Capsules

[Derek T.]

I have often read about the critical role that a cork plays in the bottle ageing process. There are many references to the fact that a natural cork allows the wine to breathe due to the fact that air can pass through the cork. This leads me to wonder whether or not an airtight wax capsule above the cork inhibits this process. Is there any evidence that waxed and unwaxed bottles age at different rates?

Derek

[Tom Archer]

The 'breathing through the cork' rhetoric is 99% baloney.

If that was important, they wouldn't go to so much trouble to seal the tops of the bottles with foil and wax - or use stoppers with plastic tops.

Wine maturing in an airtight environment (i.e. in bottles) - evolves in what is called a reductive manner, whereas wine maturing in barrels, where there is some exposure to air as it permeates the wood is called oxidative maturation.

Maturation by the first process gives you VP and Crusted, by the second, aged Tawny's and Colheitas.

Combine the two maturation regimes, and you get LBV's and Garrafeiras.

Heresy though it may seem, the only likely downside to maturing VP under a screwcap is the risk of the aluminium cap corroding and failing over time.

Equally heretical would be the use of plastic corks. While these are utterly pointless for regular table wines when weighed against screwcaps, they probably have a much longer life expectancy than either cork or a screwcap, so might actually be quite practical for VP's.

However, unless some mysterious disease wipes out all the cork trees, it will never happen!

Tom

[Frederick Blais]

A good point that was made about regular cork is that even if no oxygen was coming from outside in the wine, there are some bubbles of oxygen as they put the cork on the bottles that are kept inside it and released over time. This may just be enough to age it gracefuly.

About the plastic cork, the problem with it is that it is not elastic. Put your finger in the neck of a bottle and you'll see that it is very uneven. The plastic cork does not fit these small curves so it let lot of oxygen going trough with time, spoiling the wine very quickly. This is now a common knowledge that starts to spread really quickly.

[Tom Archer]

About the plastic cork, the problem with it is that it is not elastic.

Err, they are - maybe the ones you've encountered were very hard - I doubt they're all the same. The few plastic corks I've seen seemed softer and more pliant than natural cork.

The amount of oxygen contained within a compressed natural cork is extremely small, and tiny compared to the amount that will dissolve in the wine during bottling, so I'm doubtful that could have a detectable influence.

The fact that new corks have a slight taste and smell of their own indicates that natural cork contains some transmittable elements (TCA being one...) that may have some influence on maturation.

Tom

[Andy Velebil]

There was a topic about this on another forum and basically synthetic corks are great for short term storage, but have issues retaining the seal and becoming hard or brittle after a number of years.

Fred is also right, synthetic corks only work well in bottles that have very straight necks with uniform sized interior walls. A synthetic cork can only expand just a little to fill those gaps in. A natural cork can expand quite a bit (think of a champagne cork and how far it expands) and fill in those irregular shaped necks.

Wax is also helpful to protect the cork from drying out (Derek, remember the resaon for the one waxed Port bottle on Thursday). Although you don't see it done much anymore, but I guess better year-round storage exist now so wax is really a thing of the past and not seen much anymore.

They also wax old bottles to help protect the cork and reduce possible oxigen from getting past the old cork. But wax is not 100% airtight.