To Cap or Cork?

Wine Corks

Celebrated Wine expert Ron Kapon, who is known in wine circles as the Peripatetic Oenophile —the traveling wine expert — answers your questions.

CHEESE CONNOISSEUR reader There seems to be so much controversy about wine corks these days. Some people tell me great winemakers only use real corks and other people tell me that screw tops are now being used for great wine. Why are winemakers using cork anyway?

R.K.: The Greeks used corks as bottle stoppers since the 5th century B.C. The Romans coated corks with pitch to seal the closure. However, in those days, the most common closures for wine jugs and amphora were a coating of pitch or gypsum over the opening of a vessel or a film of olive oil floating on the surface of the wine.

In the early 17th century, the closures of choice were stoppers of ground glass made individually to fit the bottleneck, but most wine bottles used wooden stoppers. By the mid-17th century glass bottles were being made with uniform openings, making cork the most practical and affordable bottle closure.

Cork is light and resistant to moisture penetration. Cork retains its properties at both high and low temperatures and will age without deterioration. We can thank the French monk Dom Pierre Pérignon, who swapped the wooden stoppers in use in the mid-17th century for cork stoppers and forever changed the wine industry.

screw caps

CC Reader: Cork must have been pretty exotic. Where does cork come from, and how is it harvested?

R.K.: There are more than 5.4 million acres of cork forests worldwide with 32 percent in Portugal and 22 percent in Spain. Cork grows well in the western Mediterranean because the trees require a great deal of sunshine, low rainfall but high humidity. Cork trees reach maturity around their 25th year. After that, the cork is stripped from the trunks once every nine years. It seems unbelievable, but the trees can live more than 200 years.

A cork tree will yield between 13 and 18 harvests in its lifetime. May through August is the time period during which the cork can be removed from the tree without causing permanent damage. The cork oak has two layers of bark. The inner layer is alive and will regrow every year. The old layers serve as insulation, protecting the tree from the heat. The dead outer layer can be stripped away without injuring the tree.

CC Reader: I guess the cork tree is pretty amazing, but how is it used to make a cork stopper?

R.K.: First, only the highest quality cork is used for wine and Champagne bottles with the first few harvests producing poor quality cork. A very sharp axe is used to make both a horizontal and a vertical cut. It is important not to damage the tree, or it will die. The cork is stacked and left to dry before being shipped to a processing plant. The cork is stacked for an additional three months to let it weather and dry.

After drying, the cork is immersed in boiling water for at least 90 minutes to sterilize it. The cork then ripens for an additional three to four weeks before it is trimmed into strips and holes are punched to create the correct size and shape.

The corks are polished, washed, dried and bleached in chlorine or hydrogen peroxide to clean and disinfect. Finally, silicone and/or paraffin or a resin is sprayed onto the surface. This improves the seal against the glass. The corks are then bagged in plastic bags and shipped to wineries.

CC Reader: That sounds very complicated. I’ve been hearing about synthetic corks. What are they? Are they as good?

R.K.: The allure of synthetic corks is that they are similar to natural cork: they fit the same bottles and can be removed the same way. Winemakers like them because the quality is more consistent and since cork is a natural product, the price and availability can fluctuate from year to year.

As a consumer, it’s a good idea to have another wine stopper on hand because if you don’t finish the bottle, it is very difficult to put a synthetic cork back. They can also be a little more difficult to remove. They are really a tight fit!

As for the wine, synthetic corks are just as good or better but there is still a lot of debate whether they are as good for the long-term storage and aging of fine wine. In the meantime, don’t worry about it if your wine comes with a synthetic stopper.

old etching of cork harvesting
Old etching of cork harvesting shutterstock

CC Reader: I see screw caps on lots of wines now. A screw top used to be the symbol of a cheap wine. Sort of like the wine you drank in your freshman year of college. Can you get good wine with a screw top?

R.K.: Australia and New Zealand use screw caps for a majority of their wines that are made for early consumption. Screw caps form a very tight seal and can keep out oxygen (the enemy of wine) for a longer period than cork. They also preserve the aromatic freshness of wine. The problem is that after 10 years or so the plastic in the caps may become brittle and allow air to enter the bottle.

Consumers still perceive screw caps as being for ”cheap” wines. However, a recent study showed that screw caps allow the lowest amount of oxygen permeation when compared to natural or synthetic corks, and protect best against the oxidation of the wine. They are also user friendly in case you forget to bring a corkscrew to the picnic. The bottom line is that a screw cap no longer means cheap, bad wine. I think you are going to see more good wines bottled with screw caps.

CC Reader: How about boxed wines? Are you going to shatter my love of corks again?

R.K.: A box wine is a wine packaged as a bag-in-box. They contain a plastic bladder protected by a box, usually made of corrugated fiberboard. The process for packaging “cask wine” (box wine) was invented in 1965 in South Australia. All modern wine casks now use some sort of plastic tap, which is exposed by tearing away a perforated panel on the box.

It is far less expensive, lighter and more environmentally friendly than bottled wine and far easier to handle and transport. Wine in a bag is not touched by air and thus not subject to oxidation until it is dispensed. Cask wine is not subject to cork taint or spoilage due to slow consumption after opening and can stay fresh for weeks after opening. They are not intended for cellaring and should be consumed within a year.

The bottom line is: how the wine is enclosed — natural or synthetic cork, screw top or bag-in-a-box — is less important than the wine itself. CC


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