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Management of Grape and Wine Aroma and Flavor
International Symposium of Food Science and Technology
Bruce W. ZoeckleinHead, Enology-Grape Chemistry Group
Department of Food Science & TechnologyVirginia Tech
Blacksburg, VA USA
www.vtwines.info
Virginia
Major varieties:Chardonnay, Cabernet Sauvignon, Cabernet Franc,Merlot
Other varieties:Mourvedre, Sauvignon Blanc, Riesling,Viognier, Norton, Petit Manseng, Tannat, Petit Verdot
UNITED STATES OF AMERICA
NORTHEAST
Virginia Tech
Enology-Grape Chemistry Group
Virginia Tech
Enology-Grape Chemistry Group
Virginia Tech
Enology-Grape Chemistry Group
Source: Pretorius and Høj (2005)
, aroma
Source: Pretorius and Høj (2005)
Presentation Goals
• Defining the goals of aroma / flavor management and research
• Aroma / flavor as quality attributes• Management of aroma and flavor in
grapes and wines• Eye towards the future
Virginia Tech
Enology-Grape Chemistry Group
Wine Quality
HARMONYFINESSE
COMPLEXITYBALANCE
COLOR QUALITY
PERSONALITY OF THE GRAPEVARIETAL CHARACTER
CLEANLINESSABSENCE OF UNPLEASANT AROMAS AND FLAVORS
Virginia Tech
Wine/Enology-Grape Chemistry Group
Steadman (1992)
Source: Swiegers et al. (2005)
Source: Francis et al. (2005)
Volatile Compounds in Wine
directly from the grapefrom non-volatile grape precursors yeast and bacterial metabolismoak wood extractionchemical reactions upon storage
Virginia Tech
Wine/Enology-Grape Chemistry Group
Vineyard Management
• Heat• Light• Soil• Soil moisture
Steadman (1992)
Free and Bound Aroma/Flavor
FreeGrape-
Derived Volatiles
Sugar-bound Components
Odorless/FlavorlessNonvolatile
Glycosides
MaturityProcessingAging
Virginia Tech
Wine/Enology-Grape Chemistry Group
Aliphatic residues
Monoterpenes
Sesquiterpenes
Norisoprenoids
Phenols /Anthocyanins
OH
O-
HOCH3O
OH
O-
HO
HOCH2
β-apiofuranosyl
O
OCH3
HOHO
OH
O-
O
HO
CH2
OH
OHO
O
R
R
α-L-arabinofuranosyl
α-L-rhamnopyranosyl
Glycoside StructureBound Aroma/Flavor Components Virginia Tech
Enology-Grape Chemistry Group
source: M. Naeker and V.M. Cabalda-Crane
D-glucose Aglycones
Wine Flavor IntensityStrongly correlates with Grape Glycosides, but not always with Sugar
Steadman (1992)
Vineyard Parameters Impacting Glycosides and Free Volatiles
• Crop load• Light interception• Heat• Soil• Soil moisture• Maturity
Virginia Tech
Enology-Grape Chemistry Group
Chardonnay Crop Load Total Glycosides vs. Brix
1
1.3
1.6
1.9
11.5 13.5 15.5 17.5 19.5 21.5 23.5Degrees Brix
Tota
l Gly
cosi
des
umol
/g f
wtx
10
4.4 TPA 7.5 TPA 8.4 TPA
Virginia Tech
Enology-Grape Chemistry Group
Source: Zoecklein, 1998
Changes in Total Glycoside Concentration for Chardonnay
Grapes
0
0.5
1
1.5
2
2.5
18.5 19.5 20.5 21.5 22.5 23.5 24.5
Degrees Brix
Gly
cosi
des
(um
ol/g
f w
t x10
)
4.4 TPA 7.5 TPA 8.4 TPA
R2=0.83
R2=0.86R2=0.99
Virginia Tech
Enology-Grape Chemistry Group
Source: Zoecklein, 1998
Geneva Double Curtain (GDC)
– Divided canopy– Shoots trained down
Smart-Dyson (SD)
– Shoots trained up and down
Vertical Shoot Positioned (VSP)
– Common system in Virginia– Shoots trained up
0
10
20
30
40
50
60
Total Glycosides
GDCSD-UpSD-Down
-25-20-15-10
-505
101520
Phenol-freeGlycosides
GDCSD-UpSD-Down
a
b
c
VSPb
b
c
a
%
VSPd
%
2002 Berry Total Glycosides and Phenol-Free Glycosides
Percent difference relative to VSP
Wine Volatile Organic Compound Analysis
Virginia Tech
Enology-Grape Chemistry Group
Volatile Analysis of Juice 2003
0
10
20
30
40
50
60
Linalool α-Terpineol β-Damascenone n-Hexanol
VSPSD-UPSD-DownGDC
1
2
3
4
(mg/L)(μg/L)
ab b b
aab
ab
ba
abb
ba abbc c
abc Different letters denote significant difference (p≤0.05) of treatment means.
