Boyd on wine: Screw cap, cork or something else?

At one time there was no question about how best to close a wine bottle; you simply put a cork in it. Today, winemakers have more choices. Besides natural cork, the options include synthetic stopper, glass stopper and screw cap, to name the most common closures. Deciding which one is best to preserve the wine in the bottle involves such considerations as type of wine, cost of the wine and packaging, and perhaps, most importantly, the image presented to you, the consumer.

Where the bottle of wine is placed in a store or on a wine list may influence the sale, but even more important is the way the bottle looks on the shelf, the image conveyed by the winery that says, “Look no further, this is the quality wine you’re looking for.”

A big part of that image is at the top of the bottle. A savvy consumer will know by looking at the bottle that the smooth capsule dressing most of the time hides a natural cork.

At first glance, it’s easy to tell that most screw caps look like screw caps, even though recent attempts have been made to fashion the cap and capsule unit to look more like a traditional wine bottle capsule.

All bottle closures have their advantages and disadvantages, but two closures are by far the most popular choices and the ones generating the most chatter in the wine community. Natural cork, the stopper fashioned from the bark of a cork oak tree, is the traditional closure and, according to its legion of advocates, is the only choice. A more recent arrival on the wine scene, and one that is slowly growing in popularity among the wine trade and the buying public, is the screw cap, a closure more commonly seen on soft drinks and bottled water than wine.

Synthetic stoppers (so-called because they are not made of cork) have been around a bit longer than screw caps but these “plastic” closures have been slow to catch on with wineries or wine consumers. According to a recent survey by Wine Intelligence, a UK-based company that supports wine businesses worldwide, the growing legion of wine drinkers in China prefers synthetic closures over screw caps.

Cork oaks are found mainly in Portugal and Spain, with smaller forests in Sardinia and Northern Africa. The bark of a cork oak is harvested every nine years, making natural cork a 100 percent renewable, watertight and sustainable natural resource, an important advantage as the wine industry goes forward with a strong emphasis on sustainability. Portugal and Spain closely regulate the growth and harvest of their trees, to assure a continuous supply of corks for wine.

The major disadvantage of natural cork is that it is susceptible to “cork taint,” (commonly called TCA), caused by the presence of a mold that permeates the cork, giving the wine a musty or off smell and taste.

Recently, the cork industry has made gains at eliminating Trichloroanisole, or TCA, resulting in fewer corked wines today than a few years ago.

Amorim, the world’s largest cork producer, claims that it will eliminate cork taint by 2020. Nomacorc, another major producer of wine corks, recently released their Green Line of corks, made from sustainable sugarcane-based raw materials. Screw cap manufacturers, like the well-known Stelvin, claim that screw caps do not have a problem with TCA contamination and that they are both airtight and watertight.

And, proponents of screw caps point out that you don’t need a corkscrew with a screw cap. Plus, the unit cost for screw caps is lower than corks. Despite these advantages, screw caps have a lingering image problem with the wine trade and wine consumer. Lately, though wine professionals claim that more consumers no longer see a bottle of wine finished with a screw cap as being of lower quality.

Other known problems with some screw caps include reduction, the noticeable aroma of struck flint. Wineries that decide to switch to screw caps also face increased costs for different glass bottles, new closures and adding a new section to the bottling line. Some small wineries get around these costs by using a mobile bottling service.

There is no denying that industrywide, screw caps have the edge in Australia and New Zealand, where wineries have embraced the screw cap for all but their most elite bottlings. But the appeal for natural cork over the screw cap appears to be stronger than some reports claim. In a study done earlier this year, the Portuguese Cork Association and the Cork Quality Council claimed that 97 percent of those surveyed say that natural cork is an indication of wine quality and 91 percent said they preferred a natural cork in a wine ordered in a restaurant.

So, armed with those seemingly biased numbers, I conducted a little nonscientific survey of wines with screw caps to see if there was support for those survey results. Santa Rosa Bottle Barn has approximately 1,000 different brands of California wine on its shelves. Additionally there are hundreds more wines from a range of world wine regions. Wandering up and down the aisles, I noticed approximately 28 California white wines and 12 California red wines with screw caps. It would appear that California winemakers are still favoring cork over screw caps.

Wine Intelligence provided further support for natural cork in a 2016-2017 survey that showed 60 percent of respondents in the U.S., China and Germany still prefer natural cork. China, a country with vast potential sales but still shaping its wine tastes, was the most skeptical of screw caps, preferring synthetic closures over screw caps.

The bottom line question: Does a wine closed with a natural cork taste better than one with a screw cap? Perhaps the question will be answered soon when Oxford University researchers complete an experiment, using brain scan technology, to determine what differences closures like cork and screw caps have on the taste of a wine.

Meanwhile, wine consumers should rely on personal preference using price, winery reputation, image and a few general purchasing guidelines, such as that screw caps work well with white wines and light reds intended for early consumption, and natural cork works well for those red wines, high-end chardonnay and riesling.

Gerald D. Boyd is a Santa Rosa-based wine and spirits writer. Reach him at boydvin@sbcglobal.net.