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  • Myths and Curiosities

Cork Myths and Curiosities

Did you know that a single cork stopper can capture up to 562g of CO2?

And that cork was used in Ancient Egypt and can be used to produce energy? Did you know that scientific research consistently proves that consumers associate cork with high-quality wines?

Find out everything you’ve always wanted to know about cork.

Cork’s success over centuries lies in its unique physical properties that no man-made closure has been able to replicate: lightness, compressibility, elastic memory, gradual recovery, impermeability to liquids and resistance to wear, heat and rot.

Cork also allows a minute amount of oxygen to permeate into the wine after sealing. This appears to have a beneficial impact, but more research is needed to understand the full contribution of the cork to wine development.

In addition, the introduction of technical corks such as Twin Top, champagne corks and Neutrocork has extended the range of cork products available to suit each wine style and market segment.

With proper handling during and after bottling to ensure the best performance, cork is unsurpassed as a wine closure.

Cork remains as relevant today as it has ever been. Producers such as Amorim have effectively defeated the problem of TCA and are working constantly to improve performance.

New research is helping us better understand the unique contribution that the cork makes to wine development. We will be able to use that new knowledge to further improve our products.

We do not accept that a single closure can cover every single wine segment. Amorim is developing new corks products to suit specific wine segments, responding to a specific need in the wine market. Our closures range from natural corks to Twin Top corks for premium wines and Neutrocork for the popular premium segment. All meet high standards of sensory performance and consistency.

The cork industry has made great improvements in sensory performance, especially in the last five years, and new initiatives such as the communal cork processing facility will allow smaller producers to take advantage of the most recent advances in cork processing technology.

However, it is true that not all producers meet the standards achieved by companies such as Amorim.

By buying from an accredited supplier such as Amorim and by implementing their own quality control procedures, winemakers can buy cork confident there will be minimal risk of TCA.

Cork stopper production is at the heart of the cork economy; without it other uses of cork would become unviable. The forests would fall into neglect. It would be harder for farmers to resist pressures to clear the forests for more profitable uses such as eucalyptus.

It is true that the cork industry as a whole was too slow in responding to the problem of TCA. That has all changed and a huge R&D effort is devoted to improving cork quality.

The emergence of alternative closures was a wake-up call to the cork industry. Competition has been good for quality.

The problem of TCA in cork has been effectively addressed, while problems with alternative closures persist; in fact, screwcap proponents are in denial about the problems being encountered.

There is enough cork in Portugal to meet demand for the next 100 years. Under a large-scale re-forestation program funded by the EU the forests are growing by 4 per cent a year. High quality cork forests in North Africa (Algeria, Tunisia and Morocco) are being brought into commercial production.

Most importantly, the introduction of high quality technical corks is allowing much better utilisation of the cork resource.

Amorim produces high quality closures to suit each market segment and price point and believe cork-based closures are very competitive. In fact, in some markets cork closures such as Neutrocork can cost half of the current prices for leading oil-derived stoppers

Given the importance of the closure to the wine after bottling, winemakers are encouraged to ensure they purchase a high quality closure. Amorim commercial personnel can advise on the most appropriate closure for each wine.

Winemakers may make recommendations, but they cannot control when a wine is to be drunk. They must be confident that the closure will last the distance, regardless of when the wine is to be drunk. Cork has proven itself to be an effective seal on wine stored for decades. Technical corks such as Twin Top, which are designed for short-to medium-term cellaring, are still performing well in comparative trials, even after 5 years.

Winemakers can use cork confident in the knowledge that it will perform well, regardless of when the wine is to be drunk, without the risk of premature oxidation or sulphide-like odours associated with other closures.

Wines may not need oxygen to develop, but it appears that they benefit from the minute amount of oxygen ingress allowed by cork stoppers.

Where wines have been totally deprived of oxygen, i.e. in glass ampoules, they have also displayed a marked tendency to develop suphide-like odours. So evolution may continue to occur, it just so that it leads to results that are far from what the winemaker originally intended.

The findings of researchers at University of Bordeaux 2 suggest that oxygen diffusion through the natural cork is more important than reported by J. Ribéreau-Gayon in 1933.

"Ribéreau-Gayon used a similar colorimetric method, but did not record the characteristics of the closures, the bottles or the storage conditions, factors that Lopes et al. believe would help to partially explain some of the differences between the results of the 1933 and 2005 studies."
Nancy Mills, "Sealing Themes And Variations", Article in Aust. Wine Industry Journal, October 2005

Post-bottling wine chemistry is a very complex issue and we are still a long way from understanding all the factors at play let alone controlling them for each wine style, region and vintage. Cork, on the other hand, has been doing a remarkably good job for centuries. As we understand it better we are able to further improve its performance.

"To try and make one extremely low permeability closure to suit all wines is going to lead to variability of results not between individual bottles, but wine to wine.… To require wines to be completely free of any sulphide precursors will place demands which at this point in time we are unable to (and may not wish to) consistently fulfil as winemakers."
A. Limmer, "Do Corks Breathe? Or the Origin of Slo", Aust. & Nz Grapegrower and Winemaker, Annual Technical Issue 2005

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