Are there any scientific advantages to using a cork to stop a wine bottle?

Question

Although I am by no means a connoisseur (I don't really even drink it) I have been investigating the various means by which wine bottles are stopped up.

This was prompted by a negative reaction by a more dipsomanic friend to a screw top wine that I had purchased from my local off licence. The impression I got from him was that a bottle with a cork was less... tacky. And that somehow a bottle with a screw top gave him the impression of teens in parks drinking Lambrini through straws.

I have read a few articles online here, and here which seem to show some benefits to screw top bottles (namely that they aren't affected by TCA and are easier to open).

I have not been able to find any resources which show an actual benefit to the wine that comes from using cork. The usual pros listed include the fact that it supports natural cork plantations (an ethical consideration) or that it just seems to be more sophisticated.

So, is there any reason (when only considering taste) that cork should be used over a screw top?

Answer 1

If a wine maker loves their wine, and their customers, they will use screw caps. All the studies have come back positive for screw caps. See screw cap initiative for starters.

Some main points are:

• Corks taint the wine
• Corks, real or synthetic, have a very high failure rate. Screw caps are basically 100% effective (maybe too effective)
• Wine ages better with a screw cap, as there is no chance of seal failure or tainting
• Screw caps have been physically tested for over 30 years, and are designed to last longer than that
• You can cellar wine bottles at any angle
• The energy used in making a recyclable (aluminium) screw cap is significantly less than used in making a cork
• Most corks aren't made in ethical plantations
• No special tools are required to open and recap a bottle (cork knives can be a serious health hazard later in the evening).
• Wines age more safely. Corks do not breathe, but they may shrink and let wine out (bottles stored on side). Good vineyards will re-cork cellared wine every 20 to 25 years, or when corks start failing. The wine is topped up to the correct level, and often the wine/cork gap is flooded with nitrogen to avoid oxygen contamination which will "soften" the wine.

All in all, some pretty convincing reasons to go with screw caps.

Answer 2

An oenologist (a wine expert), once told me that for young wines, artificial corks (and probably screw caps) are perfectly alright. Young wines should be consumed within a year or two.

However, for aged wines, he'd stick with natural cork, because cork lets the wine breathe, letting the wine mature further inside the bottle.

The debate around synthetic is due to the fact that synthetic cork completely blocks the air. Some wine experts believe that some air is beneficial to the maturation of the wine.

source: http://www.cellaraiders.com/NaturalCorkSyntheticCorkScrewCaps.php

Edit: The cork bottled wine benefits from a process called 'reductive aging'. According to WineMaker Magazine, some wines need a little extra oxygen that seeps through the cork over a long period of time.

Although cork-stoppered wines intentionally allow for miniscule amounts of oxygen to seep in over a long period of time, amounts beyond this can prevent the proper development of bottle bouquet, and proper varietal aromas can also be obscured or destroyed.

Some wines are more affected by oxygen than others (i.e., wines that are low in acidity, body, tannins, etc. -- those traits that allow a wine to age extensively). A key factor influencing the potential oxidation of a given wine is its pH level. As pH rises (i.e., or as acidity falls), the potential for a wine's oxidation increases. When pH rises the wine's phenols are in a state that fosters their reacting to each other and falling out as sediment and increasing the wine's potential for oxidation. Therefore, wines with a higher pH have lower potential for aging than wines with a lower pH.

According to Wikipedia, the benefits of screw caps in this aspect have yet to be proven.

The advent of alternative wine closures to cork, such as screw caps and synthetic corks have opened up recent discussions on the aging potential of wines sealed with these alternative closures. Currently there are no conclusive results and the topic is the subject of ongoing research.

Answer 3

This is an awkward question, because food is about so much more than chemical interplay on the tongue, and how molecules decay over time. If all we cared about was getting proper nutrition, we would swallow a handful of pills each day which contained the nutrients we need, washed down with a shake containing bulkier elements like proteins and carbs. If all we cared about was taste, we would construct artificial foods with perfectly synthesized flavor profiles. (I'm guessing we'd wrap our perfect mix of nutrients into beverages, if flavor was the goal. After all, we already do have a host of artificial flavored sodas and such out there.)

