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Premature ageing of wine aromas

Premature ageing of wine aromas. Denis Dubourdieu and Valérie Lavigne,. That is the question. Premox or not Premox. When Premox phenomenon shake the web. Estimation. Sources : google, private blog and web site (R.Parker, J.Robinson). Manifestations of defective aromatic ageing

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Premature ageing of wine aromas

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  1. Premature ageing of wine aromas Denis Dubourdieu and Valérie Lavigne,

  2. That is the question Premox or not Premox WhenPremoxphenomenonshake the web Estimation Sources : google, private blog and web site (R.Parker, J.Robinson)

  3. 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

  4. Olfactometric detection (C-P-G)

  5. Comparison of aromagrams obtained from honey extracts and ones from white wine containing honey

  6. Aromagrams of honey extracts and of white wine containing honey Sensory descriptors Retention time Organic extract Organic extract (min.) from from honey wine 10.34 strawberry 13.25 overripe pineapple 14.5 hydrocarbons 15.53 herbaceous herbaceous, forest floor 18.18 burnt meat 19.15 tobacco, cigar 19.53 cep 22.22 mushroom 22.36 vinegar grapefruit, lemon 22.55 26.37 orange 32.43 bitter almond bitter almond 32.53 candied fruit 38.17 peaches in syrup 44.02 apricot 47.44 rose rose ZO1 ZO2 honey honey 50.17 53.5 resin resin 54.22 mothballs mothballs 60.2 beeswax beeswax 62.3 vanilla vanilla

  7. Main molecules involved in the "defective" ageing of white wines.

  8. Methional Boiled potatoes 0.5 µg/L Methionine (Ferreira et al., 2002) S O Phenylacetaldehyde Wilted roses, honey 25 µg/L Phenylalanine (Ferreira et al., 2002) O O Oxidation o-aminoacetophenone Moth balls, wax polish 0.7 µg/L Indolacetic acid C H 3 N H 2 Aromatic markers for defective ageing of dry white wines Carbonyl compounds O2

  9. These molecules cannot alone explain aromatic defects during ageing because certain prematurely aged wines do not contain them.

  10. H C O H 3 * O H C 3 O Contribution of sotolon to the oxidised aroma of wine 3-hydroxy-4.5-dimethyl-2(5H)-furanone (Curry, walnuts) • 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 mixture7 µg/L

  11. Organoleptic characteristics of sotolon

  12. H O C H H C O H 3 3 C H H C 3 3 O O O O H H Sotolon: a chiral molecule The existence of one or several asymmetrical carbons can be responsible for attributing different olfactory characteristics to each enantiomer. R S

  13. Perception thresholds (µg/L) Descriptors Model solution R 89 W alnuts , rancio S 0.8 (Curry, walnuts) Racemate 2 (Curry, walnuts) Perception threshold of each enantiomer of sotolon • 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.

  14. Distribution of various enantiomers of sotolon in dry white wines in bottle 50/50 30/70 70/30 • Racemic mixutre 100 80 • Excess (S)-sotolon 60 % • Excess (S)-sotolon 40 20 0 PL 87 PL 75 PL 81 PL 73 Bx 99 Bx 99 EDM 00 EDM 01 EDM 00 Graves 80 Graves 81 The olfactory detection threshold determined from a commercial sotolon racemic mixture is insufficient to appreciate the olfactory impact of this compound on wine.

  15. How sotolon is formed in dry white wines. H O O aldocondensation C O O H H O O O Ethanal α-ketobutyric acid Sotolon

  16. What are the constituents of white wines likely to prevent the formation of these compounds?

  17. 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

  18. Glutathion (Glu CysGly) COO - H+3N CH CH2COO - CH2CONHCH2 CONHCH CH2 SH Glycine Acide glutamique Cystéine

  19. Glutathion in must and wine

  20. 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.

  21. 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 62 244 76 202 224 56 187 42 12 28 17 28 25 6 22 4 Available nitrogen (mg/L) Glutathion (mg/L)

  22. 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.

