Cork industry invests to remove musty taint

Published by Sally on May 16, 2009

A version of this article first appeared in the Drinks Business, December 2006.

2006 marked the ten-year anniversary of the Quercus Project. Its findings and report arguably marked a seismic shift in the sensibilities and responsibilities of the cork industry. The extent of reformation and revolution in the cork industry in those ten years was wide-reaching, and still continues. 

It feels as though we’ve known about TCA (2,4,6 trichloroanisole – the chemical compound that causes ‘corky’, or more accurately musty/mouldy taint) forever, but when Quercus was being put together in the early 1990s, it was not known if TCA was one of a range of agents responsible for off flavour, a minor player, or the main culprit. Quercus demonstrated how TCA could be formed, and that it was indeed the villain of the piece: 80% of musty/mouldy taints implicated TCA. The cork industry knew definitively where to focus attention and investment. Before this, it had been thought that taking chlorine out of cork manufacture would solve the TCA issue, until it was later realised than chlorine is ubiquitous.

But the cork industry was only just beginning to consolidate into a more vertically-integrated structure. Antonio Amorim, chairman of APCOR, (the Portuguese promotional body for cork) said: in the early ’80s, the cork business was configured so cork manufacturers were completely separated from the reality of the market. There was a clear separation between cork manufacturers and cork distributors, the latter being in touch with bottlers and having access to wine requirements. It was not clear that any technical issues raised at the time were in fact technical issues, but rather commercial, negotiation issues.” He added: “In the ’80s we were concerned with the physical and mechanical properties of cork stopper. It was only from early 90s that some larger manufacturing companies began taking control of importers/distributors in the consuming markets and by the mid 90s vertical integration was taking effect; we were dealing with winemakers regularly, getting feedback and access on a direct basis.”

So Quercus set out to identify the agent(s) responsible for off flavours; to identify what stages in manufacture these agent(s) were generated; to produce a strategy for cork stopper manufacture, and to produce a protocol and control measures for cork stopper manufacture. Essentially Quercus undertook a hazard analysis of cork manufacturing. Sofia Afonso, one of APCOR’S technical experts, said: “we can consider Quercus was the first step for developing control methods for TCA.  It was the first time people began to talk to each other in scientific way. It was one of the foundations to control methods and research for several studies that followed.” 

It’s most immediate success was the drawing up, through CELIEGE (the European Cork Federation), of the International Code of Cork Stopper Manufacturing Practices (ICCSMP). Though a voluntary code, it was the first attempt to lay down best practice in cork stopper manufacture, across different producing nations.  The ICCSMP code is now in its fifth edition (2006), with protocols updated to reflect new best practice, for example, cork stoppers not to be transported with materials likely to contaminate them.

This was followed, in 2000, by Systecode: a third party accreditation system that audits companies working according to the ICCSMP.   It’s estimated that more than 90% of cork stoppers are now made according to the code.

Sainsbury’s were one of the original partners of Quercus.  Howard Winn, their quality manager for beers, wines and spirits at the time, said “the cork industry realised it was watching its market disappearing. The Quercus Project was a good starting point. It catalysed a raft of things. Some of its recommendations were fundamental things which weren’t happening before.” 

By focusing on critical control points in the manufacture of cork, Quercus identified ways to eliminate and minimise risk, some of them very basic: not using the bits of cork bark nearest the ground as these to have the highest incidence of TCA; eliminating from stopper production cork planks contaminated with ‘yellow stain’ (which had a high concentration of TCA); keeping cork planks off the forest floor, and off bare ground; removing treated wood from the manufacturing process, for example, replacing wooden pallets with metal ones; and controlling the water used during the boiling phase.

Martin Hall director of food science at Campden and Chorleywood Food Research Association Group, and the original Quercus Project co-ordinator, said: “Quercus laid the foundations for technological development and innovation especially with boiling processes.  Innovations in boiling processes have largely removed the need for post-boiling stabilisation. Planks are now racked so there is less compression, significantly reducing the amount of water taken up into cork. This has reduced the amount of time for post-boiling stabilisation.  Also, water is re-circulated after each boil [to remove volatiles such as TCA extracted from planks,], etc. The process is now largely in the 21st century.”  Passing the water through heat exchangers ensures the temperature is a constant 98-99°C throughout the hour-long boil, where previously it had been a static system – no circulation, dropping water temperature, no removal of volatiles from the water.

