April 17, 2019 – The debate over cork vs. other types of closures has been roiling the wine industry for about half a century. And it still goes on. A recent piece in Forbes by Thomas Pellechia described three separate tests in Europe and the U.S. illustrating that the jury is still out.
The Romans used cork over 2,000 years ago to seal wine jars, painting them with pitch to make sure the air stayed out. Cork as a stopper got lost in time and bottles and jars were sealed with cloth, leather, clay or wax. Some time in the 17th Century, Europeans began to use corks to seal wine bottles. We know that Dom Perignon’s bottles had corks and there’s a story that he got the idea from Spanish travelers who used cork to plug their water gourds. Others dispute this story so the history is a little hazy to say the least.
Interestingly, the British invented the corkscrew in the 1700s, which was a big advance on using a musket-cleaning tool to dig them out.
Cork is a natural product being the bark of a cork oak. It is not recyclable but it is biodegradable. It seals bottles efficiently and keeps the air out but allows enough oxygen to seep in very slowly so that red wines in particular benefit with a little air softening the tannins as they age. So what’s all controversy? Unfortunately, a natural, harmless compound called trichloroanisole (TCA) can affect corks tainting the wine and this happens to about 3% to 5% of wines in the bottle. When a wine is “corked” it smells moldy or like dirty socks if the taint is really bad. Small amounts can be present in award-winning wines detectable only by instruments but not consumers according to California’s Wine Institute For many of us it can be hard to tell if an unpleasant “nose” is TCA if it is faint. A consumer can’t be blamed for thinking this is what a certain wine tastes like, drinkable but not one to buy again, and that’s bad for the winery and the brand. If it is really off, then the wine gets discarded as undrinkable. In a restaurant, a customer can send the bottle back but it is harder if it happens at home. Some retailers will work with the customer and take a bad bottle back but all this is a hassle.
Imagine if other consumer goods such as soup or soda had a failure rate of 3% to 5%. Consumers would stop buying it and the product would fail. So winemakers have been looking for suitable substitutes for cork. But the funny thing is, wine drinkers are steeped in tradition and have set expectations about how their wines should be packaged as tests show.
So what are some of the trending new closures and what are the pros and cons?
Synthetic corks made from plastic compounds that are molded or extruded, look like corks and need a corkscrew for removal. They don’t suffer from TCA or “cork taint” but some people with really good palates do detect a chemical flavor in older wines.
In their favor synthetic corks solve the cork taint issue and they are a fraction of the cost of real cork, which is a great advantage for the producer, especially of lower end wines. However, they can be a bad fit allowing air into the bottle oxidizing the wine and turning it into undrinkable vinegar; they cannot expand and contract with temperature fluctuations as natural cork does which is critical for aging wines; they are often really hard to remove; and because they don’t allow any oxygen to seep in they can’t help a wine age gracefully. So oxygen is both a friend and an enemy of wine and it all comes down to how much. A tiny bit very slowly is great. A whole lot is disastrous.
If the wine is going to be drunk soon after purchase – and a 2018 survey by Sonoma State University of 1,191 wine consumers from 50 states found that wine is consumed within two weeks of purchase – then aging ability isn’t an issue. Technology continues to improve and a new closure made from leftover fibers of sugar cane compares favorably against both natural and synthetic corks. The company, Nomacorc, producing this closure offers varying degrees of oxygen ingress so that a winemaker can choose the specific closure for a wine that is expected to be aged for 5, 10, 15, 20 or 25 years.
Screw caps have cut into synthetic cork’s market with more than double the global market share at 45%. Australia and New Zealand have been leaders in replacing natural cork. According to The Sydney Morning Herald of June 28, 2017 “The genesis for the switch can be traced to the 1970s, when cork shoes were in fashion. Back then, international designers had first pick of Portugal’s best cork supplies, for which they paid a premium.” The winemakers were left with inferior quality cork and that led to problems.
A small band of winemakers in South Australia’s Clare Valley decided to experiment. They worked with the Australian Wine Research Institute for more than two years to test nine different closure methods. Screw caps were judged the winner. They all released their 2000 vintage Rieslings under screw cap. Now 99 out of every 100 bottles of Australian wine are sealed with screw caps.
In 2001 in New Zealand, a group of around 30 wineries, including many prominent ones, decided screw caps were the future with The New Zealand Screwcap Wine Seal Initiative, a sort of manifesto and promotional vehicle.
In the U.S., about 50% of wines are sealed with screw caps. Even though many premium wines, especially whites, are now sold with screw caps, the perception lingers that screw caps imply lower quality wines. This was borne out in a recent study by Washington State University with 310 participants. Each person had four placemats each with a photo of one of four different closures marked A, B, C, and D. They also had four wine glasses. Two different red blend wines were poured. How the wines were divided between the four glasses was not explained. The wine served in the glass on the placemat with the photo of a natural cork closure was rated significantly higher than the other three which were synthetic cork, screw cap and a glass stopper. The latter came in second as a premium wine. Glass stoppers are popular in Europe but hardly used here due to cost and expensive refitting of bottling lines.
The conclusion, of course, was that consumers perceive wine sealed with natural cork to be better wine. This is the usual result of such research.
Studies have also been conducted on the sound of corks popping out of the bottle versus a screw cap being unscrewed. You guessed it. The popping sound indicated the wine was better.
New Zealanders claim
There is consensus that screw caps offer superior protection to white wines keeping them fresher with virtually no deterioration or flavor changes between bottles. This is a good thing. The New Zealanders claim they work equally well on reds but as yet, screw capped reds haven’t been around long enough to validate whether or not they can age well. We’re talking 20 years plus. Several respected wine writers agree that red wines fare well also after tasting wines that are 10 years old.
Chateau Margaux’s experiment
The Wall Street Journal reported just this week on a tasting of wines from the famed Chateau Margaux’s experiment with closures other than cork. Ten years ago they bottled generic red and white wines sealed four different ways – natural cork, two kinds of screw cap, one being airtight and the other permeable, and a synthetic cork. The latter was described as “absolutely catastrophic”.
The writer, Will Lyons, favored the red wine bottled with the airtight capsule saying it tasted more polished and silkier than the other two. The vintage was 2003 so it showed well after a good number of years. But Chateaux Margaux’s wines last many decades and this experiment will go on for 100 years. Stay tuned!