Paulo Lopes Enologist PhD (Faculté d’Œnologie de Bordeaux) WineMBA (BEM Bordeaux Management School) Gourmet Food & Wine Expo Toronto, November 20 th 2014

Paulo LopesEnologist PhD (Faculté d’Œnologie de Bordeaux)WineMBA (BEM Bordeaux Management School)

Gourmet Food & Wine Expo

Toronto, November 20th 2014

WINE FAULTS WORKSHOP

REDUCTION IN WINE IN RELATION WITH POST BOTTLING

EVOLUTION

MAIN TOPICS OF THIS SENSORIAL EXPERIENCE

• Wine development during post-bottling

• Identify “reductive” development and distinguish it from oxidation by tasting

• Understand the contribution of different winemaking parameters, e.g. closures on wine quality during post-bottling

• How to prevent oxidative and reductive “off-flavors” and its impact on wine quality

UNIÃO EUROPEIAFundo Europeu

de Desenvolvimento Regional

POST-BOTTLING PROFILES OF WINE EVOLUTION

Reduction Oxidation

Equilibrium area = Positive Oxidation or Reduction

Positive Reduction

Negative Oxidacion

Positive Oxidation

Negative Reduction

Pascal Chatonnet (2013)



POST-BOTTLING PROFILES OF WINE EVOLUTION

sewagerotten eggscabbageburnt match

mineralsilextoasty

chocolatevanillapralinejam

berry fruitstropical fruitscitrusfloralspicy

acetaldehydesherryportcooked fruitsbruised apple

Oxygen exposure

Negativereduction

Negative oxidation



TASTING EXPERIENCE

1Control



TASTING EXPERIENCE

1Control

3Hydrogen sulfide

H2S2 mg/L

4Ethanethiol CH3CH2SH#20 µg/L

2 Acetaldehyde

C2H4O100 mg/L

5Methanethiol

CH3SH#20 µg/L



TASTING EXPERIENCE

1Control

3Hydrogen sulfide

H2S2 mg/L


2 Acetaldehyde

C2H4O100 mg/L

5Methanethiol

CH3SH#20 µg/L

REDUCTIONOXIDATION



TASTING EXPERIENCE

1Control

3Hydrogen sulfide

H2S2 mg/L


2 Acetaldehyde

C2H4O100 mg/L

5Methanethiol

CH3SH#20 µg/L

OXIDATION



COMPOUNDS RESPONSIBLE FOR WINE OXIDATION

Acetaldehydebruised apple, sherry, nutty

Olfactory threshold : 40 mg/L

Benzaldehydenutty, sherry


Phenylacetaldehydehoney, rose, “farm-feed”


Methional“Boiled-potato”

Olfactory threshold : 0,5 mg/L

Sotolonnutty, rancid, curry


2-aminocetophenonerancio, “foxy”

Olfactory threshold: 0,7 à 1 mg/L

2



RECOGNIZING OXIDATION

• Color: the vivid purple or cherry-red colors turns into a brick-red or even brown hue; whites darken dramatically, taking on a golden-brown color

• Nose: loss of fresh and fruity aromas, flat. Apple-cider notes of acetaldehyde in white wines and reds will smell like cooked fruits, tired and fruitless, port

• Palate: dry, diluted, bitter character dominates



CAUSES OF WINE OXIDATION

Wine oxidizes when over exposed to oxygen or oxidants throughout winemaking

Exposure of the wine to oxygen is crucial at certain stages (fermentation, racking, barrel aging) of the process, and getting this right is one of the keys to successful winemaking




After bottling it will depend on the sealing effectiveness of closure

0 4 8 12 16 20 24 28 32 360

1

2

3

4

5

6

7

8

9

10Series1

Series5

Series9

Series13

Plastic

Natural cork

Microagglomerate cork

Screw cap

Storage time (months)

O2

(mg/

L) b

ottle

750

mL




After bottling it will depend on the sealing effectiveness of closure

Cork Plastic Screw cap*

O2

O2

*Depend on the liner :Saran-tin – impermeable

Saranex – slightly permeableLOPES, P.; SAUCIER, C.; TEISSEDRE, P.L., GLORIES, Y. Main routes of oxygen ingress through different closures into wine bottles. J. Agric. Food Chem. 2007,55, 5167-5170.

O2



CAUSES OF POST-BOTTLING OXIDATION

Incidence of oxidative characters according to the type of closure

Natural

cork

Plastic

Screw ca

p0.0

0.4

0.8

1.2

1.6

2.0[Sotolon] at 24 months (mg/L)

LOPES, P.; SILVA, C.; TAKATOSHI, T.; LAVIGNE, V.; PONS, A.; SAUCIER, C.; DARRIET, P.; TEISSEDRE, P.L.; DUBOURDIEU, D. Impact of dissolved oxygen at bottling and transmitted through closures on the composition and sensory properties of Sauvignon blanc during bottle storage. J. Agric. Food Chem. 2009, 57, 10261-10270.