But food is about so much more than that. Presentation makes food look engaging. Textures and smells have a huge impact on whether you find a food enjoyable. Wine glasses clink (particularly when toasting) to engage your hearing. The ceremony around uncorking a bottle creates a definite atmosphere which will color your perception of a meal, even down to how dishes taste. So, as easy as it may be to find links to articles about bottle seals and preventing air exchange, that is by no means the sum of the flavor in a bottle of wine. And anyone with experience of different dining environments, who enjoys uncorking a bottle, will find much changed in the flavor by the change from a cork to a screw-top. Yes, it's psychological. But really "flavor" is about how chemical impulses from your senses are interpreted by the brain; all flavor is psychological. And all of your senses work together; it's never about a simple signal from one sense.

Now, all that said, if you are NOT steeped in wine tradition, you likely will enjoy a glass of wine from a screw-top bottle perfectly fine. The fluid will be preserved at least as well, and if the only thing which changed in your meal was the un-corking became an un-screwing, a non-connoisseur probably wouldn't even notice. (Except all your "wine snob" friends will have a new topic for the next 20 minutes.) In wines produced to be consumed within 5-10 years, I highly doubt there is any worthwhile difference between any sealing method. And I doubt any of the wine collectors have allowed screw-top bottles into their collections yet, so we're still hundreds of years shy of long-term storage data.

I'll add that I had heard the common idea that cork is a depleting resource. This is often mentioned as a reason for the shift from corks to other closures in wine. I tried to Google this, and found several discussions (on semi-public forums, so I'll leave research to the reader rather than provide links) about this being a myth, and the shift being caused by a desire to prevent contaminants from getting into wine. So, it seems bottlers feel cork is a poor choice for wine.

Answer 4

So there's the science of aging wine, and then there's the neurology and psychology of drinking wine, and wines that we think are more expensive end up affecting our pleasure sensor more. In those cases, they told people what the cost of the wine was (well, lied about the cost).

Presentation matters with food. When people think they're being served something fancier, it affects their perception of it.

So ... if you're going to be serving the wine to someone by the glass, and they don't see you pour, the screw top is superior. If they see you open the bottle, and they're not familiar with the advantages of screw tops, cork is better.

I'm still waiting for someone to make a bottle that's corked + screw top. So you take off the better seal, but can still pull the cork out to impress those people that don't know better.

Oh ... and I should also mention that most people can't tell the difference in blind tastings of wine. If you enjoy your wine, you should do everything in your power to not become a wine connoisseur.

Answer 5

Your critical friend reminds of a scene in an old film where Fred Astaire, an American in Paris, complains that he's searched every local shop for a decent bottle of wine but can only find French stuff ...

Cork is the bark of an oak tree. A lot of the European supply comes from Catalunia, the region that is partly French and partly Spanish south of Perpignan. I've seen them taking the bark off there, they remove a large section around half the trunk, leave the tree alone for thirty years to grow more bark, then they take the other side off. This is not a crop that allows farmers to respond rapidly when demand increases. You have to plant trees for your grandchildren.

Decorative and insulative uses for cork, that were common 40 years ago, have disappeared - cheaper alternatives have been found. They may come back in the future, when new planting allows it. In the same way, the more enlightened wine producers have sought alternative closures for their short life wines, but they are still using corks on the top line wines.

The reason is that corks have a proven history of reliability as a closure, as long as the wine is in contact with the cork. A hundred year lifetime is not uncommon, if you have that much willpower. I have a record of Enrico Caruso that is over a hundred years old, it still plays. I have a CD of Paul Weller that is about twenty years old, but some of that doesn't play. OTOH I can drop a CD and most of the time it won't make a difference.

The demand for bottle closures increases and the cork supply is finite for the forseeable future. There is resistance to change, a lot of snobs don't like wine without a cork, especially in France and Germany where they have been accustomed to corks all their lives.

Cork doesn't improve the taste ...