Even in the early antiquity knew the Assyrian. Egyptian and Greeks the cork. In some cases, cork stoppers were also used as closures for vessels such as amphorae used. Mostly, however, pegs made of terracotta (clay) were used, which were fastened with string and then sealed with lacquer, clay or pitch. The Roman author Cato the Elder (234-149 BC) writes that the wine jugs after the fermentation would have to be closed with cork and pitch. The Romans already knew this type of closure, but it was forgotten again with the fall of the Roman Empire. This was probably because the Iberian Peninsula as the main source of cork bark was conquered by the Moors in the 8th century and ruled for a long time. Until the late Middle Ages, vessels were sealed with wooden plugs dipped in oil and wrapped with hemp, pitch or wax.
With the development of glass bottles Glass plugs were primarily used first, but the cork was rediscovered at the beginning of the 17th century. Even the monk and alleged inventor of the champagne cathedral Pérignon (1638-1715) experimented with it. The corks initially had a conical shape due to different bottle neck sizes and were only half-sunk for easier removal. Only by developing more usable corkscrews they got a cylindrical shape and were now driven fully into the bottle neck. As the dominant type of closure for bottles The cork then established itself in the middle of the 17th century, which subsequently led to a rapid boom in the cork industry.
Today, the natural cork is mainly made from the thick, outer bark of the most suitable cork oak "Quercus suber". More than half of the world's production comes from Portugal, and other important countries are Spain, Algeria, Italy and Morocco. The trees reach heights of up to ten meters and can be used for around 200 years. They can only be peeled for industrial use at the age of 25; The bark is only suitable for bottle corks from the age of 45. This is done again at intervals of 9 to 12 years; A tree can be debarked about 15 times. The bark is aged for at least one year, then boiled in water, pressed, cut into plates and sorted by quality.
Strips are cut from this, from which the cylindrical plugs are punched out. They are produced in a length of 38 to 60 mm; longer corks usually mean a higher wine quality. The blanks are smoothed on the end faces and rounded. This is followed by bleaching and impregnation with a wax-like substance to make the cork slippery. Finally, the cork brand, today this is mostly an imprint. When packing the cork is often for preservation sulfur added.
A natural cork is an almost ideal and also undisputed in terms of aesthetics an optimal closure for wine and sparkling wine bottles. It is light, clean, relatively insensitive to different temperatures, is rarely rotted, is healthy, is impermeable to air, extremely elastic and has a long lifespan of usually 10 to 20, in exceptional cases 50 years and more. The cork cells are impermeable to gases and water due to the storage of suberin (waxy pulp). In each bark (bark) there are places with so-called Lentizellen (for gas and water exchange). As few as possible are of advantage for the quality of a cork. A normal wine bottle cork has a diameter of 24 mm and is compressed to the bottle neck diameter of 18 mm. However, even after years of bottle storage after being drawn, it returns to its original size after 24 hours.
The humidity must be high enough so that the cork does not release any moisture into the environment (ideally 75% at 10 ° C). Like all organic substances, however, a cork loses its suppleness and thus its ability to close with age. It is therefore advisable to drink a bottle with a broken cork in good time or to re-cork it. A few wineries offer their customers the special service one Neuverkorkung for very old bottles of their best products. With extreme temperature fluctuations, the cork can leak; which is prevented by even temperature. Can on the cork Weinstein crystals deposit, which can lead to a certain impairment in terms of tightness.
A frequently asked and discussed question is whether the wine “breathes” through the cork when it is stored or whether and to what extent oxygen for the development of the wine during the bottle aging or for the durability is required. The small amount in the bottle neck may be enough, but today this space is mostly with inert gas filled or a vacuum created when closing. Natural corks are compared to other alternative closures such as conventional ones Plastic corks or screw caps permeable by a factor of three or four. Recent research on AWRI (Australian Wine Research Institute) have shown that there is a controlled supply in the smallest quantities, i.e. in a more even manner OTR (Oxygen Transfer Rate) very positive flavorings and colour especially from red wines. However, the amount required depends, among other things, on the vine, So that would speak for the natural cork, but in the meantime there are alternatives closures with which you can control the oxygen supply individually.
Pressed corks (also composite corks or agglomerate corks from agglomerat = agglomeration) are not cut out of the cork oak in one piece, but are cork granules bound by resin or glue. These are significantly cheaper than natural corks. As a rule, a piece of two to three mm long normal natural cork is applied to both sides so that the wine does not come into direct contact with the glue. Such types are referred to as “1 + 1 corks” or “2-disc corks”. Press corks are mostly used for young wines. They are considered less storable because there is also a risk of crumbling.
A sparkling wine cork is often split into two for cost reasons. While the upper part (head) consists of pressed corks, two discs of natural cork are glued on at the bottom, which are in direct contact with the sparkling wine stand. Because of the opposite one Still wine There are some special features here to ensure that the cork is fixed at a much higher pressure within a sparkling wine bottle. Sparkling wine corks are also cylindrical, but much thicker. The diameter of an uncorked sparkling wine cork is usually 30.5 mm and its length 48 mm. When inserted into the bottle neck, the cork is compressed to 19 mm, which results in a much stronger seal and the typical mushroom shape in the upper part protruding from the bottle neck. The cork also comes with a Agraffe (Wire mesh) fixed, whereby a small metal capsule (plaque) protects the cork from being cut by the wire.
At a champagne the text "Champagne" must be on the cork Millésime (Vintage champagne) also show the year. After removing the cork from the bottle, its shape also reveals something about the duration of storage (usually a sparkling wine should be enjoyed as soon as possible). If it goes with the lower part (foot) in width, it is called "Juponne" (jupon = petticoat) and the bottle was probably corked less than a year earlier. A narrow foot is a "Cheville" (cone), which means corking back in time.
Today, because of the enormous demand, corks of increasingly poor quality (large pores) come onto the market. Either they are leaking or due to the porosity oxidative Processes and, in extreme cases, to leak the wine. Due to unclean cork production, too corked arise. The closures that are therefore actually ideal would be alternatives like that screw cap, Quite a few mock it, miss the "pop" and complain of a loss of culture, but this development is probably over ecological and unstoppable for economic reasons. In addition, the often used pro argument for the "plop" as a sensual pleasure is not valid, because a bottle should be opened silently. Almost 60% of the world's wine bottles are currently closed using natural corks. See also under closures,