As someone who has studied wine as a career, I freely confess that there is confusion and misinformation out there regarding the differences between a bottle of wine that is closed with a cork versus a screw cap. I have read texts and spoken to winemakers and tasting room hosts who offer outright conflicting information.
This article serves to shed light on the differences as best as I understand them based upon my own studies and observations from working in the hospitality and wine industry for 12 years. In places where I have come upon conflicting information, I have tried to offer opposing perspectives, inviting the reader to draw his or her own conclusions.
Corks have been used as stoppers for thousands of years. Cork material is a natural substance created by the bark of the cork trees that grow in the Mediterranean region. Because cork is a natural substance, its composition is not 100% reliable. It is accepted in the wine industry that about 5% of all corks will cause “cork taint” in a wine. This is a production fault that causes a stale flavour and a smell of wet dog, damp basement, or soggy cardboard. If 5% of all wines closed with a real cork will be faulty, why use cork to close a bottle of wine at all?
One reason is tradition. The ritual of opening a bottle of wine with a corkscrew is part of the experience, and in my opinion, adds a romantic element to the enjoyment of a bottle of wine. It is commonly accepted that closing a bottle of wine with real cork will allow the wine to benefit from further ageing as well. Real cork is porous, which means that it contains tiny holes. The holes are too small for the wine to come through, but they do permit a very slow ingress of oxygen into the bottle. Most textbooks and wine industry professionals that I have consulted are in agreement that this slow ingress of oxygen will facilitate further maturation of a bottled wine, permitting new and interesting flavours to arise with time. Wines that are closed with real cork should be stored on their sides so that the cork remains moist. If the cork dries out it can shrink and crack, which will allow too much oxygen into the bottle and result in spoilage.
Screw caps were brought into vogue in the last few decades in New Zealand and Australia. Traditionally these two countries were the last to receive a supply of cork from cork producers in the Mediterranean. The top quality cork would go to the wineries of Europe which enjoyed greater clout thanks to the prestige that came with their pre-eminence. The lesser quality cork would be sent to countries with newer, less established wine industries. Because of this, wines closed with cork in New Zealand and Australia suffered a higher rate of cork taint than wines in Europe. The Kiwi and the Aussies eventually tired of suffering this disadvantage and began using screw tops en masse.
I have spoken with winemakers in Niagara who have told me that screw tops differ from real corks in the respect that they do not allow an ingress of oxygen into the wine. This means that screw tops are a good choice for wines that are not designed to benefit from further ageing in the bottle. A common misconception among consumers is that all wines get better with age. This is not necessarily true because some wines are intentionally designed to be enjoyed when they are young, fresh, and fruity.
When it comes to top quality wines from New Zealand and Australia, these wine regions are regularly closing their wines with screw caps. The consumer base in these countries has accepted screw caps as a mainstay, while consumers from European countries still regard wines closed with screw caps as inferior. These differences in perception are merely a matter of prejudice and are not a genuine reflection of the quality of the wine inside the bottle. However, if top quality wines from New Zealand and Australia are being closed with screw caps, does this mean that the wines will fail to precipitate interesting flavours as they mature in the bottle?
My research has suggested that the jury is out on this. Some say that the small amount of air inside the bottle between the liquid and the cap is enough to facilitate further ageing. I have also heard it said that some newer model screw caps have been designed in such a way that they do allow a small ingress of oxygen. And I have also been told by some tasting room hosts that wines closed under screw cap do not benefit from further ageing in the bottle but will simply become “old.” So who to believe? In my evaluation, screw caps have not been used en masse long enough to properly assess if wines will improve with age if they are closed under a screw cap for over 10 or 20 years. To put it simply, more research needs to be done.
The wineries in Niagara are producing world-class wines closed in both screw caps and real corks. To learn more and to taste the difference, join a tour with Niagara Vintage Wine Tours. You will benefit from the experience and perspective of one of our knowledgeable Wine Smart Guides and meet a number of tasting room hosts who will be happy to share their perspectives as well. Call our guest services agents at 1-866-628-5428 for more information or to book a tour today.
Michael Twyman – Sommelier and Niagara Wine Country Guide for Niagara Vintage Wine Tours and Bootleggers