Wine Flavor Chemistry

Flavor is the psychological interpretation of
the physiological response to a physical
stimulus

Milton Bailey, University of Missouri, 1986
WHAT CAUSES VEGY FLAVOR in WINE?
Wines from two vineyard sites
BUTTER
SCOTCH
9 0
Sites
VANILLA
12
13
Berry
Flav or
MINT
CLOVE
1 8 0
4
3
2
1
0
1
2
3
SOY
4
Berry
Aroma
0
Bell
Pepper
Bell Pepper
Aroma
2 7 0
Vegy
Flav or
2 -methoxy 3 isobutyl pyrazine (2 ppt)
Identified in Bell Peppers (1969)
Sensitive to light (1986)
Method for quantifying : (2003)
SENSORY PCA – 19 wines (1986)
Clove
6
SpicyF
5
Mint
4
Soy
3
Vegy
2
BerryF
1
VegyF
PC1(42.2%)
0
-4
-2
0
-1
-2
BellPepper
-3
2
PC2(28.7%)
-6
4
6
BerryF
Vanilla
Butterscotch
SOIL PCA
4
OM
3
RootDepth
CEC
Harden
2
pH
Texture
1
PC1 (26.4%)
-3
-2
-1
0
1
2
3
C:F
-1
Wt Fines
-2
-3
-4
PC2 (24.2%)
-4
SoilAge
0
Structure
4
%Gravel
PLS of Soil and Vineyard factors
versus Sensory
8
SoilinRootZone
6
WarmerClimate
%Gravel
4
%Clay
SoilpH
Structure
Rootstock
SpicyF
2
Soy
VegyF
Vegy
VineAge
0
-6
-4
0
-2
BellPepper
-2
H20HoldingCap.
2
Clove
Vanilla
6
4
Mint
Butterscotch
BerryF
SoilAge(older)
Berry
Year(younger)
-4
Noble and Elliot-Fiske, 1990
PC2(30%)
Bell
VegetativePepper
by mouth
Black
Pepper
Eucalyptus
Spicy
BandAid
Fruit by
mouth
Green
Bean
Soy
Vanilla
Berry
PC1(39%)
Heymann (1986) Descriptive Analysis of Cabernet sauvignon
Color-Hue
Acidity
Berry
Astringency
Spicy
Floral
Body
Vegetative
PC2(31%)
PC1(39%)
ColorIntensity
Earthy
Vanilla
Animal
Chemical
Sivertsen, et al.(1999). Classification of French red wines according
to geographical origin by of multivariate data analyses
25%
nutty
licorice
floral
body
37%
grassy
persistence
art. fruit
passionfruit
citrus
grapefruit
Fischer, et al. (1999) The impact of geographic origin, vintage and
wine estate on sensory properties of Vitis vinifera cv. Riesling
Fresh Mint
Eucalyptus
Bell
Pepper
Cedar
Canned
Veg
Blk Cherry
Cherry
Musty
Ethanol
Fresh Berry
Karen Hein, 2005
M-R
M-S
Mint
Bell-Pepper
M-B
BP-R
Bell Pepper1
BP-S
BP-B
C-B
Corn1
Corn
C-S
C-R
Base
Berry
Raspberry
Strawberry
CANONICAL VARIATE ANALYSIS OF SPIKED WINE SAMPLES
Cabernet sauvignon – differences too subtle to describe
Morrison and Noble, 1990. Am. J. Enol. Vitic.41: 193 - 200.
12 UP
Veg by Mouth
Astringent
12 LO
25B UP
Vegetal
6
5
4
3
2
1
0
Fruit by Mouth
25B LNE
Black Pepper
Rose
Chocolate
Berry
25B LSW
Vegy Saga
Fraction Light
Vigor
Bell Pepper Aroma
Pyrazine
20
2000
2001
MIBP (ng/L)
15
10
2
R =0.7385***
5
0
2
R =0.7007***
-5
10
15
20
25
30
Buds/Vine
35
40
45
50
A) Bell Pepper Aroma
Average Intensity Rating
8
6
2
R =0.5720***
4
2
2
R =0.3541*
0
Average Intensity Rating
8
0
2
4B) Vegetative
6
8 10
12 14
Aroma
16
18
20
10 12by 14
16
Flavor
Mouth
18
20
IBMP (ng/L)
2
R =3702*
6
4
2
R =0.6394***
2
Average Intensity Rating
0
8
0
2C) Vegetative
4
6
8
IBMP (ng/L)
2
R =0.2091 (0.1)
6
4
2
R =0.5064**
2000
2001
2
0
2
4
6
8
10
12
MIBP (ng/L)
14
16
18
20
Pruning:
Pruning affects yield much more than pruning weight. Pruning to more buds/vine
generally increases yield and decreases shoot length.
Pruning to higher yield can lead to delayed sugar accumulation (probably when leaf area / fruit
weight gets below 12 cm2 / gm), and at even higher yields decreased color in fruit, and in
extreme cases decreased budbreak and fruitfulness the following year. Pruning to two times
the standard crop load in Napa (4-bud spurs instead of 2-bud spurs) did not prevent ripening.
Pruning to higher yields resulted in less veggy, less astringent, and more fruity attributes in
Cabernet Sauvignon wines. And the veggy and astringent attributes were correlated with the
concentration of MIBP (methoxypyrazine) and tannins in the wines.
There were almost no significant differences in sensory attributes among wines made from
vines with different cluster thinning treatments.
Evaluation of 96 Bordeaux red
wines


