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

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

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

Berry Ripening: Acids Time Concentration Malate Tartrate Veraison

Berry Ripening: Sugars Time Concentration Net synthesis Dehydration Synthesis stops

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

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

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

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

Decision to Harvest Berry compositional factors Berry physical traits Non-berry factors

Berry Compositional Factors Sugar: ranges from Brix –Depends upon style of wine –Maturity of flavors –1.7% sugar  1% ethanol

Berry Compositional Factors Sugar pH: –Affects solubility of tartrates and proteins –Affects microbial populations

Berry Compositional Factors Sugars pH Acids: –Contribute Sourness and Tartness –Titratable Acidity: Whites ( g/L) Reds ( g/L)

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)

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

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

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

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

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

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

Measure terpenes directly Measure free/bound terpenes Measure all bound aromatic precursors (GG) analysis

Berry/Cluster Physical Traits Berry firmness and deformability Seed characteristics –Color –Integrity Stem characteristics –Color –Integrity

Non-Berry Factors Environmental factors

Environmental Factors Rain Humidity Temperature Disease Pressure

Non-Berry Factors Environmental Factors Tank capacity/limitation

Non-Berry Factors Environmental Factors Tank capacity/limitation Labor availability

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

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

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

Types of Sampling Berry: berries randomly picked Cluster: clusters also randomly chosen Cluster/Berry: remove all berries from clusters; randomly select 200 berry lots Vine: select typical vine and sample all clusters

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

Harvesting Conditions

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

Harvesting Options Temperature Machine Hand

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

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

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

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