PCA Sensory Analysis of2003 Viognier Aroma
Sulfur / Vegetative
Fruity
Overall intensity
SD-Down
SD-Up
GDC
VSP
PCA Sensory Analysis of2003 Viognier Flavor
CarbonationAlcohol burn
Astringent
SourSweet
Harsh/fusel oil
Brown spice
Woody Sulfur
Fruity/sweet aromatic
SD-Down
SD-Up
GDC
VSP
Targets for Improvement Focus of Research
Grape QualityImproving quality factors
Improved color development
Ripening-related processes and signals
Improved sugar accumulation and transport
Phloem loading and unloading
Improved production of glycosidically-bound aroma/flavor precursors
Improved engustment, the liberation of free volatiles
Source: In part, Pretorius and Høj (2005)
Steadman (1992)
Steadman (1992)
Steadman (1992)
Source: Swiegers et al. (2005)
Free and Bound Wine Aroma/Flavor
FreeFermentation
and Aging-Derived Volatiles
FreeGrape-Derived
Volatiles
Sugar-bound Components
Odorless/FlavorlessNonvolatile
Glycosides
ProcessingAging
Virginia Tech
Wine/Enology-Grape Chemistry Group
Yeast Fermentation
Source: Swiegers et al. (2005)
Targets for Improvement Focus of Research
Improving fermentation performance
Improved resilience and stress tolerance
Improved efficiency of sugar utilisation
Improved efficiency of nitrogen assimilation
Improved ethanol tolerance
Increased tolerance to antimicrobial compounds
Reduced foam formation
Stress response, sterol, glycogen and trehalose
Hexose transporters, hexosekinases
Improved utilisation of less efficient N sources
Sterol formation, membrane ATPase activity
Resistance to killer toxins, sulfur dioxide, agrichemicals, heavy metals
Cell-surface proteinsSource: Pretorius and Høj (2005)
Source: Swiegers et al. (2005)
Effect of Fermentation on the Relative Concentration of Wine Volatiles
0
0.5
1
1.5
2
2.5
3
Ethyl Esters Acetate Esters HigherAlcohols
Losses due toentrainment with CO2After fermentation
Aro
ma
Uni
ts
Source: Adapted from Simpson and Miller (1984)
Effect of Capture and Return on Chardonnay Wines, Control vs Treatment
* Significance of t-test at p ≤ 0.05.
Cut Grass
Honey
Butterscotch
Butter
Banana
Nail Polish Remover
Floral/fruity
Apple
Cherry
Pear
Grape
Citrus
ControlTreatment
Virginia Tech
Enology-Grape Chemistry Group
*
Source: Zoecklein et al. 2001
* indicates significance at p < 0.05, Student’s t-test.
Post-Bottling Heat Treatment:Total Glycosides and Phenol-Free Glycosides of
Heat Treated Cabernet Sauvignon
0
200
400
600
800
1000
1200
1400
Total Glycosides Phenol-Free Glycosides
GG
(um
ol/L
)
Control
Treatment*
*
Source: Mansfield and Zoecklein, 2003
Targets for Improvement Focus of Research
Improving wine sensory attributes
Enhanced liberation of grape volatiles
Enhanced production and retention of desirable volatile esters
Optimised fusel oil production
Enhanced glycerol production
Bioadjustment of wine acidity
Optimisation of phenolics
Reduced sulfite and sulfide production
Release of volatile thiols
Glycosidases, glucanases, arabinofuranosidases
Esterases, alcohol acetyl transferases
Amino acid metabolism
Glycerol metabolism
Maloethanolic and malolacticfermentation, lactic acid production
Phenolic acid metabolism
Sulfur metabolism, hydrogen sulfide formation
Lyases
Source: in part, Pretorius and Høj (2005)
Source: Swiegers et al. (2005)
Targets for Improvement Focus of Research
Improving wine wholesomeness
Increased production of resveratrol
Reduced formation of ethyl carbamate
Reduced formation of biogenic amines
Decreased levels of alcohol
Decreased levels of pesticides / fungicides
Stilbene synthesis and β-glucosidases
Amino acid metabolism, urea formation
Bacteriolytic enzymes, bacteriocins
Carbon flux, glycerol metabolism and glucose oxidation
Source: Adapted, in part, from Pretorius and Høj (2005)
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