Towards the prediction of wine outcomes from grape

compositional measures

Bob Dambergs, Paul Smith

WS42 18 July 2012

The Australian Wine

Research Institute

AWRI technology along the value chain

Working on the Value Chain from vineyard soil to point of sale, and beyond

The Australian Wine

Research Institute

Some basic wine parameters

• F/T SO2

• Heat and cold stability

• pH

• TA

• Alcohol

• Sugar

• VA

The Australian Wine

Research Institute

Classes of quality measures, based on process

• Grape metabolites directly extracted into wine

• Grape metabolites converted by mechanical processing

• Grape metabolites converted by yeast processing

• Grape metabolites converted by a combination of mechanical and yeast processing

The Australian Wine

Research Institute Grape metabolites directly extracted into wine

• Rotundone

• Methoxypyrazine

• C13 norisoprenoids

– Beta-ionone

(-)-Rotundone

• By GC-MS-O, rotundone was established as the principal aroma

impact compound for pepper aroma in grapes and wine.

• 20-25% of people can’t smell it

O

Wood, C.; Siebert, T. E.; Parker, M. et al. J. Agric. Food Chem. 2008, 56, 3738-3744 Siebert, T. E. et al. J. Agric. Food Chem. 2008, 56, 3745-3748

• We can now start to look at what influences rotundone levels

• A large survey of commercial wines was undertaken to guide us

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AWRI TR #180 (June 2009)

Rotundone in Australian wines

• Impact of viticulture on Rotundone?

Fruit exposure?

Leaf removal time?

Crop load?

Vine vegetative vigour?

rotundone

not detected

not detected

found in grape skins, leaves and stalks Increases during grape ripening

The Australian Wine

Research Institute Methoxypyrazines

• Concentration in wines depend on • berry maturity • climate • fruit exposure • skin contact during winemaking, pressing

• Green bean, capsicum, asparagus • IBMP easily extractable

– concentration in free-run wine is principally determined by that in the grapes, while it is relatively unaffected by vatting conditions.

• Cabernet sauvignon, merlot, sauvignon blanc, semillon (not in pinot grapes, shiraz, chard, riesling)

The Australian Wine

Research Institute

Wine aromas that are released or created from grape compounds (but a little help from yeast...)

• Terpenes;

– geraniol (skin), Linalool (throughout berry), Nerol (skin), alpha-terpineol

– Wine lactone

• C13 norisoprenoids

– Beta-Damascenone

• C-6 alcohols

The Australian Wine

Research Institute Free Terpenes

• Geraniol (skin) & Nerol (skin) – young wines

• Linalool (throughout berry) & alpha-terpineol – older wines

• Rose, geranium, floral

• Enzyme and acid releases the glycosylated precursor from grapes

The Australian Wine

Research Institute

Polyhydroxylated terpenes

• the polyhydoxylated monoterpenes make no direct contribution to the aroma although some of them are reactive and can easily rearrange during ferment to give pleasant and potent aromas;

• cis rose oxide – lychee, rose

• Wine lactone – coconut, lime

The Australian Wine

Research Institute

• Grape berry metabolism

• Carotenoid degradation

• Bound to sugars: released from glycoside precursors

• Diverse aroma properties as a class

– damascenone sweet, fruity, cooked apple,

– ionone raspberry, berry, violets

C13 Norisoprenoids

The Australian Wine

Research Institute

C13 Norisoprenoids during grape maturation

C6-alcohols

1-hexanol

cis-3-hexenol

• Fresh cut grassy aroma in wine

• enzymatic oxidation of grape fatty acids by lipoxygenases,

• solids in ferment

• Role in green flavour unclear

The Australian Wine

Research Institute

Wine aromas created by metabolic action of yeast

• Esters

• Alcohols

• 4-EP

• VA

The Australian Wine

Research Institute Esters

fatty acid ethyl esters, acetate esters • fruity aromas • isoamyl acetate (3-methyl butyl acetate) banana • ethyl hexanoate pineapple

• slower rate of fermentation, increase in esters – ie lower temp

• yeast strain • juice composition: amino acid pattern • undergo chemical hydrolysis/reaching chemical equilibrium with storage • varietal differences can be significant • Very significant in defining sensory profile of the wine • Fatty acid derivatives role in esters

The Australian Wine

Research Institute Higher Alcohols

• Yeast metabolism of amino acids and sugars. For e.g. Phenyl ethyl alcohol – from phenylalanine, (rose-like aroma)

• lsobutanol – Solvent, harsh

• Isoamyl alcohol – whiskey, malt, burnt

• 2-Phenylethyl alcohol – rose, lilac

The Australian Wine

Research Institute

Grape metabolites influenced by mechanical and yeast effects

• Varietal thiols for Sauv Blanc (some riesling/chard)

• Tannin

• Colour

• Polysaccharides

• Fatty acids (short and medium chain)

Fruity thiols

• Cysteine, glutathione conjugates, released by yeast metabolism

• Sauvignon Blanc, Riesling, Chardonnay, Cabernet Sauvignon

Aroma threshold

4-methyl mercaptopentanone 4-MMP 0.8 ng/L

3-mercaptohexanol 3-MH 60 ng/L

3-mercaptohexyl acetate 3-MHA 4 ng/L

The Australian Wine

Research Institute

The Australian Wine

Research Institute

Factors affecting fruity thiols

• Ripening - Low levels of precursors until commercial harvest

• Processing/transportation – precursors are sensitive to oxidation – a combination of both SO2 and Ascorbic acid

optimum

BUT very high SO2 suppresses conjugate formation

• Yeast choice – turn a Chardonnay into Sauvignon Blanc!!

