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8/13/2019 Wisconsin Grape Quality
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What is Quality?
Nobody knows!
Easy to define what quality is NOT
Hard to define what it IS
Grapes are at the highest potential
qualitywinemakers maintain or detractfrom that potential
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Most important factor:
How does the wine TASTE?
Nothing else matters.
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ECON 101
Supply
Demand
Supply vs. Demand
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ECON 101
Supply
Demand
Commodity Market
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ECON 101
Supply
Demand
Specialty Market
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Communication:
-Its up to you!-Push the winemaker
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Goals Today
Investigate attributes worth talking about
Understand the importance of theseattributes
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Some basics
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Grape Ripening
Time
Amount Acid
Sugar
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Grape Ripening
Time
Amount Acid
Sugar
1
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Grape Ripening
Time
Amount Acid
Sugar
1 2
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Ripeness Effects
Flavor
Acid
pH
TA
Color
Hue
Intensity
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Ripening and Flavor
Time
Amount Acid
Sugar
1 2
Flavorchange!
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Acid Expression
Paradox of acid expression:
Titratable acidity: grams per Liter
pH: inverse logarithmic representation of thehydrogen proton concentration
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Acid Expression
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Ripening and Hue
Low pH, 20-25% High pH, 10%Flavylium State Quinoidal State
Most Anthocyanins colorless at wine pH
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Ripening and Color Intensity
Rim Variation
I wanted to see this in a lab
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Wine A: High Color Intensity
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Wine B: Low Color Intensity
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Ripening and Color Intensity
Wine A; Hue = .6; Intensity = 3
Wine B; Hue = .9; Intensity = 1.8
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White Wine Tasting:
Investigating Effect of TA
Dont finish the samples!
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Monitoring Fruit
Its a sample!
Striving for even ripening:
Dormant season pruning
Shoot positioning
Green harvest
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Hungry?
Want to use this plate?
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Sanitation vs. Sterilization
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Sulfur Citric Sanitation
Requires:
200 ppm Sulfur; 2-3 tablespoons
< 3.0 pH; couple scoops
Buying Potassium Metabisulfite
Efficacy
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Hungry?
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Sulfur Dioxide Additions
Inhibits enzymatic oxidation
Polyphenoloxidase
Laccase
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Sulfur Dioxide Additions
Calculating sulfur dioxide
Based on JUICE YIELD
Average 150 gallons juice/ton
Clean Fruit 30 ppm = 30 grams (1.06 oz.)
Rotten Fruit 75 ppm = 74 grams (2.65 oz.)
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Hungry?
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Lady Bugs
Green, peas, peanuts, gross mushrooms
Identification threshold is at PPT
1 trillion seconds = 31,546 years
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Spray Records
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Cellar Handling
Chaptalization
$.75/pound C&H
$9.39/T ($.06/gal.) to raise 1 Brix
Amelioration
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Red Wine Tasting:
Investigating Effect of TA
Dont finish the samples!
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Correlation
Comparison of 2 independent data sets
R value explains variability
Low r = no relationship
High r = possible relationship (r > 85%)
R = .65 means 65% of variability is accountedfor
CAUSATION is not implied
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CorrelationShark Attacks
Ice Cream Sales
R = .24R squared = .0576
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CorrelationShark Attacks
Ice Cream Sales
R = .89R squared = .79
Not Causal!
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Searching for a correlation
A model to predict quality wines
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Frontenac Project
R = 66.5%
R = 60.6%
Percentage
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Frontenac Project
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Frontenac Project
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Frontenac Project
r = 68.3%r = 60 %r = 47%r = 63.5%r = 58.5%
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Frontenac Project
r = 78.8%
DescriptorFrequency
Intensity Rating
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Red Wine Tasting:
Investigating Effect of TA onTannin Perception
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Obviously, quality indicators ofwine will be multivariate
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Suppleness Index
Suppleness aka richness
Relationship of alcohol, tannin, and acid
Review:
Alcohol measured in percent
Acid measured in grams/liter
In France its calculated as Sulfuric Acid and not
Tartaric Acid
Tannin measured in g/L
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Suppleness Index
Alcohol(Acid + Tannin) = Suppleness
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Suppleness Index
The equation:
ETOH% - (T.A. + Tannin) = Suppleness
> 5 = supple wine
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Suppleness Index
Cabernet examples:
Wine 1:
12% Alc - (3.6 TA + 1.8 Tannin) = 6.6
Supple
Wine 2:
10.5% Alc(4.2 TA + 2.4 Tannin) = 3.9Not Supple
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Suppleness Index
Frontenac examples:
Sample 743: 12.73%(7.45 TA + .5 Tannin)= 5.78
Sample 291: 11.5%(6.6TA + .5 Tannin) =4.4
Sample 238: 11.9%(16.2TA + .5 Tannin)= -4.8
Correlation: Suppleness and Numeric
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Correlation: Suppleness and NumericAward:
r = .52; 52% of variability accounted for
Amelioration?!
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FrontenacOrdered by SupplenessSample Supple (.5 tan.) Award Award Num.
743 5.78 Gold 7.11
272 5.67 Silver 5.26
291 5.40 Silver 5.18
787 5.03 Silver 4.58662 4.97 Silver 5.26
588 4.78 Silver 5.38
781 4.77 No Medal 1.93
374 4.40 Silver 4.93
453 4.20 Gold 6.83
61 1.83 Bronze 3.03
238 -3.82 No Medal 2.86
1. No2. B-
3. B4. B+5. S-6. S
7. S+8. G
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Suppleness: Key Lessons
Acid reinforces bitter/astringent flavors
High acid and high tannin are not good
High alcohol and low acid required forelevated tannin levels
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Suppleness in Perspective:
Developed by Peynaud and Gayon
Bordeaux wine production in the 50s and
60s
High suppleness = riper fruit
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Who is Hungry?
because lunch is in 15 minutes!
Paul Gospodarczyk
Des Moines Area Community College
ptgospodarczyk@dmacc.edu
paul@todayswineprofessional.com
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