In the world of wine, cork is king. With an estimated 7% annual growth in U.S. sales, natural corks made from evergreen cork oak trees are about twice as popular as any other closure, and not just because they seem somehow classier than the alternatives. Primarily grown in Portugal and Spain, cork oak bark has a honeycomb cell structure, which allows flexibility and encourages the material to bounce back into its original shape. More importantly, the slightly porous nature is also ideal for aging wines, allowing a low level of oxygen to gradually permeate the bottle and change the wine over time.
Cork trees take about 25 years to grow to maturity, at which point they may be stripped of their bark once every nine years. From the harvested bark, cork stoppers are punched out and sorted for quality. The remaining bark is then ground and recomposited to create economically priced aggregate corks. These days, however, corks are not winemakers’ only option. Read on to learn about some of the alternatives to natural corks and benefits and drawbacks associated with each.
Image by Mark Ihrig
Generally, synthetic corks provide a lower barrier to oxygen than natural ones. High-end synthetic corks, however, can now be designed to specifically mimic the oxygen transfer rate of natural corks. In fact, Nomacorc, the largest producer of synthetic corks, even sells products according to oxygen transmission. Unlike natural corks, synthetics are not at risk for cork taint, a condition that negatively affects about 2 to 3% of wine. Also, because synthetic corks are manufactured rather than grown, there is less variation from cork to cork.
Image by Mark Ihrig
A food-safe plastic liner sits inside an aluminum screw top, offering a virtually perfect seal, great for wine meant to be drunk fresh with no extra tool required for the drinker to access the liquid within. Screw tops aren’t suitable for aging wines for more than a year, though.
The vinoseal, essentially a glass cork with a rubber seal, looks more like a decorative stopper than the alternatives, and it’s easy to dislodge without an opener. And much like a screw top, the vinoseal offers a practically perfect closure thanks to a rubber seal. This means wines closed with a vinoseal should also be drunk within a year.
Better known atop beer bottles, crown caps can be a good solution for bubbly. Often, sparkling wines that will later be corked go through secondary fermentation with a crown cap; some producers decide simply not to change over to a cork and cage for the finished product. Like screw tops, crown caps are best for wine meant to be drunk fresh, and lack the celebratory “pop” that accompanies the dislodging of a natural or synthetic cork.
Beyond the choice of how to seal a bottle of wine, winemakers are increasingly turning to alternative vessels entirely, giving the standard glass wine bottle a run for its money.