Corks
have been used as bottle stoppers for as long as we have
had wine. The Greeks in the fifth century BC sometimes used
cork to close wine jugs. Following their lead, the Romans
used corks as stoppers, adding a pitch to seal the closure.
Corks, however, did not predominate in those days. The most
common closure for wine jugs and amphora was a coating of
pitch or gypsum over the opening of a vessel and a film of
olive oil floating on the surface of the wine (to minimize
oxygen contact with the wine). The use of corks was apparently
abandoned completely in medieval times. Paintings from that
era depict twists of cloth or leather stopping a jug or bottle,
sometimes with sealing wax used to make a secure closure.
The marriage of cork and bottle took place during the first
half of the seventeenth century. The alternative closure
of the time, stoppers (stopples) of ground glass made individually
to fit each bottle neck, held its own for a remarkably long
time. As late as 1825, these stopples were still the closure
of choice. Eventually, these glass plugs were abandoned because
they were nearly impossible to extract without breaking the
bottle. One thing remained problematic in cork's widespread
use as a practical bottle closure: an implement that could
be driven right into the cork and easily extracted along
with the cork. The first mention in print of the instrument
now know as the corkscrew was in 1681. It was described as
a "steel worm used for the drawing of corks out of bottles." This
handy tool had been in use 50 years for drawing bullets and
wadding from firearms (and was originally called a bottlescrew.) "Corkscrew" was
not coined until 1720.
The Source of Cork
Quercus suber is the botanical name for a kind of slow growing,
evergreen oak that flourishes only in specific regions of
the Western Mediterranean world. This tree requires a great
deal of sunlight and a highly unusual combination of low
rainfall and somewhat high humidity. The quality and thickness
of the bark vary according to a tree's specific growing conditions.
Cork evolved as the tree's spongy protection and insulation
from, in particular, fire. Most trees die if their bark is
removed, because bark helps to carry sap that is essential
to the tree's life. The cork oak, however, has two layers
of bark. The inner layer is alive and is the base on which
a new inner layer grows each year. As the old layers move
outward and die, they serve as growing areas. The dead outer
layer can be stripped away without injuring the tree, but
care must be taken not to penetrate the inner living bark.
The first harvest of cork cannot take place until the tree
is 25 years old. Cork from the first harvest is irregular
in size and density and is not suitable for wine stoppers.
It is usually used for floor tiles or sound insulating materials.
Nine years must pass before the tree can be harvested again.
Even cork from this second harvest is not good enough for
wine bottle stoppers. It is not until the third harvest --
when the tree is 52 years old -- that the regularity of size
and density of cells renders the material acceptable for
wine bottle use. A cork tree generally yields between 13
and 18 useful harvests in its lifetime.
The cork bark is stripped by hand with the aid of small sharp
axes, and the resulting cork strips are then stacked and
weathered. The tree itself is carefully marked and numbered
so future harvesters know when a particular tree can be harvested
again.
Once in the factories of Portugal for processing, the cork
is stacked and aged an additional three months to let it
weather and dry. Proper moisture content is crucial for the
elasticity and compressibility of the cork. After this drying
period, the cork is immersed in boiling water for at least
90 minutes to sterilize it and to enable it to flatten from
its original curved tree trunk shape. After boiling, the
corks "ripen" for three to four weeks in order
to achieve the desired moisture level. Next, the material
is trimmed into strips, and holes that match the size and
shape of the bottle cork are punched into it. This stage
of the manufacturing process requires a keen eye as the hole
punchers maneuver the strips for maximum quality. Next, the
cork heads are polished so that the cork will have a specific,
uniform length. The body is also polished so it will have
a specific, uniform diameter. It should be noted that the
width of the bark strip forms the diameter of the cork, not
the length. Thus growth rings of the tree are to be found
imbedded longitudinally within the cork. The corks are then
washed and dried. Most are bleached in either chlorine or
hydrogen peroxide in order to disinfect it and rid it of
remaining impurities. Some are rinsed without bleach, depending
on specific wineries requests. Corks are graded for quality,
and branded with the purchasing winery's name. A final surface
treatment, either silicone and/or paraffin or a resin, is
sprayed or tumbled onto the cork's surface. This treatment
eases insertion into the bottle and improves the seal against
the glass. The corks are then bagged in plastic and shipped
to their final destination.
