For wines, synthetic stoppers and screw tops are not significantly better than traditional corks

While most wines in 750-milliliter bottles have corks in them, the number of bottles that have screw caps is significant.

A few decades ago, screw caps were reserved for the lowliest of wines, and the wine-consuming public assumed any wine that had a screw cap was pedestrian, the sort of stuff fit for a brown paper bag and a nearby gutter.

But back then most wine professionals knew that screw caps had certain advantages over traditional corks, which were susceptible to an invisible mold that had an unpleasant aroma.

Between 2 percent and 10 percent of all wines closed with traditional corks were affected by the mold, called TCA. And solutions were elusive.

At first, many wineries switched to synthetic stoppers. Some looked like traditional corks, while others were colorful. And when they were hastily pulled, the synthetic corks made a popping sound.

But while synthetic corks didn’t develop TCA, some of them were exceedingly difficult to remove from the bottle, and it might take a pair of pliers to unscrew them off of the corkscrew. It took a decade or two, but the producers have figured out how to avoid these problems.

Meanwhile, screw caps were gaining ground. In particular, around 2000, the New Zealand and the Australian wine industries embraced screw caps for many of their wines. Most American and European wineries sat on the sidelines, waiting to see what would happen.

In general, things worked out very well for the screw cap enthusiasts. Today, the best estimates are that almost 15 percent of all wines are finished with screw caps. Even more successful are the synthetics; perhaps more than 30 percent of wines have synthetic corks in them.

At first, I was eager for an alternative to traditional cork and frustrated by the slow pace of the traditional cork industry to end the epidemic of cork taint. When you’ve paid $100 for a very special bottle of wine, saved it for 10 or more years, gathered friends to share that bottle and the only thing you smell is moldy newspaper (that’s what TCA does to wine), well, you’d be angry, too.

But it turns out screw caps weren’t perfect.

They were too good a closure; they sometimes created wines that seemed starved and depleted, or they developed some odd smells of their own. The reason? That tiny bit of oxygen present in the fissures of a traditional cork had a beneficial effect on wines. So, just as those synthetic corks have changed and improved, the screw cap itself had to adapt.

Screw cap producers came up with super-thin liners that allow very tiny amounts of oxygen in. The simple twist and turn of a bottle of Ripple is now the product of amazing research into “gas permeability” and “oxygen ingress.”

It’s not just techno-mumble; the new screw caps mimic the tiny amounts of oxygen that traditional corks allow to seep into a wine, albeit at a glacial pace. For the moment, things look pretty rosy for screw cap producers again. Most in the industry are predicting continued and robust growth. If nothing else, a wine with a screw cap is easier to open and easier to re-close.

Things have changed at the traditional cork factories as well. Even though they haven’t been able to completely wipe out TCA, the incidence is much lower.

Not that I can boast any great scientific studies (well, I could, but none of them seems to agree on anything about TCA), but in my own practice, I probably open or test more than 5,000 bottles of a wine a year. Where once I expected to find a tainted bottle in every case, I’ve now often opened five or six cases of wine before I find a bottle with noticeable TCA.

My attitude has softened. I believe the wine industry has an opportunity — moreover, it has a responsibility — to be as green as possible. The wine business can be extraordinarily green. Responsible water and wastewater usage, no pesticides or herbicides, proper land use, and lighter and less wasteful packaging are areas the wine business is addressing.

Where do traditional corks fit in? They are harvested from century-old cork oak trees (which re-grow their bark repeatedly) in ancient and protected forests, many along the otherwise condominium, hotel and casino-ridden Mediterranean coasts. If the cork industry dries up and is replaced by synthetics and screw caps, those forests don’t stand a chance against the developers. I believe that screw caps and synthetics have their purpose, but I’m not planning to give up on traditional corks anytime soon.