1. Wine Flavor 101 Common Wine Taints Napa Valley Vintners January 13, 2012 UC Davis WELCOME TO:

2. Overview of Today’s Topics Linda F. Bisson Department of Viticulture and Enology University of California, Davis

3. Introduction to VENsource and Wine Flavor 101  VENsource: Viticulture and ENology System for OUtreach Research Communication and Extension  Comprehensive on-line and in-person programs aimed at maintaining the competitive edge of the wine and grape industries and in facilitating transfer of newly discovered information

4. VENsource On-Line Enology Access web site: Content rich Problem solving guides Aids for training Best practices analyses Discussion forum

5. Wine Flavor 101: Series of programs defining the impact of decision making on wine flavor

6. Wine Flavor 101: The Need  Advances in wine chemistry: dissection of wine composition and sensory perception  Microbe genomics enabling greater understanding as well as ability to control metabolite effects  Grape genome: ability to target viticultural practices to enhance or diminish specific characters

7. Wine Flavor 101: The Important Questions  What are the key impact compounds?  What are the key matrix effects?  Now that we can manipulate characters, what do we want to manipulate?  What are the best ways to modify characters? (Vineyard? Fermentation? Aging? Blending?)

8. Wine Flavor 101: The Realities  Personal preferences and style differ  Interpretation and detection of components differ  Interactive effects are profound  Intensive efforts underway internationally to optimize and target flavor outcomes

9. Wine Flavor 101: The Competitive Advantage  State-of-the-Art Winery  New Research Facilities  Enhanced Research Capability  Optimized Working Relationship with Industry

10. Wine Off-Characters  Off-colors  Off-flavors  Hazes/cloudiness  Sediment/precipitates

11. Source of Off-Characters  Vineyard  Unsound fruit  Fermentation microbes  Oxidation/reduction reactions  Spoilage microbes

12. Off-Characters  Same off-character may come from different sources (acetaldehyde)  Some off-characters arise only in specific chemical/microbial environments  Compound(s) responsible for some taints unknown  Best course of action: not getting them in the first place!

13. Microbial Off-Characters  Pre-fermentation  During fermentation  Post-fermentation

14. Microbial Off-Characters  Pre-fermentation  During fermentation  Post-fermentation

15. Pre-Fermentation Off-Characters  Derive from the metabolic activities of non- Saccharomyces yeasts and bacteria  Increased impact with rot  Increased impact with hang time  Juice and must processing can encourage pre-fermentation character formation

16. Pre-Fermentation Processing  Lower temperatures: favor non- Saccharomyces yeasts  Low, no or late sulfite additions: favor both non-Saccharomyces yeasts and bacteria  Warm temperatures: favor bacteria  Oxygen exposure: favors both non- Saccharomyces yeasts and bacteria

17. Pre-Fermentation Processing  Lower temperatures: favor non- Saccharomyces yeasts –Cold soak/maceration (reds) –Cold settling (whites) –See bloom of Hanseniaspora/Kloeckera

18. Pre-Fermentation Processing  Low, no or late sulfite additions: favor both non-Saccharomyces yeasts and bacteria –Favors growth of both wild lactics and acetic acid bacteria –Favors growth of non-Saccharomyces yeasts

19. Pre-Fermentation Processing  Warm temperatures: favor bacteria –Cap management strategies –Refrigeration capacity

20. Pre-Fermentation Processing  Oxygen exposure: favors both non- Saccharomyces yeasts and bacteria –All organisms benefit from presence of oxygen –Obligate aerobes not inhibited

21. Types of Pre-Fermentation Characters  Esters  Acids _______________________________  Higher alcohols  S-compounds  Aldehydes

22. Microbial Off-Characters  Pre-fermentation  During fermentation  Post-fermentation

23. Fermentation Off-Characters  Esters  S-compounds ___________________________________  Higher alcohols  Acetaldehyde  Higher aldehydes  Volatile acids

24. Fermentation Off-Characters  Influenced by yeast strain  Impacted by growth conditions  Affected by juice composition

25. Fermentation Off-Characters Influenced by yeast strain –Different strains vary ten-fold or more in compound production within dynamic range of odor detection –Strains dominate fermentation with differing efficiencies

26. Fermentation Off-Characters Impacted by growth conditions –Volatilization of compounds »Temperature »Head space –Nutrient availability »Nitrogen »Micronutrients »Oxygen –Microbial competition »Sulfite use »Inoculation practices

27. Fermentation Off-Characters Affected by juice composition –Availability of precursors –pH –Presence of stressors »High sugar/high ethanol »Previous microbial history

28. Today’s Program  Fermentation Off-Characters: the esters  Lactic Acid Bacteria Taints  Brettanomyces  Sulfur Taints