Home Events Advances in Cork Quality: An IQ Session

Advances in Cork Quality: An IQ Session


The Innovation & Quality Conference 

Cyril Penn opening IQ

The annual IQ (Innovation & Quality) Conference happened in St Helena last week bringing together wineries from all over the Western United States with suppliers of cork, barrels, screw caps, and other materials needed in making wine. Central to the conference is a trials tasting tent in which vintners from the West coast United States share winemaking trials – the results, the insights gained, any pertinent data, and the wines themselves to taste. Trials range from side-by-side experiments on cellar techniques such as differing lengths of extended maceration alongside straight to press wines from the same fruit, or extended aging in different types of vessels, to vineyard trials such as side-by-side clonal tastings on Pinot noir, or side-by-side tastings of the same clone grown in different soil types. If you time it right, you can spend the whole day just attending a series of trial tastings of this sort.

In addition to the trials tent there are also a series of discussion sessions, some with wine to illustrate, some without. The sessions are great because as hard core wine-geek-fest as the tasting trials are, hearing the most current innovations in wine technology or knowledge from the world’s top experts on whatever the particular matter is just does not get old. I got to attend both a session on the most current advances in cork quality as well as a session on tracking phenolic make up in Cabernet Sauvignon from the vineyard into the winery and through to bottling. It was awesome.

Advances in Cork Quality

Miguel Cabral of Amorim Cork

The Cork Quality session was rather mind blowing. In the last two years two cork suppliers – Amorim Cork and Cork Supply USA – have developed technology that has made it possible for them to release natural cork guaranteed to be TCA free. The implications of that advancement alone are mind boggling for the global wine industry. The technology is equally impressive.

Miguel Cabral of Amorim Cork came from Portugal to present to attendees about their ND Tech system. Corks guaranteed to be TCA free thanks to ND Tech are now available in the United States. Producers of premium wines in the United States have begun bottling wines with the guaranteed corks. From what I heard wines from both the 2014 and 2015 vintages have been bottled using the ND Tech corks depending on the vintner’s aging regime prior to bottling. Three producers – Jennifer Williams of Arrow & Branch, Jennifer Rue of Invisible Hand Winemaking, and Andy Erickson of Favia Wines – each have bottled some wines with the ND Tech guaranteed corks. The session included a winemaker panel of these three producers giving their thoughts briefly on the advantages of natural cork over other closure types, while David Ramey of Ramey Wines also spoke in favor of DIAM. Some of his thoughts are included here in the final section on Implications of the new guaranteed corks.

Greg Hirson of Cork Supply USA shared information about their DS100+ system, which is also able to produce corks guaranteed to be free of TCA.

TCA Studies

Peter Weber of the Cork Quality Council spoke briefly about advances in cork quality, sharing our current knowledge of TCA in preparation for us to then hear the most current innovations as seen in ND Tech and DS100+.

As Peter explained, TCA in cork is one of the issues in the wine industry that we know the most about thanks largely to on going research done by ETS. The original, groundbreaking study on TCA was done 18 years ago. Results from that original study transformed how we dealt with cork and led to massive reductions in instances of TCA in wine.

Prior to that 18-year old study, understanding of TCA testing was a simple binary system. Cork was recognized as either good or bad but most testing was done prior to the cork getting wet. Such tests were based entirely on human nose detection so recognition of the chemical was extremely limited and unreliable. An entirely new method of testing TCA was developed as a result of the 18-year old study that led to a huge leap in accuracy. Additionally, we learned more insight on the relationship between cork and wine, better realizing how TCA was released into wine specifically because it had gotten wet – that is, it is not enough to check a dry cork as TCA is released over time from the cork becoming wet – which transformed our understanding of quality control in the bottling and storage process as well.

Since 2001 new quality control programs on cork production and use have been in place leading to TCA levels today being 96% lower than they were in 2001. (Again, mind blowing.)

Peter clarified too that in studies on cork quality TCA is understood as a specific chemical contaminant in cork. In a general wine context many wine professionals refer to cork taint in general as TCA, when in actuality there are other forms of cork taint besides TCA. Other types of cork taint more generally depend on cork cleanliness rather than the specific chemical presence of TCA. High quality cork producers, then, implement cork steaming procedures that can remove other forms of cork taint while preserving the cork’s structural integrity. TCA cannot be removed in this way, however, and instead TCA infected corks must simply be discarded from use in wine and instead used for other purposes such as cork tile or board.

ND Tech

Miguel Cabral of Amorim presented their ND Tech system, which has already begun supplying guaranteed corks to the United States wine market. As Miguel clarified, most recent work on improving cork quality has revolved around eliminating TCA. For vintners, TCA serves as ground zero in storage issues. The goal is to eliminate it in cork so that more sophisticated aspects of cork quality can be studied instead. Both Miguel and Greg Hirson of Cork Supply USA, for example, agreed that now that they have successfully created technology to eliminate concerns of TCA in cork research, resources can now be directed to our better understanding oxygen transfer rates of cork in order to also better understand wine aging.

