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)

www.vtwines.info