Wisconsin Grape Quality

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

[email protected]

[email protected]

Documents

Wisconsin Grape Quality