It’s been over ten years now since the humble screw cap was widely reintroduced as a closure for Australian wines, so we wanted to revisit the great debate about screw caps versus cork today to see how they’re stacking up and whether the claims about screw caps are still supported.
One of the most frequent questions we’re asked as winemakers is whether or not screw caps are better closures than cork. We also find that lots of people think screw caps are great for white wines, but that reds, especially those designed for ageing, can only ever reach their full potential under cork.
As winemakers, we put our heart and soul into perfecting our wines right through from picking grapes to the final bottling, and we nurture and coddle them all the way. But once the wine is in the bottle we lose all control of how the wine develops. For us, it’s very important that when the bottle is opened it’s in the condition we intended when it left the winery, not afflicted by the ravages of cork taint.
So what exactly is cork taint?
Conservatively, at least 10% of wines bottled under cork are considered “corked”, in other words they’re affected by cork taint, an undesirable character caused by a fungal-meets-chemical reaction occurring within the cork. This results in the compound known as 2-4-6-trichloroanisole or TCA.
TCA manifests in such delightful odours as wet dog, wet hessian, mouldy cardboard, damp basements and the like – I think you get the gist – just what you want to pair with that delicious twice-cooked duck breast you just ordered! And TCA at low levels is almost more of a concern than it is when it’s really rampant. Low levels of TCA often simply dull the fruit flavours causing many of us to write off a great wine because it just didn’t taste that good – even though the culprit was actually the cork, not the wine.
Other cork problems
But TCA is just the tip of the iceberg. Many wines (perhaps even 100% of wines bottled under cork) are in some way affected by the corks. The corks themselves can “scalp” fruit characters, flattening and dulling the wine and imparting a corky, woody flavour, especially obvious in whites. And as cork is a natural substance, there will always be some amount of variation and inconsistency from one bottle to another.
“There is no such thing as a great old wine, only a great old bottle.”
Enter the screw cap
One of the best things about screw caps is the reassurance that each bottle of wine will look exactly like the next one, and the wine will be presented to you exactly as the winemaker intended.
Screw caps eliminate almost all closure-related taints in wine including TCA, glue taints from agglomerate corks, plastic taints, which can often be picked up from plastic corks, random oxidation and corky, woody flavours from the corks themselves. Although the occasional taint may still sneak through with screw caps, the incidence is more like one in a million bottles rather than one in ten.
Screw caps and ageing
Screw caps provide a near-perfect, airtight seal whereas corks allow small amounts of oxygen to penetrate over time. It’s sometimes thought that because oxygen is unable to penetrate the screw cap, the wine cannot age. This is a fallacy. Wines do age under screw cap – all wines.
Oxygen, while it does act as a catalyst for ageing, speeding up the process, is not required to age a wine. Many corks allow in so much oxygen that they significantly oxidise the wine during bottle ageing prematurely turning it brown and obliterating the fruit (think of the browning that takes place when you cut an apple).
Screw caps allow the ageing process to take place without oxidising the wine, meaning the wine ages gracefully with more vibrancy, freshness and consistency than a wine aged under cork. Wines aged under screw caps seamlessly integrate the natural fruit with complex bottle development characters, making for a better drink over a longer period of time.
Screw caps and cellaring
Screw caps are much more forgiving of cellaring conditions. Wines bottled with corks need to be laid flat to keep the cork moist whereas wines under screw cap can be stored upright for any length of time. Corks expand and contract with fluctuations in temperature, but the robustness of screw caps means they’re far more resistant to temperature change. Screw caps are also resistant to humidity and odours.
Screw caps and convenience
Last but not least screw caps are easy to open – there is no need to have a a cork screw handy, you can take a bottle anywhere, and if you don’t drink it all you can reseal the bottle and take the rest home. And once you’ve finished, both the bottle and the aluminium screw cap are fully recyclable.
My personal opinion? Well I'm not a winemaker or an expert; but doesn't what this article says make SENSE? It does to me. If nothing else, wines with screw caps are a hell of a lot easier to store, and a hell of a lot easier to open. That's not everything; but it's something.
What do you think? I'd love to hear the other side. Are there any "corkies" out there?