The ND Tech system has been developed over several years using equipment that tests each individual cork for TCA. Today, ND Tech equipment is able to verifiably guarantee that TCA levels in any particular cork are below 0.5 nanograms per liter. Human ability to detect TCA has a threshold of 2 nanograms per liter. So, ND Tech effectively guarantees any screened corks will have no detectable TCA.

To guarantee the ND Tech system’s effectiveness Amorim created several internal cross-checking procedures but they also had the system sent internationally so it could be verified by third-party studies. Both the Australian Wine Institute and Hochschule Geisenheim University found the system to be 100% effective.

Currently, in 2017, ND Tech is able to screen 42 million corks per year. That number will continue to increase as the testing rate is dependent only on the number of ND Tech screening machines they have in place.


Greg Hirson, the Director of Tech Services for Cork Supply USA, shared the technology behind their DS100+ system, which also tests corks to guarantee they will be TCA free. The DS100+ technology is utterly distinct from that of ND Tech but both have the same final result of guaranteed corks with TCA levels below 0.5 nanograms per liter.

The DS100+ technology was finalized slightly later than ND Tech and so currently Cork Supply USA is able to verify 20 million corks per year. Again, that number will increase as it depends only on the number of machines they have in place.

Greg did a great job at helping to make sense of what it means to say that any single cork will have less than 0.5 nanograms per liter. He walked us through extensive calculations to ultimately show that 0.5 nanograms per liter of TCA in any one cork is actually equivalent to being able to guarantee there will be not even a single fruit fly in a 40 acre vineyard. Did you catch that? NOT EVEN A SINGLE FRUIT FLY IN A 40 ACRE VINEYARD. (AGAIN, MIND BLOWING.) Even more impressively though, it is also equivalent to being able to screen for and eliminate that metaphorical fruit fly in less than 20 seconds, as the DS100+ technology works that quickly.


While screw cap made huge improvements in the world of wine in terms of radically reducing TCA, and certainly in eliminating TCA caused by closure, screw cap closures also have their own issues including bottle reduction and changes in aging from lack of oxygen exchange. It isn’t always ideal for a wine to barely evolve for years in bottle. Various adjustments in screw cap technology have been made to address these issues.

Synthetic or conglomerate corks are also a reasonable option in many cases. Since the focus of the session was on guaranteed natural corks there was not extensive consideration of synthetic corks. However, the winemaker panel did include some consideration of DIAM corks. David Ramey explained that he has done his own winery trials considering screw caps, vino lock glass closures, a range of synthetic cork types, various natural corks and DIAM. Today he uses all DIAM type closures across his wines, adjusting the DIAM quality level to quality needs for wine type. As he explained, in his view, OTR, or oxygen exchange rate, is the most important part of cork (or closure) quality as it allows proper aging of wines. When a bad cork prevents a wine from reaching its full aging potential we tend to treat it as if the wine has gone bad, when in reality it is that the wine had a bad closure. The inconsistent density and structure of natural cork works against standardizing expectations for such a closure. DIAM, on the other hand, is made to deliver expected levels of structural integrity and so OTR can be better expected as well. While David admits DIAM may not be the only solution he turns to in the long run, currently he has found it to be the best option.

For those reliant on natural corks, it isn’t clear that every wine needs a cork guaranteed to be free of TCA. Different wine types and different wine markets have very different needs. It might make more sense for wines bottled to drink the same year they are released to be bottled under screw cap, for example. Or, it might simply make sense for less expensive wines to be bottled under standard cork. The risk of small portions of TCA might be economically reasonable on less expensive wine.

Guaranteed TCA free cork does, however, make a lot of sense for premium wines expected to sell at higher prices. Public perception still prefers cork for fine wines, for example. Additionally, premium wines tend to be made from more structural varieties such as Cabernet Sauvignon or Nebbiolo that benefit from oxygen exchange in bottle loosely speaking. Additional cost (which, unfortunately, I don’t have the details on for these corks) can be more readily absorbed in premium wines and there is also far more to lose from a bad cork on expensive wines even if it is a relatively low percentage of TCA. Additionally, such producers gain the advantage of eliminating the cost of back up bottles when sending samples to distributors or writers.

Post update: the article has been edited to add additional comments on reasons to consider DIAM cork. 

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  1. Thank you for the great summary on this session! To add a point of clarification – NDTECH is a technology developed by the Amorim Group. In the United States market 2 companies offer cork which have gone through NDTECH – Amorim Cork America and Portocork. Jennifer Williams along with Andy Erickson both purchase ICON Certified cork from Portocork which Utilize the NDTech system to Guarantee each cork.

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