Cork and the History of Wine Bottle Closures
Cork is derived from the bark of the *cork oak* (Quercus suber), a tree found primarily in the Mediterranean regions, notably in Spain and Portugal. The use of cork dates back to the 4th century BCE, when Egyptians employed it for making fishing floats. Although the exact time when cork was first used as a wine bottle stopper is uncertain, archaeological evidence points to corks found on Roman shipwrecks dating as far back as the 5th century BCE. However, its use for sealing vessels was not widespread at the time.
The collapse of the Roman Empire significantly impacted global trade and the use of cork. Between 500 and 1500 CE, cork production in the Iberian Peninsula dwindled as demand decreased, and its use gradually disappeared. The resurgence of cork as a wine bottle closure occurred in the 17th century, and over the last four centuries, it has become the primary method for sealing wine bottles. However, starting in the 1970s, alternative closures began to emerge due to concerns over cork taint caused by 2,4,6-trichloroanisole (TCA). This chemical compound, formed by the interaction of plant phenols, chlorine, and mold, imparted an undesirable musty odour and taste to wine, prompting a search for new solutions.
The Historical Use of Cork and Wine Closures
During the Greek and Roman eras, cork was valued for various practical purposes, including sealing wine casks. Detailed writings from Greek scholars describe advancements in viticulture and disease control in vineyards, as well as the use of cork for making stoppers. Archaeological discoveries of Roman amphorae from 500 BCE to the 4th century CE show evidence of cork seals, though these were often reinforced with resin to enhance their sealing properties. Unlike modern stoppers, these early corks were rudimentary and required additional materials to ensure tight closure.
The decline of the Roman Empire ushered in the so-called Dark Ages in Europe, which saw a dramatic decrease in trade and innovation. The demand for cork dwindled, and cork producers struggled to find buyers. Additionally, the spread of Islamic rule across parts of Europe, where alcohol consumption was prohibited, further stunted the cultivation of vineyards and the use of cork. For nearly a thousand years, wine was stored without the use of cork, with methods such as a layer of olive oil or primitive cork held in place with string being used to reduce oxidation.
Cork imports to England began in the 1300s, but it wasn’t until the 1500s that it gained traction as a wine bottle stopper. In the 17th century, wine was primarily shipped in barrels and decanted into glass carafes for serving. This changed in 1632 when Sir Kenelm Digby introduced technology for manufacturing strong, affordable glass bottles. Early glass bottles were hand-blown and varied in size based on the glassblower’s lung capacity. At that time, corks were inserted into the top of bottles, protruding for easy removal, as corkscrews had yet to be invented.
The advent of affordable bottles in France and the 1703 Methuen Treaty between England and Portugal boosted cork production. The 18th century brought design changes to bottles, transitioning from bulbous shapes to cylindrical forms that allowed for horizontal storage, keeping corks moist and airtight. The patenting of the first corkscrew in 1795 completed the evolution, marking a significant turning point in wine history by enabling aged wine consumption.
Cork Taint and Technological Advancements
The expansion of new wine regions in places like Australia and New Zealand in the late 20th century increased demand for cork. Reports of entire batches of cork contaminated with TCA became common. Often, protective wood treatments containing chlorine used on ship decks reacted with mold-covered corks, forming TCA. This chemical taint, and its variant tribromoanisole (TBA), is created when plant lignin degrades in the presence of chlorine and mold, leading to a musty aroma that ruins wine quality.
By the late 1980s, frustration over cork taint led to the exploration of alternative closures, spurring innovation within the cork industry. One significant breakthrough was Diam, an alternative closure made from natural cork broken into granules and treated using a patented supercritical CO2 DIAMANT process. Supercritical CO2, which exists between a gas and liquid state under specific temperature and pressure conditions, can penetrate cork and remove TCA compounds. Though supercritical CO2 technology was already used in industries such as decaffeination and nicotine extraction, it took seven years of research to adapt it for cork processing.
The DIAMANT-treated cork granules are reassembled using food-grade binders and microspheres, ensuring elasticity and structural integrity. This method guarantees TCA-free corks with no off-flavours or potential contaminants. Diam’s commitment to sustainability is evident in its efficient use of resources. Unlike traditional corking that discards excess material, Diam repurposes every part of the cork bark, maximizing its use and minimizing waste.
