Natural Cork vs. Screw Cap: Which Is Better?

There is an impression in the marketplace that a Stelvin (screw cap) closure on a bottle of wine infers a wine of less quality and value. Is it true or a misunderstanding? What does the bottle closure really do and what are the differences between the two? Why does it matter?

First, let’s look at what a bottle stopper does for wine. Wine is made up of water, alcohol, sugar, phenolic compounds and acids. It is the winemaker’s purpose to bring these components into balance. If too much oxygen gets in too quickly, it will decrease the fruity aromas and flavors found in that wine. It will also impact the color of the wine – darkening white wines and lightening reds. It is the job of the stopper to moderate the amount of oxygen that gets into the bottle over time.

One of the main measurements for closures is the Oxygen Transfer Rate (OTR). That, most obviously, is the measure at which the closure allows oxygen in through the stopper. Today, it has become a standard measure associated with a stopper for wine, whether it be cork, glass, or synthetic. Controlling the amount of oxygen is important to maintain freshness and allow the wine to evolve in proper time.

The real question though is why bother with something that works well and is associated with the ritual of opening a bottle? That pop sets the tone for a festive occasion, not like the crackle of a twist off cap. The main concern about natural cork for the wine industry is a mold from the cork that can contaminate the bottle of wine. The mold interacts with other compounds to generate a chemical called TCA, or 2,4,6-trichloroanosole, which impacts the bottle of wine. The common term used is the bottle is “corked.” Cork taint will, at the very least, mute the flavors and dull the aromas. At higher levels, it will smell like a dank, moldy basement. It is one of the reasons that you need to smell the wine and taste it to ensure the wine is good. Today, incidence of cork taint has fallen to low levels based on the great attention by the industry.

Screw caps are not associated with TCA, and that is one of the prime reasons vintners have been experimenting with different closures. Manufacturers of screw caps will provide closures based on the OTR desired by the winemaker. Most frequently, you will find screw caps on wines that are crafted to be drunk young such as Sauvignon Blanc or Rosé. Yet there are many wineries experimenting and putting some of their big reds in screw caps to see how the wine ages. The picture depicts some excellent wine: Cade, a big mountain Cabernet, and Siduri, an ageable Pinot Noir. Both are bottled with screw caps.

Do not be deterred from bottles based on the closure. Cork or screw cap deserve your attention and taste.