Synthetic closures: practical solutions Maurizio Ugliano November 2012

Wine bottle aging Wine improves with a period of aging in bottle Sensory quality Time 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

Wine styles and market trends Less oxygen More oxygen

O2O2 O2O2 2 Roasted, smoky Simple fruity aromas Ageing time Aging with low O 2 Aging with high O 2 Complex black fruits, dry fruit, chocolate, tobacco, What is actually happening? Bottling Wine style Wine faults

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

Good guys and bad guys: 3MH and H 2 S/MeSH in Sauvignon blanc 3MH (ng/L) H 2 S+MeSH (  g/L) Outliers Wines bottled with high levels of glutathione and kept under no oxygen A correlation exists Some wines have a tendency to over-produce H 2 S 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

Reductive winemaking (inerted press, aging on lees, addition of glutathione ) Non reductive winemaking MH (ng/L)  g/L H2SH2S Methyl mercaptan H2SH2S Less O 2 to avoid loss of varietal aromas (Select 100) More O 2 to prevent reduction (Select 300) This wine retains high varietal fruity aromas, but…. … it also has a tendency to develop reduction This wine can lose varietal aromas rapidly… …. but is less likely to develop reduction Partnership with AWRI Winemaking and closure slection

MeSH  g/L) Bad guys: Formation of methyl mercaptan (MeSH) in bottle Closure with low oxygen ingress (e.g. screw cap) 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

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

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

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

Oxidative aroma compounds: Methional in Carmenere wines Methional concentration after 6 months Natural cork 15°C Select °C Select °C Natural cork 30°C Select °C Select °C ppb Background Storage at higher temperature increases the risk of oxidative damage Methional has been identified as one key off-odor compounds in oxidized wines 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 Partnership with PUC

Intensity of ‘developed’ character Aroma impact of MDN (GC-O) 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 O 2 consumed after 18 months in bottle for a Shiraz wine in mg/L Premature oxydation in red wines Influence of closure O 2 permeabilty Partnership with AWRI and University of Zaragoza Conclusion Choice of right permeability allows controlling the risk of premature oxidation due to MDN (lower MDN at lower oxygen consumption) ,83,6

How much oxygen? A matter of style Two Sauvignon blanc cases Yellow Overall fresh fruit Tropical Fresh green Struck flint Bruised apple Honey Yeasty/Cheesy O/all fruit fl. Bitter 0.6 mg/L oxygen consumed in 12 months 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 1.5 mg/L of oxygen in 6 months 0.6 mg/L of oxygen in 6 months 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

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

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 O 2

Selecting the right closure