CAUSES OF POST-BOTTLING OXIDATION

Incidence of oxidative characters according to the type of closure

Ampoule Cork Plastic

AWRI annual report 2013. page 26



WINE OXIDATION - TEMPERATURE

Heat increases the rate of chemical reactions, including oxidation events Temperature catalyze chemical reactions that wouldn’t occur at lower temperatures

Wines kept at elevated temperatures don’t just age faster, but age worse

Oxidation

Storage temperature 20 to 25ºC

Storage temperature 10 to 12ºC



TASTING EXPERIENCE

1Control

3Hydrogen sulfide

H2S2 mg/L


2 Acetaldehyde

C2H4O100 mg/L

5Methanethiol

CH3SH#20 µg/L

REDUCTION



COMPOUNDS RESPONSIBLE FOR WINE REDUCTION

Volatile Sulfur Compounds (VSC)

Typifying scents

Long chain polyfunctional thiols

Masks wine fruitiness &varietal notes

“off-flavor” reductive characters

short-chain thiols, sulfides, disulfides, thioesters and heterocyclic compounds

Good – positive impact



Bad – negative impact

COMPOUNDS RESPONSIBLE FOR WINE REDUCTION



Volatile sulfur compounds (VSC)

Sewage Rotten eggs

Cabbage

Burnt rubber

Asparagus

Garlic Onion Silex

Struck flintBurnt match

citrus peel

Grapefruit

gooseberry

Broom

Passion fruit

Toasted coffeeAcacia flower

BriocheBaking

GOOD VOLATILE SULFUR COMPOUNDS

Typical box-tree, tropical and grape fruit aromas

3-mercaptohexan-1-ol (3MH)Passion fruit (R), Grapefruit (S)

Olfactory threshold : 50 / 60 ng/L

3-mercaptohexylacetate (3MHA)Passion fruit (R), citrus (S)

Olfactory threshold : 9 / 2,5 ng/L

4-mercapto-4-methylpentan-2-one (4MMP)Broom…cat’pee

Olfactory threshold : 0,8 ng/L



GOOD VOLATILE SULFUR COMPOUNDS

These compounds are also present in Chardonnay and red varieties (Cabernet Sauvignon, Merlot, Pinot Noir); however, they don’t have a such powerful impact on their varietal characters

Typical box-tree, tropical and grape fruit aroma of different varietal wines



BAD VOLATILE SULFUR COMPOUNDS

At subthreshold levels they can contribute to the wine aromatic complexity

345

Compounds responsible for wine reduction



INFLUENCE OF THE BAD VSC ON THE PERCEPTION OF THE WINE’S FLAVOR?

It also a matter of concentration!

High level of VSC

Off-flavors !

Excessive but not high level of VSC

Muting effect (mask)

Loss of typical aroma/flavor due to

the competition by the excess of bad VSC

Low level of VSC

Optimum level for the expression of the

qualitative potential of the wine !

No VSC

Wine is oxidised..!



RECOGNIZING REDUCTION

• Color: no change;

• Nose: very intense fresh aromas dominated by peas or vegetal, burnt match, rubber onion, garlic, cooked cabbage, rotten eggs or putrefaction;

• Palate: extremely astringent, bitter, presenting metallic flavours



Sulfur amino acids or peptides

ORIGIN OF VSC DURING WINEMAKING



Reduction

Sulfates

Inorganic sulfur

Sulfur dioxide

Pesticides containing S

Yeast strain deficiency of vitamins and nutrients

Low temperature

High level of solids & turbidity

Very low redox potential

High level of ions (Fe, Cu)

Photochemical (white glass)

ORIGIN OF VSC DURING WINEMAKING

Pesticides

Grape composition

Must composition and yeast strain activity during

fermentationAgeing



AFTER BOTTLING THE FORMATION OF VSC DEPEND ON THE SEALING PROPERTIES =

PERMEABILITY OF CLOSURES

PHOTOCHEMICAL ORIGIN OF VOLATILE SULFUR



Wines stored in flint bottles - ‘sunlight flavor’

Exposure to light, especially in the higher energy UV that are not totally absorbed by bottle glass, puts riboflavins(vitamin B2) in an excited, high-energy state which lead to the oxidative photodegradation of methionine

Cooked potato aroma

Cabbage, onion

Rotten cabbage,

THE IMPORTANCE OF CLOSURE O2 TRANSMISSION

0 4 8 12 16 20 24 28 32 360

1

2

3

4

5

6

7

8

9

10Series1

Series5

Series9

Series13

Plastic

Natural cork

Microagglomerate cork

Screw cap

Storage time (months)

O2

(mg/

L) b

ottle

750

mL



IMPACT OF CLOSURE ON THE GOOD VSC

Natural cork

Plastic Screw cap

0

200

400

600

800

1000

3 M

H (n

g/L)

at 2

4 m

onth

s

3-mercaptohexan-1-ol (3MH)

Natural cork

Plastic Screw cap

0

5

10

15

20

25

30

4 M

MP(

ng/L

) at 2

4 m

onth

s

4-mercapto-4-methylpentan-2-one (4MMP)

Compounds responsible for the fruity characters are very sensitive to O2!!!