IBMP is the contributor to vegetal aroma in
Cabernet sauvignon; Cabernet franc and
Sauvignon blanc
Compound only found in a minority of Merlot
Compounds released in white wines
Markers for great Sauvignon blanc
4-mercapto-4-methylpentan-2-one (4MMP) (also in Scheurebe)
0.8 ng/l*; range 0-40 -- box tree, broom flower; cat pee; conifer
4-mercapto-4-methylpentan-2-ol (4MMPOH) 55 ng/l*; range
0-150 -citrus zest; grapefruit
3-mercapto-3-methylbutan-1-ol (3MMB) 1,500 ng/l*; range 30-150 – cooked
leeks
3-mercaptohexan-1-ol (3MH) 60 ng/l*; range 200-5,000 – grapefruit;
passion fruit; passion fruit skin
3-mercaptohexylacetate (3MHA) (also in Merlot, Cabernet sauvignon) 4.2
ng/l*; range 0-500 – box tree; passion fruit; sweet sweaty
Aqueous 12% alcohol solution with 5g/l tartaric acid; pH 3.5 25 J, triangle; 50% correct
increases during fermentation as these potent thiols released from
their S-cysteine conjugate precursors
Thiols in other varieties

4MMP and A3MH (3-mercaptohexylacetate [box tree]):
 Impact on aromas of Colombard and Muscat d’Alsace wines
As well as on young wines from Petit manseng*
3MH
 Contributes passion fruit and grapefruit to Gewurtztraminer,
Riesling, Petit manseng and botrytized Semillon


*White variety, South West France – may be Albarino: floral fruity flavors, a
distinct lemon and fruit salad flavor & high acidity increasing popularity
in Languedoc & California
Tominaga et al. (2000) AJEV 51(2):178-182
Production, location and extraction of S-Cysteine
Conjugates


Moderate water stress favor S-cysteine conjugate (P-thiol)
formation; severe prolonged stress limits production
Location of P-thiolsdiffer as f(volatile thiol)
 P-4MMP and P-4MMPOH -- 80% in juice
P-3MH – 50:50 between juice and skin
Upto 19 hours skin contact
 Some ↑ in P-4MMP and P-4MMPOH (20% + 30%)
 50% ↑ in P-3MH (even more extracted if skin contact at
18C vs 10C)