  23. Reaction of adding a thiol (R-SH)to the catechin quinone O OH O Oxidation OH H O O H O O O O O H O H Oxidised catechin (quinone) Reduced catechin R-SH Thiol (aroma, glutathion,etc.) O H O H H O O S O H R O H adduct

  24. 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 12 28 17 28 25 6 22 4 Glutathion (mg/L)

  25. Changes in glutathion content during alcoholic fermentation

  26. 12 10 8 6 4 2 0 Changes in glutathion content in must during alcoholic fermentation concentration of glutathion (mg/L) must T1 T3 T6 T9 sulphiting T20 T30

  27. Relation between levels of glutathion in must and in young wine 9 5 4 17 2 11 7 6 22 3 Glutathion in must (mg/L) Glutathion in the corresponding wine (mg/L)

  28. 30 25 20 15 10 5 0 Relationship between the initial glutathion content of a model medium and the level at the end of alcoholic fermentation. Concentration of glutathion (mg/L) Level of glutathion in the medium before AF Level of glutathion in the medium after AF

  29. Relationship between the level of available nitrogen and the level of glutathion at the end of alcoholic fermentation. Concentration of glutathion (mg/L) 25 20 15 T0 End of AF 10 5 0 48 96 190 Level of available nitrogen in the model medium (mg/L)

  30. Signs of premature ageing of aromas in white wines

  31. During ageing

  32. 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

  33. 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

  34. 1600 1400 1200 1000 800 End of AF 600 November 400 April 200 0 Used Used Barrel barrel Changes in the level of 3-MH in a Sauvignon Blanc wine aged different ways in barrel Concentration of 3-M (ng/L) Used barrel New barrel racked racked

  35. 9 8 7 6 5 4 3 2 1 0 Amount of sotolon in the wines at the end of barrel ageing Concentration of sotolon (µg/L) Detection threshold (white wine) Barrel Used barrel Barrel New barrel used on the lees new on the lees without lees without lees

  36. 18 16 14 12 10 8 6 4 2 0 May End of AF December January February Effect of barrel ageing techniques on changes in the glutathion level of wines concentration of glutathion (mg/L) new barrel on the lees new barrel without lees used barrel on the lees used barrel without the lees Samples

  37. Glutathion Sotolon 3-MH 1.3 9.7 1400 420 5.8 0.5 Used barrel on the lees New barrel without the lees Glutathion, a natural component of grapes makes it possible to prevent the defective ageing of white wines. Glutathion, sotolon and 3-mercapto-hexanol at the end of barrel ageing (mg/L) (ng/L) (µg/L) The same ageing conditions most conducive to preserving the aromatic characteristics of dry white wines also limit a decrease in the level of glutathion.

  38. Interpretation of the protective role of lees • with regard to defective aromatic ageing • Release of reductive compounds • Oxygen fixation by the lees

  39. 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)

  40. Manifestation of premature ageing once the wine is bottled

  41. Identification of the random nature of premature ageing in two dry white wines (tasting in 2005 of 12 bottles of each wine) 70 60 Graves 2001 50 40 % 30 20 10 0 Little or no signs of age Showing average signs of age Looking very aged 1997 Pessac Léognan 70 60 50 40 % 30 20 10 0 Little or no signs of age Showing average signs of age Looking very aged

  42. 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 2 R 0.7084 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

  43. Effect of dissolved oxygen content on colour 2 = 0.8315 R 0.4 0.3 DO420 nm 0.2 0.1 0 0 10 20 30 40 50 60 70 80 90 Level of dissolved oxygen (µg/l)

  44. Correlation between free SO2and dissolved oxygen 25 20 15 Free SO2 (mg/l) 2 R = 0.7909 10 5 0 0 20 40 60 80 100 120 140 Level of dissolved O2 (µg/l)

  45. 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 80 100 120 140 Dissolved oxygen in bottle (µg/l)

  46. Dissolved oxygen measured in white wine six months after bottling Effect of closure… 120 100 80 Level of oxygen (µg/l) 60 40 20 0 1 4 5 2 3 Types of closure used

  47. Changes in the level of free SO2 in bottle Effect of closure… 30 25 Free SO2 (mg/l) 20 15 1 2 3 4 5 Types of closure used

  48. 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

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