Premature ageing of wine aromas
Denis Dubourdieu and Valérie Lavigne,
Premox
or not
Premox
When Premox phenomenon
shake the web
That is
the
question
4000
3500
# CITATIONS
3000
Estimation
2500
2000
1500
1000
500
0
2005
2006
2007
2008
2009
2010
YEARS
Sources : google, private blog and web site (R.Parker, J.Robinson)
Manifestations of defective aromatic ageing
in dry white wines
• loss of fruity aromas
• appearance of heavier aromatic nuances
reminiscent of wax polish or wax
• colour with shades of yellow associated
with bitterness on the aftertaste
Olfactometric detection
(C-P-G)
Comparison of aromagrams obtained from
honey extracts and ones from white wine
containing honey
Aromagrams of honey extracts and of white wine
containing honey
Sensory
descriptors
Retention time
(min.)
ZO1
ZO2

10.34
13.25
14.5
15.53
18.18
19.15
19.53
22.22
22.36
22.55
26.37
32.43
32.53
38.17
44.02
47.44
50.17
53.5
54.22
60.2
62.3
Organic extract
from honey
Organic extract
from wine
strawberry
overripe pineapple
hydrocarbons
herbaceous
herbaceous, forest floor
burnt meat
tobacco, cigar
cep
mushroom
vinegar
grapefruit, lemon
orange
bitter almond
candied fruit
bitter almond
peaches in syrup
apricot
rose
rose
honey
resin
mothballs
beeswax
honey
resin
mothballs
beeswax
vanilla
vanilla
Main molecules involved in the "defective" ageing
of white wines.
Aromatic markers for defective ageing of dry
white wines
Methional
S
O
Boiled potatoes
0.5 µg/L
Methionine
(Ferreira et al., 2002)
Carbonyl compounds
O2
O
Phenylacetaldehyde
Phenylalanine
Wilted roses, honey
25 µg/L
(Ferreira et al., 2002)
O
CH3
NH2
o-aminoacetophenone
Moth balls, wax polish
0.7 µg/L
Oxidation
Indolacetic acid
These molecules cannot alone explain
aromatic defects during ageing because certain prematurely
aged wines do not contain them.
Contribution of sotolon to the oxidised aroma of wine
H C
3
OH
3-hydroxy-4.5-dimethyl-2(5H)-furanone
H C
3
(Curry, walnuts)
*
O
O

vins jaunes from the Jura and Sherry (Guichard et al., 1993)

fig and rancio aromas of vins doux naturels (Cutzach, 1999)

walnut aromas of old Port (Ferreira, 2003)

