1. VEN124 Section V Post-Fermentation Processing

2. Lecture 14: Clarification and Filtration and the Compositional Adjustment of Wine

3. Reading Assignment: Text, Chapter 7 pages 289-307

4. The 5 Goals of Post-Fermentation Operations: 1.Clarity 2.Compositional adjustment 3.Stability 4.Style 5.Packaging

5. The 5 Goals of Post-Fermentation Operations: 1. CLARITY

6. Clarification GOAL: to eliminate existing cloudiness

7. Clarification Options Natural settling/racking Centrifugation Filtration

8. Natural Settling/Racking Decanting wine off of solids May add a settling aid to “tighten” lees Volume loss high Gentle process

9. Settling and Racking Settled Lees Racking Valve

10. Centrifugation: Types Desludging Decanting

11. Centrifugation: Function Removal of particles using centrifugal force Can be adjusted to remove larger or smaller particles

12. Centrifugation: Problems Aeration Cost –Modified atmosphere –Low temperature

13. Filtration Types of filtration processes Kinds of filter units

14. Filtration Processes Sieve Adsorption

15. Sieve Particles larger than pore size are retained by filter

16. Adsorption Particles adhere to matrix

17. Adsorption and Sieving

18. Kinds of Filter Units Depth-bed

19. Depth-Bed Filtration Filter matrix mixed with wine Filter matrix builds as wine is filtered through coated screen Constantly laying down new matrix with wine

20. Depth-Bed Filtration Screen Wine Wine + Matrix Pre-coat

21. Depth-Bed Filtration Diatomaceous earth; cellulose; perlite Cost effective Minimal clogging “Rough” filtration: sieving action is minimal Principle of “torturous path” for particles to travel

22. The “Torturous Path”

23. Kinds of Filter Units Depth-bed Pad

24. Pad Filtration Filter matrix is a preformed sheet or pad Sieving as well as adsorption Pads come in a variety of porosities, but pore size is heterogeneous Flow of wine perpendicular to pad “Dead end” filtration

25. Pad Filtration Wine Filtered wine

26. Kinds of Filter Units Depth-bed Pad Membrane

27. Membrane Filtration Like pad filtration, but uses a membrane Fixed pore size Sieving as well as adsorption Clog easily “Finishing” filtration

28. Membrane Filtration WineMembrane Filtered Wine XX XX XX XX XX

29. Kinds of Filter Units Depth-bed Pad Membrane Cross-flow

30. Cross-Flow Filtration Same porosities as membrane filtration Wine flows across matrix, not through it Wine retentate can be re-circulated Back flux can be used to clear membrane Does not clog that easily

31. Cross-Flow Filtration Wine Retentate Filtered Wine

32. Order of Filtration: Rough Before Finishing XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

33. The Question: Does filtration impact wine flavor and aroma?

34. The Belief: Filtration removes flavor and aroma compounds and is therefore undesirable. “Unfiltered” wines are more complex than filtered.

35. The Facts: Several studies have shown that expert tasters are not able to recognize filtered versus unfiltered control wine. Unfiltered wine allows continued microbial activity, which may explain differences perceived in unfiltered wines in general.

36. The 5 Goals of Post-Fermentation Operations: 2. COMPOSITIONAL ADJUSTMENT

37. Compositional Adjustment Acidity

38. To increase acid add: –Malate –Tartrate –Citrate To decrease acid add: –Calcium carbonate To remove volatile acidity: –Reverse osmosis

39. Compositional Adjustment Acidity Sugar level

40. Sugar Level Add juice concentrate Arrest fermentation –Addition of ethanol Fortified wine Fortified juice –Temperature shock

41. Compositional Adjustment Acidity Sugar level Ethanol level

42. Evaporative removal with return/replacement of co-stripped volatiles Reverse osmosis followed by adjustment of flavors/aromas

43. Compositional Adjustment Acidity Sugar level Ethanol level Tannin removal

44. Tannin Removal Time of aging: to allow polymerization to occur Ultrafiltration: 500-2000 mw cut-off

45. Compositional Adjustment Acidity Sugar level Ethanol level Tannin removal Sulfide/mercaptan removal

46. Sulfide/Mercaptan Removal Copper sulfate (formation of CuS  ) –H 2 S –Some thiols Copper sulfate + SO 2 + ascorbate –Disulfide removal –VERY SLOW