Cork or Screw Top?

What is cork?  Why did it become synonymous with wine and why, after all these years, are screw tops (sometimes referred to as Stelvin closure) threatening to steal the cork's thunder?

According to Wikipedia, cork is an "impermeable, buoyant material, a prime subset of bark tissue that is harvested for commercial use primarily from the Cork Oak, which is endemic to Southwest Europe and Northwest Africa."  Portugal is the highest producer, with 61.3% of annual production and 32.4% of total cork forests.

Because of the near impermeability of cork, it has made a name for itself as the perfect bottle stopper (until recently?)  Natural cork closures are used for about 80% of the 20 billion bottles of wine produced each year - much more palatable than the oil-soaked rags stuffed in the ends of wine bottles that French Vintners used in the 17th century!

(http://wineandfoodmusings.wordpress.com/category/australia/)

When the tree reaches 25 to 30 years and 24 inches in circumference, the cork can be removed for the first time.  Cork is extracted only from early May to late August, when the cork can be separated from the tree without causing permanent damage.  However, the first harvest almost always produces poor quality or "male" cork.  Cork can be extracted at intervals of 9 years, subsequent to that first time, though it can take up to 13 years for the cork to reach an acceptable size. If the resulting cork is of high quality, it is known as "gentle" cork, and, ideally, is used to make stoppers for wine and champagne bottles.

(http://www.naturalhomeproducts.com/cork_flooring.html)

How long has cork been used as a wine stopper?  According to one web site, an amphora from the 1st century B.C. was found to not only have a cork closure, but contained wine!  It seems that cork has been a well-liked and extremely effective for a long time!  Not to mention ALL the great crafts and home decor that has resulted from corks that have been removed!  So HOW is it possible that, after all this time, cork could end up being replaced by the screw top?

(http://sutterhome.com/blog/2011/03/who-do-you-love-cork-or-screwcap/)

The "screw top" wine closure is becoming increasingly common among wine producers.  It is a metal cap that screws into the threads on the neck of the bottle, usually with a metal skirt down the neck to resemble the traditional wine capsule.  A layer of plastic, often PVDC, cork, rubber or other soft material is used as a wad to make a seal with the mouth of the bottle.

The Stelvin Closure, is the brand name of the most well know brand of wine screw top.  This brand was developed by Rio Tinto Alcan in the late 1960's or early 1970's.  It is such a common brand that it has been genericized in common use.  The use of screw tops is on the rise in New Zealand and Australia.  In New Zealand alone, use of screw tops went from 1% in 2001 to 70% in 2004.

In comparison to cork closure, screw tops prevent the wine faults of oxidation and of cork taint, and are easier to open, although there are questions about long term aging.  However, cork closures are viewed as higher end and has a well known characteristics that have been established through years of experience.

http://blog.friendseat.com/screw-cap-stelvin-vs-cork/

For me, while the convenience of a screw top is evident, I still love collecting corks and, when applicable, writing the special occasion on the side of the cork.  One cannot argue, however, with the ultimate goal of protecting the wine with the most effective method possible.

Interestingly, other that for wine, cork is also used as the core for baseballs, in the friction lining material of clutches, and are hung from hats to keep insects away.

I am not sure corks will ever be phased out completely, but it is evident that screw tops can no longer be associated only with less expensive wines and, I suspect, this trend will continue to grow.

Cheers!
Mary Jo

Wine Word of the Week

malolactic fermentation - a chemical conversion of acid by beneficial bacteria. During the process the sharp, malic acid is converted to a softer lactic acid. It can add to the "buttery" character of wine as well as add complexity. All red wines go through malolactic fermentaion, but with white wines it depends on the winemaker. The winemaker may induce this process to develop a softer mouth feel in the white wine. If the winemaker wants to maintain a bright acidity, the process would not be induced.