aromas of defective ageing in dry white wines (Lavigne, 2002)
Perception threshold of the racemic mixture 7 µg/L
Organoleptic characteristics of sotolon
Sotolon: a chiral molecule
HO
CH3
CH3
O
O
R
H
H3 C
OH
H3C
H
O
O
S
The existence of one or several asymmetrical carbons can be responsible for
attributing different olfactory characteristics to each enantiomer.
Perception threshold of each enantiomer of sotolon
Perception thresholds (µg/L)
Descriptors
Model solution
R
89
Walnuts, rancio
S
0.8
(Curry, walnuts)
Racemate
2
(Curry, walnuts)
 The S form that gives sotolon its smell and taste characteristics. .
 The (S)-sotolon is solely responsible for premature ageing of the aromas
in dry white wines.
Distribution of various enantiomers of sotolon in dry
white wines in bottle
%
50/50
30/70
70/30
100
 Racemic mixutre
80
 Excess (S)-sotolon
60
40
 Excess (S)-sotolon
20
0
The olfactory detection threshold determined from a commercial sotolon
racemic mixture is insufficient to appreciate the olfactory impact of this
compound on wine.
How sotolon is formed in dry white wines.
HO
O
aldocondensation
C O OH
H
O
α-ketobutyric acid
Ethanal
O
O
Sotolon
What are the constituents of white wines
likely to prevent the formation of these
compounds?
• in red wines: phenolic compounds,
especially anthocyanins, protect young wine
from oxidative phenomena that can detract from its aroma.
• as for white wines, not much is known
about the compounds likely to play a role.
 we have showed that certain sulphur peptides,
in particular glutathion, can play a role
Glutathion
(Glu
Cys
Gly)
COO H+3N
Acide glutamique
Glycine
CH
COO -
CH2
CH2
CO NH CH2
CO NH CH
Cystéine
CH2
SH
Glutathion
in must and wine
Glutathion, a natural component of grapes
 It has been shown to be present in large quantity
in grapes: Cheynier et al, 1989; Liyanage et al., 1993
 The accumulation mechanisms are not well-known.
The nitrogenous intake of vines plays en essential role.
The relation between the levels of available nitrogen and
glutathion in white wine must
Must 1 Must 2 Must 3 Must 4 Must 5 Must 6 Must 7 Must 8
Available nitrogen
(mg/L)
62
244
Glutathion
(mg/L)
12
28
76
17
202
28
224
25
56
6
22
187
4
42
Reactivity of glutathion
 with oxygen: formation of disulphur
 with quinones in the must: formation of GRP
Most of the glutathion in grapes
disappears when the juice is extracted.
Reaction of adding a thiol (R-SH)
to the catechin quinone
O
OH
O
OH
H O
Oxidation
H O
O
O
O
O
O H
O H
Oxidised catechin (quinone)
Reduced catechin
R-SH
O H
O H
H O
O
OH
O H
adduct
S
R
Thiol
(aroma, glutathion,etc.)
Examples of glutathion content in various
Sauvignon Blanc and Sémillon musts
Must 1 Must 2 Must 3 Must 4 Must 5 Must 6 Must 7 Must 8
Glutathion
(mg/L)
12
28
17
28
25
6
22
4
Changes in glutathion content during
alcoholic fermentation
Changes in glutathion content in must during
alcoholic fermentation
concentration of glutathion (mg/L)
12
10
8
6
4
2
0
must
T1
T3
T6
T9 sulphiting T20
T30
Relation between levels of glutathion in must
and in young wine
Glutathion in must
(mg/L)
9
5
4
17
2
Glutathion in the corresponding wine
(mg/L)
11
7
6
22
3
Relationship between the initial glutathion
content of a model medium and the level at
the end of alcoholic fermentation.
30
25
20
15
10
5
0
Level of glutathion in the medium before AF
Level of glutathion in the medium after AF
Relationship between the level of available
nitrogen and the level of glutathion at the end
of alcoholic fermentation.
25
20
15
T0
End of AF
10
5
0
48
96
190
Level of available nitrogen in the model medium
(mg/L)
Signs of premature ageing
of aromas in white wines
During ageing
Traditional ageing on the lees
 Protection of the young wine's fruity aromas
 Maintaining wine in a state of oxidation-reduction
to encourage the appearance of a bouquet showing signs
of reduction: truffle, burnt and mineral nuances .
 Avoids or delays manifestations of aromatic ageing
Influence of ageing techniques on the defective
ageing of wine
 Ageing with or without the lees
 New or used barrels
Evolution - of the fruity aroma
- of defective ageing markers
- of glutathion
Changes in the level of 3-MH in a Sauvignon Blanc
wine aged different ways in barrel
Concentration of 3-M (ng/L)
1600
1400
1200
1000
800
600
400
200
0
End of AF
November
April
Used
Barrel
Used barrel
racked
Used
barrel
New barrel
racked
Amount of sotolon in the wines at the end of barrel
ageing
Concentration of sotolon (µg/L)
9
8
7
6
5
4
3
2
1
0
Detection threshold
(white wine)
Barrel
used
on the lees
Used barrel
without lees
Barrel
new
on the lees
New barrel
without lees
Effect of barrel ageing techniques on changes in the
glutathion level of wines
concentration of glutathion (mg/L)
18
16
14
12
10
8
new barrel on the lees
new barrel without lees
6
used barrel on the lees
4
used barrel without the lees
2
0
End of AF December
January
February
May
Samples
Glutathion, sotolon and 3-mercapto-hexanol
Glutathion, at
a the
natural
component of grapes
end of barrel ageing
makes it possible to prevent the defective ageing of white wines.
Glutathion
Sotolon
3-MH
(mg/L)
(µg/L)
(ng/L)
Used barrel on the lees
5.8
1.3
1400
New barrel without the lees
0.5
9.7
420
The same ageing conditions most conducive to preserving
the aromatic characteristics of dry white wines also
limit a decrease in the level of glutathion.
Interpretation of the protective role of lees
with regard to defective aromatic ageing
-Release of reductive compounds
- Oxygen fixation by the lees
Oxygen consumption (µg/L/h) of a white wine
aged for 6 months entirely its lees
Wine aged on its lees
611
Filtered wine
0.01
Lees alone
542
Heat-treated lees
19
(Fornairon et al., 1999)
Manifestation of premature ageing once
the wine is bottled
Identification of the random nature of premature ageing
in two dry white wines
(tasting in 2005 of 12 bottles of each wine)
%
%
70
60
50
40
30
20
10
0
70
60
50
40
30
20
10
0
Graves 2001
Little or no signs of age
Showing average signs ofLooking
age
very aged
1997 Pessac Léognan
Little or no signs of age
Showing average signs ofLooking
age
very aged
Correlation between the oxygen dissolved in bottled
wines and prematurely-aged aromas
Analyses of 20 samples of a Graves white wine (1997 vintage) after 7 years in bottle.
Average
6.00
R20.7084
5.00
4.00
3.00
2.00
1.00
0.00
0
20
40
60
80
100
120
140
Dissolved oxygen (µg/l)
Importance of oxidative-type reactions throughout bottle ageing
Effect of dissolved oxygen content
on colour
R
2
= 0.8315
0.4
DO420 nm
0.3
0.2
0.1
0
0
10
20
30
40
50
60
70
80
Level of dissolved oxygen (µg/l)
90
Correlation between free SO2
and dissolved oxygen
25
Free SO2 (mg/l)
20
15
2
R = 0.7909
10
5
0
0
20
40
60
80
100
Level of dissolved O2 (µg/l)
120
140
Choice of closure…
Concentration of sotolon (µg/L)
2
R = 0.7191
3.5
3
2.5
2
1.5
1
0.5
0
0
20
40
60
80
100
Dissolved oxygen in bottle (µg/l)
120
140
Dissolved oxygen measured in white wine six months
after bottling Effect of closure…
Level of oxygen (µg/l)
120
100
80
60
40
20
0
1
2
3
Types of closure used
4
5
Changes in the level of free SO2 in bottle
Effect of closure…
Free SO2 (mg/l)
30
25
20
15
1
2
3
Types of closure used
4
5
To prevent the defective ageing of white
wines, IT IS NECESSARY TO
•
•
•
•
•
•
•
have vines with sufficient vigour
limit the extraction of phenolic compounds during pressing
protect both the must and the wine from oxidation
make sure that alcoholic fermentation is completely finished
reduce the lag period for malolactic fermentation
age the wines in reductive conditions
limit the dissolution of oxygen when preparing the wine for
bottling
• choose a closure that is suited to the wine