lecture 18: blending and sensory evaluation of table wines
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Lecture 18:
Blending and Sensory Evaluation of Table Wines
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Reading Assignment:
Text, Chapter 10 pages 415-426
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Blending Objectives
• Complexity within vintage
• Correct a deficiency or excess
• Freshen old wine
• Age young wine
• Fortification
• Amelioration
• As part of style
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Varietal Wine Labeling in California
• Vintage: 95% must be from that vintage• Varietal: 75% must be from that varietal• Viticultural appellation: 85% must be
from that growing region• “Produced and Bottled By”: must control
75% of the fruit• “Estate Bottled”: 100% must be from
that appellation controlled by the winery
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“Controlled by the Winery”
Do or direct all vineyard work- do not have to own all vineyards
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Factors to Consider When Choosing a Blend
• Acidity
• Residual sugar
• Alcohol
• Appellation
• Flavor
• Style
• What are the most critical components?
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The Blending Process
• Bench Tasting to “guesstimate” best blends
• Make trial blends in small scale
• Period of “marrying”: 3 weeks to 6 months depending upon style
• Re-evaluation of blends
• Determination of final blend
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Why Do Blends Need to “Marry”?
To determine if an unexpected problem develops over time
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Types of Unpredictable Changes with Blending
• Instability– Protein/polysaccharide haze– Microbial: bringing microbes and nutrients together– Tartrate: bringing tartrate and ions together
• Flavor changes – Unmasking– Masking– Creation of novel characters
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Unmasking
A character present in one of the wines becomes more noticeable in the blend
Dilution of a competing factor that prevents/limits detection
Character due to a combination of chemicals and the concentration of those components increases in the blend
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MaskingOne flavor is masked by another: seems
to disappear in the blend
Due to dilution
Due to competition for detection
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Novel Characters
Chemical reactants brought together resulting in new aromatic product
Chemicals brought together that are perceived as something other than the original aromas
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Linearity of Blending Traits
Some aromas are not linear with dilution– Below or above threshold of detection– Trait due to mixture of components– Matrix (acidity) effects
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Linear vs. Non-Linear Blending
Threshold of detection
Saturated detection
Linear Range
Concentration
Det
ectio
n re
spon
se
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Computation of Blend Ratios
• “Pearson’s Square”
• By algebraic equation
• Graphical method for multiple components
• Software program
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Computation of Blending Ratios: Pearson’s Square
a
b
m
b-m
m-a
a,b represent concentration in wine
m represents desired concentration
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Pearson’s Square: Example
Wine “A” is 11% ethanol, Wine “B” is 15 %. The desired final ethanol concentration is 12%.
11%
15%
12%
15-12 = 3
12-11 = 1
A blend of 3 parts of A (11%) to 1 part of B (15%) will yield the desired ethanol concentration.
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Algebraic Equation
VA + VB = 1 VA = 1 - VB
11VA + 15VB = 12(VA + VB )
11( 1- VB ) + 15VB = 12((1 – VB) + VB)
11 – 11VB + 15VB = 12 – 12VB + 12VB
4VB = 1
VB = 1/4 = 1 part of VB to 3 parts of VA
Can solve multiple simultaneous equations if needed
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Always Check Calculations
3 parts of 11 = 33
1 part of 15 = 15
__________________
4 parts total = 48
48/4 = 12
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Dealing with Multiple Wines
A = 11%; B=15%; C=14%; D=13% and want 12% ethanol for final blend
12 12 12
11
15
11 11
1314
3(11):1(15) 2(11):1(14) 1(11):1(13)
Totals: 1(15):1(14):1(13):6(11)
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Common Problems with Pearson’s Square
• Forgetting to have lowest concentration in upper left
• Both wines exceed or are below the desired concentration
• Ignoring negative numbers
13
15
12
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Dealing with Multiple Components
Frequently, blend decisions are made considering multiple wines and multiple components (sugar, ethanol, acidity, etc.). In this case, graphical methods can be used to estimate the best overall blend. However, the ideal value of each component might not be attainable.
