For nearly four centuries, cork has been used to seal virtually every bottle of wine. Since the 1970s though, that dominance has come under attack from other types of closure such as screw-caps, plastic seals and glass stoppers. Each year, 20 billion closures go into wine bottles and then 10-15 years ago increasingly they were not natural corks.
Cork is one of the most mysterious and most wonderful creations nature has made - nature’s perfect product. Cork is very light in weight, this is why it’s very first use was to make fish floats and buoys. Cork has been used for about 4000 years. Though as a way to seal wine containers, it has been used for about 1000 years - from 500 BC to 500 AD. Then for 1000 years, it was stopped as world trade collapsed after the fall of the Roman Empire.


About 1600 it came back into use, and it has been the dominant closure for up to 400 years. Cork is biodegradable and also recyclable, - plus the use of natural cork is consistent with certified-sustainable vineyard and winemaking practices. There are several factors which have prompted wineries to return to natural cork: Effectiveness: As the closure protects the integrity of the wine. Natural cork is significantly more reliable than it was. No closure is perfect, but recent research and testing has shown that natural cork can once again be a choice. Ease of Extraction: natural cork can be removed from a wine bottle with relative ease. Appearance: Well-made natural cork does not look plastic or cheap, it looks timeless and refined.
The cork industry in Portugal has made positive improvements to natural cork, especially in the reduction of TCA. With better tracking of the cork-bark from the forest to the final punching of the corks. Better storage and sanitation of the production plants monitoring the washing cycle - complete reduction of chlorine used for bleaching-sanitizing corks, plus better humidity control and improved TCA analysis. 
With more than a decade of research and effort - TCA contamination is down to virtually nothing, though there are still a few fears and concerns. With cork, oxygen is diffused out over six months, then stops. Natural cork works with inevitable imperfections in glass bottle necks, as cork is more forgiving. Studies have shown as much as 80% of oxygen problems in wine are actually born on the bottling line.
Despite all the work that has gone into the reduction of TCA in natural corks, the very nature of natural corks is accepting some small level of TCA will be present in a batch of corks. Overall, the level of TCA detected in trials by Davis University is below 1%. Yes the industry wants perfection. Wineries demand the very best closure. Part of the value or wine is that the consumer knows they are getting the very best without compromise.
But better consistency, and higher technical quality can again make natural cork a serious competitor in many markets. Better natural corks have also forced other closure makers to raise their game, which winemakers and wine consumers certainly benefit.
Many wine markets prefer natural cork: The USA, France, Italy and Spain are some of the countries which remain faithful to cork. The perception of quality associated with this natural closure is common to the majority of consumers surveyed. In the USA, a study carried out by ‘Tragon’, published in 2012, found an overwhelming 94% of respondents said they would be more likely to buy wine with natural cork.
In Spain, loyalty to cork is a significant 92% of consumers (study carried out in 2012), within the framework of the 'Cork Project'. Results show that 86% of Spaniards believe that the cork preserves the quality of wine and Cava better, compared with artificial closures.
Italy still has a confidence that the best closure to protect the quality of wine is the cork. It is the preferred choice for 85% of consumers surveyed in 2011 by the market research company 'Demoskopea'. 83% consider the protection of the environment important and 77% the quality factor, and 88% also recognise it as a recyclable product.
In France, a study by ‘Ipsos’  in 2010 showed that nearly 90% of consumers and nearly 80% of industry professionals prefer cork closures. They recognise the contribution cork makes to the wines maturation process and believe it is better at preserving aromas compared with screw-caps or plastic closures. From the general public in French, 96% of those interviewed associate the cork with tradition, 90% feel that cork preserves the wine's aromas and 90% do not hesitate when choosing between a cork and another closure. Germans prefer cork because they believe that the wine is high quality and associate the cork with sustainability and ecology.
Today in the USA and Europe, the choice for sustainable packaging is of increasing importance for consumers and retailers. In this field, no other closure is able to compete with cork, a completely natural material, which is biodegradable, renewable and recyclable and requires very little energy to manufacture, 4-5 times less energy than artificial closures.
A study conducted in 2008 by 'PricewaterhouseCoopers' analysed the life cycle of cork closures and assessed the possible environmental impact of three types of wine bottle closure options: corks, aluminium screw-caps and plastic closures. In 6 out of 7 environmental indicators analysed, the cork demonstrated that it was the most efficient, appearing in second place only in terms of water consumption. Cork stoppers are the only closure with a positive impact, not just because they have a smaller carbon footprint. If we add this to the important role of the ecosystem of the cork oak forest in repossessing CO2, preserving the species, combating desertification, there is a positive impact associated with the use of cork.
Greenhouse gas emissions for the production of corks are 24 times lower than for aluminium closures and 10 times lower than those made of plastic. Wineries which use cork may reduce from between 18% - 40% of CO2 emissions from their wine bottles, which means that this is a good option for wine producers, distributors and retailers who aim to minimise their carbon footprint and adopt best practices in regard to environmental performance.
If there is one area where cork closures would seem to have an unavoidable disadvantage over screw-caps, however, it would be convenience. Screw caps are easier to handle and with rising technical quality, that would seem to give it a big advantage in some channels.
In 2013 Amorim released a screw-cork closure called Helix - (see images). The cork and specially-made bottle are designed so that the cork screws into and out of the bottle. Helix won the top product - ‘Best Green Launch’ - at the 2015 Drinks Business Green Awards in London that recognise and encourage environmental responsibility and sustainability. Helix’s appeal lies in its convenience and ease of opening, while also achieving all the sustainability credentials of natural cork. This unique Helix system is a possible game changer for Amorim and other wine cork producers.
The Twin Top® cork closure (by Amorim) is based on the technology behind the production of the champagne cork. It meets winemakers’ demands while retaining all the benefits of a natural cork closure in terms of sustainability. It is made of an agglomerated body with a disc of natural cork at each end.
The introduction of these better quality cork closures, has broadened the range of cork options designed for different market segments. Corking closures can also cope with wider temperature fluctuations during the day, as other metal closures can expand and loose their integrity. For storage they can be stacked higher vertically than screw-cap closures, which after 4 cases high the weight can damage the seal of the cap in the bottom cases, plus other benefits.
So don’t be surprised if you find your favourite winery or wine label returning to use cork in the near future on some of their wines. As with any industry - it is great for the producer to have improved research and product developments which benefit all - and options to safely seal their wines for different channels and styles.