Lecture 3:

1. Lecture 3: The Harvesting Decision: Viticulture from the Winemaker’s Perspective

2. Reading Assignment: Text, Chapter 2, pages 52-64

3. The Winemaker’s Perspective • Grapes must be harvested at the ideal time for the style of wine desired to be made • Characters of the finished wine will be largely dictated by the composition of the fruit at harvest • Goal: to have the ideal composition at time of harvest

4. Berry Ripening: Acids Veraison Malate Tartrate Concentration Time

5. Berry Ripening: Sugars Dehydration Concentration Synthesis stops Net synthesis Time

6. Berry Ripening: Arginine Thought to signal deterioration of fruit Concentration Time

7. Berry Ripening: Evolution of berry flavors in red grapes Vegetation Herbaceous Unripe Fruit Red Fruit Black Fruit Jam

8. Vegetation: Plant matter Herbaceous: Straw, Vegetable Unripe Fruit: Green apple, Citrus rind Red Fruit: Cherry, Strawberry, Raspberry Black Fruit: Plum, Black Cherry, Blackberry Jam: Prune, Date, Raisin

9. Stems: Unripe: Green = vegetal, leafy Ripe: Brown = resinous wood, spices: clove, pepper, cinnamon Over-ripe: Brittle Brown: Dried leaf, tea, herbal

10. Decision to Harvest • Berry compositional factors • Berry physical traits • Non-berry factors

11. Berry Compositional Factors • Sugar: ranges from 19-26 Brix • Depends upon style of wine • Maturity of flavors • 1.7% sugar  1% ethanol

12. Berry Compositional Factors • Sugar • pH: 3.0-3.8 • Affects solubility of tartrates and proteins • Affects microbial populations

13. Berry Compositional Factors • Sugars • pH • Acids: • Contribute Sourness and Tartness • Titratable Acidity: Whites (0.7-0.9 g/L) Reds (0.6-0.8 g/L)

14. Wine Acidity Total Acidity: Sum of anionic species Titratable Acidity: Amount of base needed to reach a specific end point Fixed Acidity: Not distillable Volatile Acidity: Distillable (acetic acid)

15. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Brix/TA = 30 or less, depending . . . • 22 Brix/ 0.8 TA= 27.5 • (Brix)(pH)2 = 220-260, depending . . . • (22 Brix)(3.2)2 = 225.3

16. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Ratio of malate to tartrate

17. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Ratio of malate to tartrate • Arginine levels

18. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Ratio of malate to tartrate • Arginine levels • Taste

19. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Arginine • Ratio of malate to tartrate • Taste • Phenolics/Anthocyanin levels

20. Berry Compositional Factors • Sugar • pH • Acids • Balance of sugar and acidity • Arginine levels • Ratio of malate to tartrate • Taste • Phenolics/Anthocyanin levels • Terpene content

21. Terpene content • Measure terpenes directly • Measure free/bound terpenes • Measure all bound aromatic precursors (GG) analysis

22. Berry/Cluster Physical Traits • Berry firmness and deformability • Seed characteristics • Color • Integrity • Stem characteristics • Color • Integrity

23. Non-Berry Factors • Environmental factors

24. Environmental Factors • Rain • Humidity • Temperature • Disease Pressure

25. Non-Berry Factors • Environmental Factors • Tank capacity/limitation

26. Non-Berry Factors • Environmental Factors • Tank capacity/limitation • Labor availability

27. Non-Berry Factors • Environmental Factors • Tank capacity/limitation • Labor availability • Fruit availability

28. Which factors are most important in the decision to harvest will vary with the wine style, the winemaker, and the vintage

29. Sampling the Vineyard • Need to obtain an unbiased representation of the entire crop • How uniform is the vineyard? • Soil • Climate • Elevation • How uniform are vineyard treatments? • Sampling protocol should lead to a statistically significant evaluation

30. Types of Sampling • Berry: 100-200 berries randomly picked • Cluster: 20-50 clusters also randomly chosen • Cluster/Berry: remove all berries from clusters; randomly select 200 berry lots • Vine: select typical vine and sample all clusters

31. Berry sampling is most robust statistically but more susceptible to harvester bias than cluster or vine sampling

32. Harvesting Conditions

33. Once the decision has been made that it is time to harvest, the winemaker/vineyard manager must then decide how the fruit is to be harvested

34. Harvesting Options • Temperature • Machine • Hand

35. Temperature of Harvest • Lower temperature: • Less flavor loss • Less extraction from skins • Less microbial activity • Elevated temperature: • More extraction • Initiate fermentation earlier

36. Machine Harvesting • Faster • Cheaper • Can be done day or night • Less gentle • Mixture of “good” and “bad” clusters • More “MOG” (material other than grapes) • Berries can be crushed • Juice loss • Oxidation • Microbial Growth

37. Hand Harvesting • Slower • More labor intensive • More expensive • More selective of clusters • Less MOG • Lower yield

38. This concludes the first section on viticulture for winemakers. The next section will cover juice and must treatments and processing decisions.