Oxygen gets into closed bottles

Published by Sally on May 30, 2009

A version of this article first appeard in Harpers Wine and Spirit, November 2008, updated May 2009.

Oxygen ingress has become the new black for the closures industries.  TCA (the  mouldy, musty taint in wine) is last season’s outfit, and environmental considerations remain an underground movement, threatening to move into mainstream fashion at any moment. 

In its efforts to forge an environmental path, cork closure champion Amorim held a seminar on the sustainable future of natural cork, presented by Dr Miguel Cabral, their research and development director. According to communications director Carlos de Jesus, the seminar covered “anything that people want to talk about – carbon footprints, the latest research and development, TCA, new products, new oxygen permeability research.”

But cool chic is all about oxygen management, and OTR (oxygen transmission rate – how much oxygen passes through/past the closure into the wine) is the new three-letter acronym of closure cool.  It’s during the last year or two that oxygen ingress through/past the closure has quietly become the accepted norm.  Screwcaps are no longer considered hermetic by the mainstream, though it is difficult to pinpoint the origin of this, as the Stelvin brand of screwcaps have been available with two differently permeable liners for more than 30 years, and, according to Bruno de Saizieu, sales and marketing director of Stelvin makers Alcan Packaging Capsules, have been marketed as such.  

Why is OTR so ‘of the moment’? Managing oxygen is related to the mechanical and physical properties of the closure in contact with the bottle bore or top of the neck. Closures need to be consistent, and, by and large, it is the industrially made closures, where each and every one is the same as the others in a batch, that are likely to perform most consistently. With such consistency of closure, and therefore, it is thought, of OTR, trials and observations can be made from which wine behaviour in bottle can be predicted with confidence.  Dean Banister, the sales director for Oeneo, who make Diam, said: “at Oeneo we’ve been talking about OTR for a few years now and for us it is the next big issue for closures. For me the subject is being led by Oeneo and Nomacorc because we can both actually control OTR with our closures whereas it is not possible with natural punched cork.”

Indeed, earlier this year, synthetic stopper supremo Nomacorc, with G3 Enterprises and Lallemand, founded O2inWines, a group bringing together industry technical leaders to expand science-based understanding of oxygen’s relationship with wine. Inter-Rhône has just become the fourth industrial member of this Association, alongside academic members such as AWRI, INRA, UC Davis and Geisenheim (institutions in Australia, France, USA and Germany respectively).

Nomacorc’s vice president, marketing and innovation Malcolm Thompson, said: “there’s quite a buzz associated with the whole oxygen management in winemaking. Some as a direct result of the conference, a lot of it as a result of work Nomacorc has done specifically”, which includes four initiatives with leading institutes across the world, researching the effect of oxygen on different grape varieties and bottling conditions.  He added “the research is step by step globalising, with four programmes at AWRI (the Australian Wine Research Institute), INRA (the Institut National de la Recherche Agronomique) the Geisenheim Research Centre and UC Davis. And we’re nearing a position to announce a fifth programme in south America.” 


As well as OTR research initiatives, a new model of Nomacorc closure – Classic+ – has just been released, after a three year development programme. It has an OTR about 30% lower than their Classic model and Thompson said: “the Classic+ driver is from performance to preservation. We’re capitalising on breakthrough technology when we developed Premium.”  Classic+ adds another 12 to 18 months shelf life compared to Classic.

Nomacorc may have five different models on the market, but competitor Neocork  have adopted a different paradigm, with just a single product. Mark Coleman, their director of global business development, said with: “a decade of commercial performance in the marketplace, we’ve been reluctant to start compromising a proven formula because when you start changing materials or densities on such a technically engineered product, there will be compromises.” He emphasised their single product met the age-ability needs of 85% of the wine market, that is, drunk within a couple of years of bottling.

But trials are under way, he said “to address market demands of both a lower cost cork and one more suitable for wines intended to age five-plus years with products whose densities, mechanical and sensory attributes mirror the proven performance of our current product.”  Expect some news in late 2009/early 2010.


A similar time frame is forecast for news on new screwcap liners. At least two types of liner are undergoing trials, one with an OTR between the two existing liners on the still wine market, Saranex (higher OTR), and SaranTin (lower OTR), and one with a higher OTR than Saranex. 