Peyrot des Gachons, Catherine: Aroma Potential of Sauvignon blanc grapes, PhD Dissertation Bordeaux
Transformation of p-thiols into varietal aromas



Transformation % low (1 month after fermentation) – due to yeast
lyases

1.4% for P-4MMP; 3% for P-4MMPOH; 4.2% for P-3MH
Not much transformed? Or Lost? Or metabolized or unstable? –
do not yet know
Do know that P-thiol disappearance is correlated with thiol
appearance
Peyrot des Gachons, Catherine: Aroma Potential of Sauvignon blanc grapes, PhD Dissertation Bordeaux
Glycosides in Red varieties
Norisoprenoids/norterpenoids from carotenes
Beta-damascenone
Shiraz stalky, earthy, cigar, and tobacco aromas
black pepper aroma by GCO not id’d
Cabernet Sauvignon and Merlot dried fig, tobacco
and chocolate aromas
Zinfandel Preliminary studies: Not much
contribution
Juice glycoside hydrolysate
Napa Cabernet juice
glycoside hydrolysate
tobacco
floral
4
Base wine
3
2
apple
1
0
honey
dried fig
chocolate
n=14 judges x 2 reps
Skin glycoside hydrolysate
Napa Cabernet skin
glycoside hydrolysate
tobacco
4
floral 3
Base wine
apple
2
1
0
dried fig
honey
chocolate
PLS of Aroma attributes versus volatiles
Component 2
volatiles
honey
floral
dried fig
tobacc
o
chocolate
apple
Component 1
juices
skin extracts
Volatiles related to the honey attribute
Norisoprenoids:
Benzene derivatives:
•damascenone
•vanillin
•hydroxydamascone •acetovanillone
•dehydro ß ionone
•cinnamic acid
•TDN
•vitispirane
•actinidol
Others:
Monoterpenes:
•acetyl furan
•ocimenol
•ethyl decanoate
•furan linalool oxide •diethyl propanedioate
•an ene diol
PLS of Aroma attributes versus volatiles
honey
Component 2
floral
volatiles
juices
dried fig
tobacc
o
chocolate
skin extracts
apple
Component 1
Volatiles associated with dried fig/tobacco
Benzene derivatives:
•syringic acid
•ethyl syringate
•a methoxy phenol
Others:
•two unknowns
•heptanoic acid
•hexadecanoic acid
•2-Et-3-Me maleic anhydride
Monoterpenes:
•trimethyl vinyltetrahydropyran
•furan linalool oxide
Vineyard Variables:
Trellising or leaf removal increases light
< 2-methoxy 3 isobutyl pyrazine
> norisoprenoids
Maturity
How to assess pH, TA, °B?
Grape Must Evaluation (evaluate in < 1 hour)
Rinse and Crush grapes, add 20 ppm SO2
Homogenize skins/juice versus juice
Grape Berry Evaluation
FERMENTATION
Temperature:
Cool: retain more volatiles
Warmer: more esters but lose more (fruity)
low MW
Yeast strain:? Biggest issue is H2S production
“Natural” versus inoculation
Skin Contact Time/Cap Management
Increase K, pH, phenols, anthocyanins
Centrifuging?
AGING
Terpene glycosides hydrolyze, but terpenes interconvert
to less fruity forms
Vitaspirane and 1,1,6 trimethyl 1,2 dihydronaphthalene 
increase
Esters hydrolyze slowly: Acetate esters & higher MW
faster.
Acids esterify; pH; Tannins polymerize
Oxidation reactions
Oak Aging
Extraction of volatiles:
vanillin, eugenol, oak lactone
Extraction: phenols, acids, lignins, CHO
Oak aging continued
VARIABLES:
Source oak
(Am  Vanillin; Fr  Phenols, extract)
Sawn vs split
Air vs kiln drying Air  Vanillin; Kiln HMF
Air drying in cool vs hot area
Hot  Vanillin ,Oak lactone
Hot  vanilla, caramel, buttery
Steamed or bent over fire
Degree toasting
 Furfural,  Vanillin