26

Grape colour correlates with wine colour

Riverland Shiraz trial

0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4

Grape colour (mg/g)

0

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Win

e c

olo

ur

(AU

)

But grape colour does not equal wine colour

Anthocyanins are

not the final stable

colour in wine – they

react with tannin to

produce pigmented

tannins (or “pigmented

polymers”)

0 10 20 30 40 50 60 70 80 90 100 DAY

0

100

200

300

Va

lue

The concentration of

M3G increases during

fermentation until taken

off skins, then it rapidly

declines, while

pigmented tannins

increase

M3G

Pigmented Tannins

[PP] = 0.06 [ M3G ] + 0.04 [ T ] - 2.88

R2 = 0.92

PP: pigmented polymers

M3G: malvidin 3-glucoside

T: tannins

If we know the tannin and anthocyanin concentrations we

can predict final, stable wine colour

Predicting wine pigmented tannin potential

Tannin correlates with commercial quality grading

2005-2007 Hardy Shiraz - but also applied to Fosters and Orlando wines

A B C D E F G H I

Quality grade

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nn

in

(g/L

ep

ica

t)

Mercurio, M.D., Dambergs, R.G., Cozzolino, D., Herderich, M.J, Smith, P. A. (2010) Relationship between red wine grades and phenolics 1. tannin and total phenolics concentrations. J. Agric. Food Chem., 58: 12313–12319

The Australian Wine

Research Institute

Adel Morn Pad Tas Yarra

Region

0

1

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Tann

in (

g/L

)Adel

BarCan

Clare

CoonaLang

MDar

Marg

Mva

lePad

PyrenRland

RuthSwan

Wra

t

Region

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nin

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AdelBar

CanClare

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RuthSwan

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t

Yarra

Region

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nin

(g/L

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Cabernet sauvignon Shiraz Pinot noir

Wine Tannin varies with region

Tannin and pigment in context with

commercial wine styles

The Pinot Shop “...Avancé is a very charming pinot. The fruit has a sweet suppleness. It is quite delicate but there’s nice liveliness and freshness with florals and red berries..”

$29.50

The Pinot Shop “…Reveur (‘dreamer’) Pinot Noir is a pure but weighty wine with distinct charry-cherry characters. That’s from some good oak wrapped around vintage 2008’s ripe Coal Valley fruit. The tannins are round and chewy ……I suspect that the ripe tannins will smooth out into silky, luscious pinot..”

$46

Tannin 1.31 g/L Pigmented tannin 1.14 AU Total Pigment 8.11 AU

Tannin 1.84 g/L Pigmented tannin 1.56 AU Total Pigment 11.42 AU

i.e. Pinot tannin is worth $42,000/Kg

Correlation of tannin and wine colour density: cool season

Cabernet Shiraz

Tan

nin

(e

pic

at. e

q. g

/L)

5

8 9 10 11 12 13 14 15 1

2

3

4

R= 0.47

Tan

nin

(e

pic

at. e

q. g

/L)

9 10 11 12 13 14 15 1

2

3 R= 0.42

Colour density (AU) Colour density (AU)

Correlation of tannin and wine colour density: hot season

Cabernet Shiraz

R = 0.66 R = 0.78

5 10 15 20

Colour density (AU)

1

2

3

Tan

nin

(e

pic

at. e

q. g

/L)

5 10 15

Colour density (AU)

1

2

* Colour and data analysis performed by Dr. R. Dambergs

A model of tannin extraction, desorption and adsorption during fermentation

0.00

200000.00

400000.00

600000.00

800000.00

1000000.00

1200000.00

0 2 4 6 8 10

PA1

PA2

PA3

PA4/5

low MW polys

low MW polys

Medium MW polys grape derived

High MW polys yeast derived

Astringency modulation Hotness suppression? Texture/viscosity? Roles in white vs red?

Polysaccharides in Australian Shiraz across quality grades

Quality grade

The Australian Wine

Research Institute environment

• 1,8-cineol (Eucalyptol)

• Smoke taint

• Regionality – other aromas from plants?

The Australian Wine

Research Institute 1,8 cineole - Eucalyptol

• Terpenoid

• Eucalyptus, mint, camphor

• Can be both grape-derived and from eucalyptus trees near vineyards

• Cineole levels increase during skin contact

The Australian Wine

Research Institute

• Out of 146 commercially available red

wines of various varieties we analysed,

40% of them contained 1,8-cineole above

reported detection threshold.

The Australian Wine

Research Institute mysteries

• Benzyl mercaptan (struck flint)

• Low molecular weight sulphur compounds

• DMS

– Red wine character

– Partly grapes, partly yeast

– Blackcurrant, dark fruit at moderate levels

– Undesirable cooked veg at higher

A tool to characterise and communicate Pinot Grigio and Pinot Gris wine ‘style’

42

…and there is now a Grape and

Wine Tannin Portal

BUT......................

Our industry collaborators

Our funding bodies

Acknowledgments