Thank you everyone for another great discussion on natural wine last week. Although it's a topic we come across frequently, there's a lot of great information to be had on the thread. Decide for yourself!
This week: Closure
How do corks compare to stelvin and other types of wine bottle closures, and why may a winemaker choose one over the other?
Some of the differences are obvious. You run the risk of cork taint when using corks. And although it is a natural, renewable resource, that makes them susceptible to factors like temperature and humidity. On the consumer side, you need a wine key to open a traditional bottle. For wine on the go and by the glass options, a stelvin closure is an easy option. You can reseal it much more securely than putting a cork back in.
Tecnical corks were invented to limit the effect of TCA. Companies began making agglomerated corks treated to prevent the bacteria. These corks are effective and also prevent leakage. They're ability to age wines is expected to be as effective as traditional corks.
Screw caps are easy to produce and provide a close, air-tight seal for the bottle. They also handle temperature and humidity better cork style closures. They don't require the bottle to be stored horizontally to keep the cork moist. But many find these closures are better for wines meant to drink young. Cellaring a bottle with a stelvin closure doesn't allow for that small amount of oxygen to penetrate the wine as a traditional cork would. Also on the downside? The connotation of a wine with a screw cap. It's not uncommon to present a bottle to a table with a stelvin closure and receive a few raised eyebrows in return.
Vino seals, or glass caps, offer many of the same benefits that stelvin closures allow, look neat, and are reusable. But they're much more expensive to make and also require a specific bottling machine.
Finally, synthetic corks made of plastic compounds and biopolymers offer an affordable closure option and still provide the experience of pulling a cork. The top products also ensure a consistent oxygen transfer rate for aging wines. For marketing purposes, the material also lends itself to better labeling than traditional cork.
I want to believe that non-cork closures age a wine beautifully, but the texture more than anything is a turn off for me. In my experience, screwcap covered wines with age don't have the textural richness of cork covered wines, despite similarly developed flavors and aromas. Jamie Goode talks about his experience here: www.wineanorak.com/.../comparing-the-same-wine-sealed-with-cork-and-screwcap
That said, this is really only a big problem when the wine reaches a decade or so. Since the vast majority of wine will never be laid down that long, closure matters less. At that point, the discussion switched to aesthetics. Do consumers care? At a certain price level, in the same way that wax is a selling point at a certain price level. (Does the wax affect the aging- guess that's part of this discussion, too, if a little less important than the closure type).
The sales pitch of screwcaps is that the technology is there to regulate varying flows of oxygen, not eliminate it. Pretty much the same with all of the alternative enclosures.
Cost is another consideration that winemakers look at. Corks cost more than most alternatives, and there is even a wide range of pricing even within the natural cork offerings.
Dominique Lafon also spoke recently on the IDDT Podcast about the variability and susceptibility to TCA between corks from the same producer in the same batch, as well as their permeability and potential to expose the wine to oxygen, which is one of the reasons that he has made a move towards using DIAM corks.