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The Sensory Evaluation of Table Wines
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It is important to use scientifically sound procedures for the evaluation of wines.
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Wine Attributes for Analysis
• Appearance
• Odor
• Taste
• Aroma
• Flavor
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Sensory Evaluation of Wines
• Descriptive analysis
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Descriptive Analysis
• Goal: to describe the aroma and flavor profile of a wine
• Using panel discussion decide upon flavor/aroma characters of wine
• Train tasters using standards (wine spiked with characters of wine)
• Blind tasting to determine if characters can be reproducibly recognized in wines
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Sensory Evaluation of Wines
• Descriptive analysis
• Difference tests
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Difference Tests
• Use trained judges
• Determine if two wines are reproducibly selected as different
• Requires statistical analysis
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Difference Tests for Wine Evaluation
• Triangle
• Duo-Trio
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The Triangle Test
Tasters are presented with three wines and asked to determine which wine is different from the other two.
184
359 672
184 = wine A
672 = wine A
359 = wine B
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The Triangle Test
A statistical analysis can then be used to determine if the number of times wine 359 was selected as different is significant or not.
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Difference Tests for Wine Evaluation
• Triangle
• Duo-Trio
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The Duo-Trio Test
Tasters are provided with a reference and two sample wines. They are asked to determine which sample wine is DIFFERENT from the reference.
R 184 352
R = 352 = Wine B
186 = Wine A
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The Duo-Trio Test
A statistical analysis can then be used to determine if the number of times wine 184 was selected as different is significant or not.
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Sensory Evaluation of Wines
• Descriptive analysis
• Difference tests
• Intensity rating
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Intensity Rating Scales
Important to train judges to know what a term is and what value they will assign to specific intensities in wines
Can then convert rating into a numerical score for statistical evaluation
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Intensity Scale
Least Most
Astringent Astringent
1 2 3 4 5 6 7 8 9 10
Taster then rates the wine for the desired trait
1 2 3 4 5 6 7 8 9 10
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Sensory Evaluation of Wines
• Descriptive analysis
• Difference tests
• Intensity rating
• Hedonic tests
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Hedonic Evaluation
Uses untrained consumers
Evaluates whether a taster likes a particular wine or not
Can use an overall evaluation scale
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Overall Evaluation ScaleAssign wine to one of the following categories:
1. Like intensely
2. Like moderately
3. Like slightly
4. Neither like nor dislike
5. Dislike slightly
6. Dislike moderately
7. Dislike intensely
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Profiling Consumer Definitions of Quality:
Preference Mapping J. Yegge & A. C. Noble
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Profiling Consumer Preferences
• Over 100 consumers
• 10 different Chardonnay wines
• External (packaging) and Internal (wine) factors evaluated
• Cluster analysis to look for groupings of individuals
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1. Do wines differ?
Difference Tests
2. How do they differ?
Descriptive Analysis
Time Intensity Methods
3. Which are liked? Preference Tests with Target Consumers
PREF-MAP
Flavors of preferred wines?
Consumer Definitions of Quality
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0
2
4
6
8butter
oak
caramel
spice
vanilla
caramel taste
astingencysour
sweet
apple taste
citrus
peach/apricot
floral
Wine B
Wine G
Wine D
Wine C
Yegge & Noble 2001
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Cluster 1
Cluster 2
Cluster 3
Cluster 4
Cluster 5
A1 A2
B
D
G
I CJ
F
H
E
Internal Internal Preference Map: Preference Map: ClustersClusters Fruitier
the better!
Oakier the better
Yegge & Noble 2001
Optimizers
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The Big Question:
Can Preference be divorced from Can Preference be divorced from Quality?Quality?
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Selection of Type of Sensory Analysis
• What are you trying to determine?
• Judge/taster fatigue
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This concludes the section on Post-Fermentation processing of wines.