Synthetic closures: practical solutions

1. Synthetic closures: practical solutions Maurizio Ugliano November 2012

2. Wine bottle aging Sensory quality Time in bottle Wine improves with a period of aging in bottle • Clearly accepted for very high end wines • Still true for most red wines but consumption is very rapid nowadays • Observed often for white wines too, but gerenally less prone to long aging

3. Wine styles and market trends Less oxygen More oxygen

4. What is actually happening? O2 Roasted, smoky Complex black fruits, dry fruit, chocolate, tobacco, Simple fruity aromas Ageing time Bottling Aging with low O2 Aging with high O2 Wine style 2 Wine faults

5. Reduction and wine fruitiness: importance of sulfur compounds Reduction • ‘Good’ sulfur compounds • 3-mercapto • hexanol • 3-mercaptohexyl acetate Fruity aromas Dry fruit, dry flowers, honey Sauvignon blanc, Verdejo, Manseng, Verdicchio, some Rieslings… Little oxygen will preserve the ‘good’ sulfur compounds.... • ‘Bad’ sulfur compounds (Reduction) • Hydrogen sulfide • Methyl mercaptan … but too little oxygen could bring in the ‘bad’ sulfur compounds!!

6. Good guys and bad guys: 3MH and H2S/MeSH in Sauvignon blanc Outliers Wines bottled with high levels of glutathione and kept under no oxygen H2S+MeSH (mg/L) 3MH (ng/L) • A correlation exists • Some wines have a tendency to over-produce H2S and MeSH. In this case this was linked to the presence of a strong quinone scavenger such as glutathione. Lack of oxygen in the bottle will exacerbate this tendency

7. Winemaking and closureslection Partnership with AWRI 5 Reductive winemaking (inerted press, aging on lees, addition of glutathione) Non reductive winemaking 4 3MH (ng/L) 3 mg/L 3MH (ng/L) 2 This wine can lose varietal aromas rapidly… This wine retains high varietal fruity aromas, but…. 5 1 800 800 4 0 H2S 600 600 H2S 3 Methyl mercaptan Methyl mercaptan mg/L 400 400 2 200 200 … it also has a tendency to develop reduction …. but is less likely to develop reduction 1 More O2 to prevent reduction (Select 300) Less O2 to avoid loss of varietal aromas (Select 100) 0 0 0

8. Bad guys: Formation of methyl mercaptan (MeSH) in bottle Closure with low oxygen ingress (e.g. screw cap) MeSH (mg/L) Closure with medium oxygen ingress (e.g. synthetic or natural) Profiles of oxygen evolution in the bottle • Oxygen in the bottle stays at very low levels regardless of closure permeability • But we can see the outcomes of different levels of closure oxygen permeability

9. Origins of MeSH and link with oxygen exposure DMDS unlikely to be involved: its concentration does not change with oxygen exposure Higher MeSH with lower oxygen exposure mg/L Days mg/L Which precursors ? Lower MeSH with higher oxygen exposure Days Lower MeSH due to reaction with quinones Mercaptan trapping Catecol Quinone

10. Reduction Intensity 6 18 12 months • If a wine has a ‘reductive tendency’ , it will show typically between 6 and 18 months • Before 6 months it is not evident, but wine can be ‘closed’ with little aroma expression and aggressive palate • After 18 months it disappears in some wines, while some others keep unplesant aromas

11. Managing wine complexity Less oxygen More oxygen Methyl 2-methyl-3-furyldisulfide Benzyl mercaptan ng/L GC-O MF (%) Aldehydes MND Closure O2 permeability Shiraz Carmenere

12. Oxidative aroma compounds: Methional in Carmenere wines • Background • Storage at higher temperature increases the risk of oxidative damage • Methional has been identified as one key off-odor compounds in oxidized wines Partnership with PUC 7 6 5 Natural cork 15°C Select 300 15°C 4 ppb Select 500 15°C 3 Natural cork 30°C 2 Select 300 30°C Select 500 30°C 1 0 Methional concentration after 6 months • Conclusion • At low temperature methional concentration not different across closure types • At high temperature closure has an influence, and thighter closure allows lowering methional levels

13. Premature oxydation in red wines Influence of closure O2 permeabilty Partnership with AWRI and University of Zaragoza • Background • Premature oxidation in red wine is becoming a cause of concern in some winemaking regions (e.g. Bordeaux), with high intensity of dry plum off-odor • MDN (3-methyl-2,4-nonanedione) is responsible for these dry plums off-odors 5 4 3 Intensity of ‘developed’ character Aroma impact of MDN (GC-O) 2 1 0 1 1,8 3,6 O2 consumed after 18 months in bottle for a Shiraz wine in mg/L • Conclusion • Choice of right permeability allows controlling the risk of premature oxidation due to MDN (lower MDN at lower oxygen consumption)

14. How much oxygen? A matter of styleTwo Sauvignon blanc cases 0.6 mg/L of oxygen in 6 months 1.5 mg/L of oxygen in 6 months Yeasty/Cheesy Bitter Struck flint 0.6 mg/L oxygen consumed in 12 months Fresh green Yellow Overall fresh fruit Honey O/all fruit fl. Bruised apple Tropical 1.2 mg/L oxygen consumed in 12 months 2008 Sauvignon bl. Trained panel at AWRI 2011 Sauvignon blanc. Preference rating Wine journalists at 2012 EWBC • Relatively small differences in oxygen consumption seem to make a big difference in Sauvignon blanc • But not always the one receiving less oxygen is the preferred one

15. How muchoxygen? A matter of styleChianti Classico Riserva 2.9 mg/L of oxygen in 18 months 3.8 mg/L of oxygen in 18 months In this case we have a rather clear preference for higher oxygen permeability Preference rating Wine journalists at 2012 EWBC

16. A series of closures with defined and consistent oxygen ingress Defined values of oxygen ingress Batch-to batch and cork-to-cork consistency mg of O2

17. Selecting the right closure