Over and above this have been proprietary innovations occurring later in the manufacturing process – DIAM and ROSA are the obvious examples. Brand-specific extra cleaning and processing technologies which remove even more volatiles compounds.

Hall believes the key things over the last decade have been “the acknowledgement and acceptance of the issue, and one that could be dealt with, and the foundation given by the Quercus Project with the boiling processes and the code of practice.”  He singled out Antonio Amorim as a prime activator of change saying change would not have happened without such visionaries.

In the immediate aftermath of Quercus, both the Altec (Sabate, now Oeneo) and Twintop (Amorim) brands or cork closure were launched. Even before Altec met its demise, Oeneo were working on supercritical carbon dioxide. Dean Banister, their commercial director, said: “investment with supercritical carbon dioxide started eight years ago. Capital investment was completed in 2000: research, the pilot plant and validation, and getting the technology right. It took two to three years to adapt supercritical technology to suit cork, getting the ratio of pressure and temperature correct for cork rather than coffee.”

The Natural Cork Users Group convened early in the new millennium – an ongoing technical dialogue targeted to drive down levels of mustiness in wine. The group addresses itself to international standards, quality improvements, and the exchange of expertise, and counts over 60 members of technical experts, trade representatives and research personnel. It was the first time that the supply chain – retailers, industry associations, technical institutions, and the cork industry – came together in a technical forum with the intent to work together.

The frontiers of technical research and innovation in cork continue to be pushed. Scientific research is ongoing in some two dozen or more institutions in a dozen or so countries, all of which developed work since Quercus reported. Barrier technologies such as Procork have been developed; management and control of closure permeability are high on the agenda of all closure manufacturers; new types of technical cork binding materials are being researched; the idea of cork as a positive flavour contributor, like oak, may not be so far away.  Banister said: “supercritical has identified another 180 compounds that it extracts such as vanilla, terpenes, benzenes. By adjusting pressure and temperature and time we can leave in x and y.  TCA comes out pretty fast, other compounds take longer to extract.”

Quercus found TCA was involved in 80% of musty/mouldy taints. That still leaves 20% coming from sources other than TCA. We now know some of these are TBA (2,4,6-tribromoanisole), and TeCA (2,3,4,6-tetracholoroanisole). We also know the omnipresence of chlorine has compromised entire wineries with TCA contamination, no connection with cork.  This is another of the frontiers to be approached.  

On the environmental front, one of Quercus’ objectives was ‘to ensure the viability of cork forestations in Europe’. Ten years on, the WWF (World Wide Fund for Nature) report has emerged to refocus attention on the environmental aspects of cork oak landscapes. And fortunately for the cork industry, WWF are addressing the wine industry, challenging it to use more natural cork stoppers for the sake of the environment.  A more relevant approach towards sustainable cork oak landscapes may be accreditation by the Forest Stewardship Council. Certification means cork growers can supply to manufacturers traceable cork planks from forests certified to adopt landscape-sustainable practices. Part of this sustainability includes forest regeneration to prevent the landscapes from eroding.

But big plantations to increase the potential for cork stopper production are well underway. APCOR’S chairman said: “in the last ten years Spain and Portugal have planted nearly 150,000 hectares of cork forest … [so] I’m predicting we will have 15-18% more cork in 10 to 12 years from now.”  These are big plans indeed for an industry that some would write off. It’s true that the cork industry has lost market share, but an estimated 95% share of, say, a 12-14 billion stopper market in the early 1980s, to an 80% share of, say, an 18 bn stopper market today, is still somewhere between 10% and 25% growth in absolute volume terms. With a 27-year lead time for any increase in cork raw material, suddenly these plantations seem like a good idea.

That Quercus brought together eight groups from six countries (France, Germany, Italy, Portugal, Spain, UK) in a multi-discipline team should not be underestimated. It apparently took many meetings even before a title could be decided upon for the project. But since Quercus and the ensuing code of practice, the cork industry has dramatically changed the way it does things.  As APCOR’s chairman, Antonio Amorim believes the seminal moments of the last decade to be: “the change in the cork industry’s attitude towards quality and quality-related investments; the verticalisation of  the cork sectors’ leading companies, and the industry-wide adoption of GC-SPME technology.” (gas chromatography – solid phase micro-extraction).

Despite what has been achieved so far, there is still plenty more to do. Amorim said “the cork industry must avoid complacency and look for a total eradication of TCA.” The expanding boundaries of science and technology may provide help. For the moment, Hall said: “What matters is: does the industry and the consumer acknowledge that there is an improvement?”

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