g/L

40. Sulfite Tasting • Glass 1: Native, 0, no sulfites during fermentation • Glass 2: Native, 15 ppm sulfite • Glass 3: EC1118, 15 ppm sulfite • Glass 4: Native, 50 ppm sulfite • Glass 5: EC1118, 50 ppm sulfite • Glass 6: Native, 100 ppm sulfite

41. pH Tasting • Glass 1: pH 3.3 • Glass 2: pH 3.5 • Glass 3: pH 3.7 (control) • Glass 4: pH 3.9