At one of the leading screwcap manufacturers, Guala Closures Group, different types of testing has involved different materials. Their marketing manager Anne Seznec said: “we’re working on a liner with a 100% hermetic closure because we need to achieve an hermetic seal first, before we decide the rate of OTR that we want to put in the liner.”

Alcan Packaging Capsules vie for global top dog slot with Guala Closures in the long skirt screwcap market. De Saizieu said “we are making some trials with customers on finished products. We’re testing regularly those liners to be sure that what we expect is right with the wine. But this takes time because of the ageing.”


While both synthetic and aluminium closures are industrially made and therefore batches are expected to be consistent, natural cork, being natural, is argued to have some variation.  Single piece natural cork is still the most widely used cork closure with Amorim alone making about 1 billion of them, but, being single piece natural corks, they’re naturally subject to individual variation, though the amount is widely, and often inaccurately, debated. A two to three-fold variation is oft-discussed among academics, and there is also an argument that the high level of cork compression inside the bottle neck bore eliminates much of any natural differences between individual corks.

It may be difficult to offer a precisely measured OTR parameter for natural whole-piece corks, but it should be possible on high quality technical corks, such as Oeneo’s Diam, even though we don’t yet understand what a specific OTR means in terms of wine development in bottle.  

Nonetheless, OTR becomes a relevant topic of conversation to further that understanding.  Since the launch of Diam in 2004, Banister has been doing his bit to move OTR up the agenda. In fact, he said “we have not produced natural punched cork for over two years and we ended supply of this product in most markets at the end of 2007.” He added, “We will be a single technology company in the next few years, focusing only on the Diam technology” which means their ‘Reference’ product will be gradually phased out.


With Diam, Oeneo offer four levels of OTR, which, Banister said “because of the low understanding of the effect of OTR on wine we offer them on the basis of wine ageing potential [shelf life].” There’s also a differential cost “because of the density of each closure and the size of the cork grains.”

Carlos de Jesus says Amorim’s technical granular cork Neutrocork is their fastest growing stopper, though it’s long way behind the volumes of twintop.  On the various merits of single piece versus technical cork, he said: “Cork offers different products for different price points for different wines. You wouldn’t cross a desert with a 2CV [car], you might want something better adapted. We’re creating different products for the market, which is becoming more segmented. No one else can cover so many price points, we can offer something for £1 bottle or £1,000 bottle. 

And he doesn’t think the single piece natural cork stopper will fall out of favour any time soon. Using Bordeaux growths as his example, he said “If natural cork stoppers did not give you predictability and consistency, natural cork would have gone long ago. There has to be some consistency, there is a common sensory thread running through [different bottles of the same] wine.” He has a point. High level blind tastings would be tricky without some consistency across the board.

Though our understanding of oxygen management is at a foetal stage, OTR  and the closure is only one aspect, albeit a crucial one, of many, involved in managing oxygen. Before bottling, management through the vinification process and at bottling are crucial.  And oxygen ingress rates are affected by environment throughout the supply chain, from point of bottling to the consumer shopping basket and beyond.   

The reality is that we don’t yet know which level of OTR is good for a particular country or grape variety, or vintage, or vinification method, or bottle age. As Banister said: “”Do we really understand OTR, in short no not yet. Much work is being done on this subject and we know it matters but as yet it has not been quantified, so many variables, wine styles, winemaking style, expected consumption date etc. And remember that oxidation to one person can be seen as nice development by another.”


2 Responses to “Oxygen gets into closed bottles”

  1. Dr. Eberhard Kunze Says:

    Dear Sally,
    having first time now come onto a Nomacorc closure (on a bottle, which I discarded the rest of because
    of poor taste) I tried to find out, what Nomacorc essentially is.
    But apparently nobody publishes any detail about the chemistry involved, and appart from having
    found out that it seems to be a kind of foamed polyethylene I am still totally in the dark.

    Considering that the amount of diffused oxygen has any chance to be smaller than the elution
    of any eventually enclosed by-product or additive to the synthetical cork material, I would be glad
    to read more about what the chemists in these plants actually do – if possible, from an indepentent
    With kind regards,

  2. Sally Says:

    Hello Eb, as far as I’m aware proprietary patents exist for all the different synthetic closures, which means disclosure of exact construction is unlikely. It’s usually talked about in non-specific terms: food grade materials used; approximate shelf life, and more recently, oxygen transmission rates, etc. I’m not sure I can help you much more on that one, I’m afraid. Sally

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