WINE FAULTS WORKSHOP
REDUCTION IN WINE IN RELATION WITH POST BOTTLING EVOLUTION
Paulo Lopes
Enologist PhD (Faculté d’Œnologie de Bordeaux)
WineMBA (BEM Bordeaux Management School)
Gourmet Food & Wine Expo
Toronto, November 20th 2014
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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
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POST-BOTTLING PROFILES OF WINE EVOLUTION
Positive
Oxidation
Positive
Reduction
Reduction
Oxidation
Negative
Reduction
Negative
Oxidacion
Equilibrium area = Positive Oxidation or Reduction
Pascal Chatonnet (2013)
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POST-BOTTLING PROFILES OF WINE EVOLUTION
sewage
rotten eggs
cabbage
burnt match
mineral
silex
toasty
berry fruits
tropical fruits
citrus
floral
spicy
Negative
reduction
chocolate
vanilla
praline
jam
acetaldehyde
sherry
port
cooked fruits
bruised apple
Negative
oxidation
Oxygen exposure
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TASTING EXPERIENCE
1
Control
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TASTING EXPERIENCE
1
2
3
4
5
Control
Acetaldehyde
C2H4O
100 mg/L
Hydrogen sulfide
H2S
2 mg/L
Ethanethiol
CH3CH2SH
#20 µg/L
Methanethiol
CH3SH
#20 µg/L
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TASTING EXPERIENCE
OXIDATION
REDUCTION
1
2
3
4
5
Control
Acetaldehyde
C2H4O
100 mg/L
Hydrogen sulfide
H2S
2 mg/L
Ethanethiol
CH3CH2SH
#20 µg/L
Methanethiol
CH3SH
#20 µg/L
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TASTING EXPERIENCE
OXIDATION
1
2
3
4
5
Control
Acetaldehyde
C2H4O
100 mg/L
Hydrogen sulfide
H2S
2 mg/L
Ethanethiol
CH3CH2SH
#20 µg/L
Methanethiol
CH3SH
#20 µg/L
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COMPOUNDS RESPONSIBLE FOR WINE OXIDATION
2
Acetaldehyde
Phenylacetaldehyde
Sotolon
bruised apple, sherry, nutty
honey, rose, “farm-feed”
nutty, rancid, curry
Olfactory threshold : 40 mg/L
Olfactory threshold : 25 mg/L
Olfactory threshold : 2 mg/L
Benzaldehyde
Methional
2-aminocetophenone
nutty, sherry
“Boiled-potato”
rancio, “foxy”
Olfactory threshold : 3 mg/L
Olfactory threshold : 0,5 mg/L
Olfactory threshold: 0,7 à 1 mg/L
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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
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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
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CAUSES OF WINE OXIDATION
After bottling it will depend on the sealing effectiveness of closure
O2 (mg/L) bottle 750 mL
10
9
Series4
8
Series5
7
Series6
6
Series8
5
Plastic
4
Natural cork
3
Microagglomerate cork
2
Screw cap
1
0
0
4
8
12
16
20
24
28
32
36
Storage time (months)
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CAUSES OF WINE OXIDATION
After bottling it will depend on the sealing effectiveness of closure
O2
O2
O2
Cork
Plastic
Screw cap*
*Depend on the liner :
Saran-tin – impermeable
LOPES, 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.
Saranex – slightly permeable
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CAUSES OF POST-BOTTLING OXIDATION
Incidence of oxidative characters according to the type of closure
[Sotolon] at 24
months (mg/L)
2.0
1.6
1.2
0.8
0.4
0.0
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.
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CAUSES OF POST-BOTTLING OXIDATION
Incidence of oxidative characters according to the type of closure
Ampoule
Cork
AWRI annual report 2013. page 26
Plastic
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WINE OXIDATION - TEMPERATURE
Storage temperature
20 to 25ºC
Storage temperature
10 to 12ºC
Oxidation
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
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TASTING EXPERIENCE
REDUCTION
1
2
3
4
5
Control
Acetaldehyde
C2H4O
100 mg/L
Hydrogen sulfide
H2S
2 mg/L
Ethanethiol
CH3CH2SH
#20 µg/L
Methanethiol
CH3SH
#20 µg/L
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COMPOUNDS RESPONSIBLE FOR WINE REDUCTION
Volatile Sulfur Compounds (VSC)
Good – positive impact
Bad – negative impact
Typifying scents
Masks wine fruitiness &varietal notes
Long chain polyfunctional thiols
“off-flavor” reductive characters
short-chain thiols, sulfides, disulfides,
thioesters and heterocyclic compounds
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COMPOUNDS RESPONSIBLE FOR WINE REDUCTION
Sewage
Toasted coffee
Brioche
Baking Acacia flower
Rotten eggs
Broom
Cabbage
citrus peel
Volatile sulfur compounds (VSC)
Burnt rubber
Passion fruit
Asparagus
Garlic
gooseberry
Onion
Burnt match
Struck flint
Grapefruit
Silex
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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
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GOOD VOLATILE SULFUR COMPOUNDS
Typical box-tree, tropical and grape fruit aroma of different varietal wines
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
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BAD VOLATILE SULFUR COMPOUNDS
Compounds responsible for wine reduction
3
4
5
At subthreshold levels they can contribute to the wine aromatic complexity
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INFLUENCE OF THE BAD VSC ON THE PERCEPTION
OF THE WINE’S FLAVOR?