IMPACT OF CLOSURE ON THE BAD VSC

Impact of closures on post-bottling reduction – formation of compound number 3

Bottling Natural cork

Plastic Screw cap

0

5

10

15

20

25

30H2S at 24 months (mg/L)

LOPES, P.; SILVA, C.; TAKATOSHI, T.; LAVIGNE, V.; PONS, A.; SAUCIER, C.; DARRIET, P.; TEISSEDRE, P.L.; DUBOURDIEU, D. Impact of dissolved oxygen at bottling and transmitted through closures on the composition and sensory properties of Sauvignon blanc during bottle storage. J. Agric. Food Chem. 2009, 57, 10261-10270.



POST-BOTTLING REDUCTION

Impact of closures on post-bottling reduction

SKOUROUMOUNIS, G.K.; KWIATKOWSKI, M.J.; FRANCIS, I.L.; OAKEY, H.; CAPONE, D.; DUNCAN, B.; SEFTON, M.A.; WATERS, E.J. The impact of closure type and storage conditions on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years’storage. Aust. J. Grape and Wine Res. 2005, 11, 369-384

0

1

2

3

4

5Riesling

Oxidised Reductive

0

1

2

3

4

5Chardonnay

Oxidised Reductive



POST-BOTTLING REDUCTION

Impact of closures on post-bottling reduction – Shiraz at 36 months

-1 -0.5 0 0.5 1 1.5-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

Dark fruit

Red fruit

Cooked fruit

Vanilla

Sweet spices

Chocolate

Viscosity

Sewage/Drain

Cooked Vegetal

Eucalypt/Pine

Pungent

Port/Bruised apple

Free SO2

Total SO2

Dimethyl sulfide

Carbon disulfide

F1 (47,18 %)

F2 (2

3,24

%)

-4 -2 0 2 4 6-4

-2

0

2

4

Natural cork

Diam D5

Microagglomerate

1+1

Nomacorc

Screw capSaranex

Screw cap saran-tin

reducedBalanced

Premature oxidation



CAUSES OF POST-BOTTLING REDUCTION

SulfitesPesticides

Sulfate

Sulfur contaniningaminoacids

SO2

Inorganicsulfur

H2S

Rotten egg, sewage like aroma

CH3CH2OHEthanol

CH3CH2SHEthanethiol

Onion, rubbery, burnt match aroma

OH

OH

O

O

O

O

catechol

quinone semiquinone

?? Metal Catalyzed



CHEMICAL PROPERTIES OF VSC

Sensitive to oxidation

Strong affinity towards quinones which result of phenolic oxidation

React with copper



HOW TO PREVENT THE POST-BOTTLING REDUCTION

Reduce the level of sulfur forms in wines, e.g. sulfur dioxide

Oxidation of (VSC) by increase the wine exposure to oxygen

Increase the oxygen in the headspace at bottling…limited effectiveness

Increase the oxygen transmission rate of the stopper (OTR)…risks of oxidation

Elimination of VSC and precursors of VSC by Copper fining



2 H2S + O2 2 H2O + 2 S

4 C2H5SH + O2 2 C2H5SSC2H5 + 2 H2O

Rotten eggs odorless

Rubber, struck flint

Sensory threshold = 1.1 mg/LGarlic, burnt rubber

Sensory threshold = 4.3 mg/L

COPPER TREATMENT, PREVENT THE POST-BOTTLING REDUCTION

1Control

3Hydrogen sulfide

H2S2 mg/L


2 Acetaldehyde

C2H4O100 mg/L

5Methanethiol

CH3SH#20 µg/L

+ Cu SO4+ Cu SO4

COPPER TREATMENT, PREVENT THE POST-BOTTLING REDUCTION

H2S + CuSO4 → CuS + H2SO4

Adding Cu2+ under the form of cupric sulfate or citrate (legal limit 1g/hL) allows the

bad VSC such as the hydrogen sulfide to precipitate copper sulfide, according to

the

2 3-MH-SH + Cu++ + e- → MH-S-S-MH + Cu+ + 2H+

However, it also removes thiols compounds responsible for fruity characters

Passion fruit No aroma

Side effect



It also demonstrated that under low redox-potential (screw cap sealed wines),

copper increase the levels of H2S and other reductive compounds over time

“TAKE HOME MESSAGES”

Wine evolution during post-bottling is highly dependent on the oxygen barrier properties of closures (closure OTR)…is not possible to lock a wine in time

Don’t manage the risk of post-bottling “reduction” by increasing the oxidative status of the wine, or treating it with copper ! Prevent any bad evolution by appropriate viticulture, winemaking practice and choice of closure !

Too low OTR: reductive characters emerge

Appropriate OTR: deals with reductive characters, while preserving fruity notes

Too much OTR: risk of oxidation, loss of varietal characters



THANK YOU FOR YOUR ATTENTION

QUESTIONS, CRITICS, COMMENTS

[email protected]

Documents

Paulo Lopes Enologist PhD (Faculté d’Œnologie de Bordeaux) WineMBA (BEM Bordeaux Management School) Gourmet Food & Wine Expo Toronto, November 20 th 2014