There's a Problem
Corkiness -- a condition that rears its ugly head when wine
is tainted by the presence of a chemical compound called
2,4,6- Trichloroanisole -- TCA for short. This compound appears
to be caused in the cork by interaction of moisture, chlorine
and mold. From the harvest of the cork to the bottling of
the wine, the cork can be exposed tothese three elements,
and TCA can form. The human nose can detect this corkiness
at concentrations as low as four parts per trillion. A lightly
corked wine may simply smell like cork, while a badly corked
one may smell musty, like damp carUser_ACB23Card or old newspaper.
The usual rich aroma and flavor of fruit and oak is stripped
away by the musty odor. A corked wine poses absolutely no
health problems -- it just doesn't smell or taste good. The
ultimate problem lies in the fact that good money has been
spent on a bad bottle of wine, and there is absolutely no
way of knowing this until the bottle is opened. A reputable
vendor will replace a tainted bottle.
Cork Alternatives
About six percent of
the wines submitted for review to Wine X Magazine suffer cork-related
defects. So why does the industry continue to use a faulty
closure device?
The revered tradition of cork as a wine bottle stopper will
die hard and slowly. Even though many find the use of cork
an elitist holdover that renders opening a bottle a difficult
and esoteric process -- as is the intimidating ritual of
cork sniffing in restaurants -- the image of screw caps still
conjures up images of "cheap wine." So what is
the answer? There are plastic, synthetic corks made of ethylene
vinyl acetate, trademarked as Cellukork. These closures look
and feel similar to real cork and require a corkscrew for
removal. However, there are two drawbacks: one is that Cellukork
often fits so tightly in the bottle that it is very difficult
to remove -- a problem sure to be resolved through research.
The other potential concern is whether the synthetic material
truly remains non-reactive and inert over long periods of
time. Will it impart flavors to the wine? There are obviously
concerns for those who cellar wine over a long period of
time. Wineries experimenting with these plastic corks are
deliberately aging wines to see what happens, but it will
be several years before outcomes are known.
So we turn back to the screw cap. It provides an excellent
air-tight seal. It is very consumer friendly – no more
struggles if you forget the corkscrew. It also gives wine
a down-home feeling by removing the intimidating "elitist" image
with which it is so often associated. Thus screw caps can
make wine more accessible, both figuratively and literally.
The problem? Again, aging. There is a question as to whether
screw caps protect wine over a very long period of time.
As yet, no conclusive tests have been conducted. But the
major problem is that many quality wine producers -- sensitive
to the fine wine market -- hesitate switching to a screw
cap because they do not want their product to be perceived
as inferior quality. Again, this is only an image problem
created by the industry itself.
The Answer
Because of worldwide concern with the perceived degradation
of cork quality and the tremendous impact it has on the cork
industry, a group of U.S. cork suppliers founded the Cork
Quality Council (CQC) in 1992. Its mission is to improve
the quality of corks at the source, to build an educational
program to assist wineries and to develop industry standards
for cork quality. And research with synthetic corks continues.
Many wineries are now experimenting with these plastic closures
and, if no problems manifest, many more will probably follow
suit.
Regardless of what closure a bottle of wine contains, the
ultimate experience should come from the wine itself. Whether
we pull a cork, twist a cap or access that wonderful nectar
through some other means, the most important thing is the
quality and enjoyment wine brings to everyday life.
Les Kincaid is a food, wine, and golf expert
and cookbook author: "Never Trust A Skinny Chef II."
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