It also a matter of concentration!
High level of VSC
Excessive but not
high level of VSC
Low level of VSC
No VSC
Off-flavors !
Muting effect
(mask)
Loss of typical
aroma/flavor due to
the competition by the
excess of bad VSC
Optimum level for the
expression of the
qualitative potential of the
wine !
Wine is oxidised..!
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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
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ORIGIN OF VSC DURING WINEMAKING
Sulfates
Yeast strain
Sulfur amino acids
or peptides
Low
temperature
Reduction
Sulfur dioxide
Inorganic sulfur
Pesticides
containing S
deficiency of vitamins
and nutrients
Photochemical
(white glass)
High level of solids
& turbidity
Very low redox
potential
High level of ions
(Fe, Cu)
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ORIGIN OF VSC DURING WINEMAKING
Grape composition
Must composition and yeast
strain activity during
fermentation
Ageing
Pesticides
AFTER BOTTLING THE FORMATION OF VSC DEPEND ON
THE SEALING PROPERTIES = PERMEABILITY OF CLOSURES
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PHOTOCHEMICAL ORIGIN OF VOLATILE SULFUR
Wines stored in flint bottles - ‘sunlight flavor’
Cooked potato aroma
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
Rotten cabbage,
Cabbage, onion
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THE IMPORTANCE OF CLOSURE O2 TRANSMISSION
O2 (mg/L) bottle 750 mL
10
9
Series4
8
Series5
7
Series6
6
Series8
5
Plastic
4
Natural cork
3
Microagglomerate cork
2
Screw cap
1
0
0
4
8
12
16
20
24
28
32
36
Storage time (months)
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IMPACT OF CLOSURE ON THE GOOD VSC
1000
30
800
4 MMP(ng/L) at 24 months
3 MH (ng/L)at 24 months
3-mercaptohexan-1-ol
(3MH)
600
400
200
0
25
4-mercapto-4-methylpentan-2-one
(4MMP)
20
15
10
5
0
Natural cork
Plastic
Screw cap
Natural cork
Plastic
Screw cap
Compounds responsible for the fruity characters are very sensitive to O2!!!
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IMPACT OF CLOSURE ON THE BAD VSC
Impact of closures on post-bottling reduction – formation of compound number 3
H2S
at 24 months
(mg/L)
30
25
20
15
10
5
0
Bottling
Natural
cork
Plastic Screw cap
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.
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POST-BOTTLING REDUCTION
Impact of closures on post-bottling reduction
Riesling
5
Chardonnay
5
Oxidised
Oxidised
Reductive
4
4
3
3
2
2
1
1
0
0
Reductive
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
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POST-BOTTLING REDUCTION
Impact of closures on post-bottling reduction – Shiraz at 36 months
41
Balanced
reduced
Eucalypt/Pine
0.75
Carbon disulfide
Viscosity
2
0.5
Vanilla
F2 (23,24 %)
Screw cap
Saranex
Diam D5
0.25
1+1
Free SO2
Sweet spices
Total SO2
Pungent cork
Natural
00
Microagglomerate
Dimethyl sulfide
Dark fruit
Cooked fruit
Chocolate
-0.25
Screw cap sarantin
-2
-0.5
Sewage/Drain
Red fruit
Port/Bruised apple
-0.75
Cooked Vegetal
Nomacorc
-4
-1
Premature oxidation
-4
-1
-0.8
-0.6-2
-0.4
-0.2
0
0
F1 (47,18 %)
0.2
2
0.4
0.6
4 0.8
1
6
1.2
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CAUSES OF POST-BOTTLING REDUCTION
Sulfur
contanining
aminoacids
Sulfate
SO2
Pesticides
Inorganic
sulfur
Sulfites
OH
OH
catechol
??
O
Metal Catalyzed
O
O
O
Ethanol
quinone
CH3CH2OH
semiquinone
H2S
Ethanethiol
CH3CH2SH
Onion, rubbery, burnt match aroma
Rotten egg, sewage like aroma
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CHEMICAL PROPERTIES OF VSC
 Sensitive to oxidation
 Strong affinity towards quinones which result of phenolic oxidation
 React with copper
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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
2 H2S + O2
Rotten eggs
4 C2H5SH + O2
2 H2O + 2 S
odorless
2 C2H5SSC2H5 + 2 H2O
Rubber, struck flint
Garlic, burnt rubber
Sensory threshold = 1.1 mg/L
Sensory threshold = 4.3 mg/L
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
COPPER TREATMENT, PREVENT THE POST-BOTTLING
REDUCTION
+ Cu SO4
+ Cu SO4
1
2
3
4
5
Control
Acetaldehyde
C2H4O
100 mg/L
Hydrogen sulfide
H2S
2 mg/L
Ethanethiol
CH3CH2SH
#20 µg/L
Methanethiol
CH3SH
#20 µg/L
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COPPER TREATMENT, PREVENT THE POST-BOTTLING
REDUCTION
 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
H2S + CuSO4 → CuS + H2SO4
the
Side effect
However, it also removes thiols compounds responsible for fruity characters
2 3-MH-SH + Cu++ + e- → MH-S-S-MH + Cu+ + 2H+
Passion fruit
No aroma
 It also demonstrated that under low redox-potential (screw cap sealed wines),
copper increase the levels of H2S and other reductive compounds over time
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“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
pdlopes.ai@amorim.com