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Nomacorc research

Does the threat of cork taint raise the possibility that wine corks are goners? The research continues with interesting results about consumers' sensory observations of aroma, taste, and mouthfeel.

America (Country Appellation)

Getting Closure
The continuing search for the best way to seal the bottle

by Eleanor & Ray Heald
January 18, 2008

Have you noticed that more people today are using the word closure? Everybody, it seems, wants closure to something. In the wine industry, closure is a pet word, but with a different meaning. Two APPELLATION AMERICA postings, Are screw cap wine bottles sensible or not? and To cork or not to cork? elicited a number of thoughtful comments from readers. One, in particular, from George Vare, proprietor of Napa Valley’s Vare Vineyards, inspired us to follow up on the topic. Perhaps the most pressing concern about finding the perfect closure is the problem with cork taint or TCA. Let George Vare explain:

DropCap quote DropCap A48 worse issue with TCA [the chief cause of cork taint is the presence of 2,4,6-trichloroanisole or TCA] is that the compound may exist in a wine at a subliminal level, such that the fruit character of the wine is killed, resulting in a 'dull' wine that has no redeeming graces," Vare notes. "In this case, the consumer does not recognize the 'corked' issue but instead blames the producer. Enter Vare Vineyards. As a brand new winery offering a variety of wines [such as] Ribolla Gialla - that few people have heard of, let alone tried - we cannot afford the exposure to TCA in a subliminal situation."

Vare explained that he wants consumers to enjoy this new varietal wine and not be put off by a matter beyond his control. He took charge by choosing to use a synthetic closure made by Nomacorc. "In truth," he continued, "we could have used a screw cap, but the glass companies have been slow to produce a variety of glass-accepting screw caps, especially in the 500ml size which we use."

Now, there's an issue not brought to light in the earlier postings. Vare suggests that the Nomacorc closures have worked well and he's had no consumer or wine trade kickback. If you've read the earlier APPELLATION AMERICA postings on the topic of wine bottle closures, you also know that winemakers have remarked that screw cap closures do not allow oxygen to reach red wines as they age.

Thus, the question begs: what research has Nomacorc done to lead them to offer a satisfactory closure?

Project Broomstick

corkAfter opening several wines ruined by cork taint in 1993, Belgian businessman and wine aficionado Gert Noël and his son Marc started Project Broomstick, in order to create a closure based on foam extrusion technology. After six years in R&D, they introduced the first Nomacorc closure.

Using the company’s patented co-extrusion manufacturing process, each closure consists of a foamed inner core layer and a flexible outer skin. This method creates uniform closures that yield consistent oxygen (O2) transfer rates. Nomacorc closures look and feel like natural cork and address the problems of cork taint, breakage, crumbling and inconsistent wine preservation.

Nomacorc’s research study was conducted world wide to ensure fair and optimum results.
As a result of Nomacorc's post-bottling chemistry research, its product line has been expanded to include a portfolio of wine closures, each one designed for different winemaking styles, oxygen management requirements and shelf-life prospects.

In May 2007, during a company-hosted interactive seminar at the London International Wine & Spirits Fair, Nomacorc released results of its post-bottling chemistry research illustrating how closures affect wine development. The study [Click here to read how the research was conducted.] relates to O2 impact on aroma, taste and mouthfeel and allows winemakers to better judge optimum oxygen transfer rates (OTR) for closures and the impact of O2 on bottled wine evolution.

Sensory panelists rated aroma, taste, and mouthfeel perceptions. From this, researchers concluded that each closure type (low, medium or high OTR) led to differences in wine development.

Sauvignon Blanc, with a low OTR closure, had the highest degree of fruit preservation but this was accompanied by the presence of reduced characteristics. The bottle with higher OTR was less fruity but free of reduced character defect. Shiraz with a low OTR closure had both bitter and astringent characteristics. The medium OTR closure was the best balanced and least bitter and also had rounder tannins. The wine with the high OTR was found to have more bitterness yet had the lowest astringency.

Controlling Wine Development

corkWinemakers can now use these research results to effectively control wine development in the bottle. No, no, we didn't say ‘manipulate’. The operative word is ’control‘ for positive development and the best showcasing of appellation-identifiable characteristics. These are not wine's dirty little secrets as they have been referenced in some consumer-oriented articles. The closure initiative, which is ongoing in today's wine industry can only lead to better wine experiences for consumers now and in the future.

Aroma descriptors can be traced to specific molecules, which, when identified, can be further linked to their O2 sensitivity and thus it can be determined which closure OTR optimizes desired wine development. Because some aromas are oxygen sensitive and others are not, Nomacorc created a classification system, which groups various aroma classes in relation to their O2 sensitivity, such as (common descriptors in parentheses):
--Mercaptans (passion fruit, grapefruit, gooseberries, cat pee, burned rubber, or even rotten eggs).
--Terpenes (citrus, lime, geranium, lychee, rose, pine or coconut).
--Norisoprenoids (flowery, tobacco, violet, petrol or earthy).
--Esters (candy, tropical fruit, peach, banana or melon).
--Higher alcohols (herbaceous, cranberry, mushroom, vegetal, or malt).
--Volatile Phenols (horse, band-aid, smoky, vanilla, oak or bread).
--Pyrazines (bell pepper, grassy, chocolate, roasted nuts, potato and earthy).
--Anisoles (cardboard, corked and musty).

Using this classification system, Sauvignon Blanc aromas are in the O2-sensitive category (mercaptans) and thus benefit from low O2 exposure. Sauvignon Blanc's reduced characters (volatile sulfur compounds) are found under anaerobic conditions and contact with O2 lowers
The wine industry as a whole has not yet arrived at perfect closure but what seems evident is that there will no longer be a single closure.
the concentration. Thus, a winemaking style influences closure choice. For a reductive winemaking style, which maximizes fruity notes, yet at the risk of producing reductive characters, a winemaker can use a closure with higher OTR to lower the risk of reduced notes while still preserving a wine's fruity character.

In the Shiraz experiment, O2 influences the taste and mouthfeel sensations of bitterness and astringency. Bitterness is associated with smaller tannin molecules (monomers and oligomers) in a wine. Astringency is linked to longer-chain molecules (polymers). Tannin molecules are reactive and constantly changing in size, often breaking into smaller molecular structures or inter-reacting to form longer molecules.

This depolymerize-repolymerize tannin tendency leads to a broad range of molecules of differing sizes, all of which influence a wine’s perceived bitterness and astringency. Mediated by acetaldehyde (detected as ripe fruit aromas) in a wine, tannins can undergo cros

READER FEEDBACK: To post your comments on this story, click here

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Reader Feedback

Reader Comments... [10]

Nathan R. Carlson , Winemaker
Tolosa Estate / Courtside, San Luis Obispo, CA
Um... this seems to border on cheerleading for Nomacorc. I don't see any discussion of the main criticism of this closure; that it lets TOO much O2 in? I have a really well controlled, production scale closure trial which includes Nomacorc as one treatment, it has been running for nearly 2 years, and is showing some really clear differences between the closures. I'd be delighted to make the results to date available to you, and can even send samples from the trial if you'd like to do sensory on them? Just drop me a line or email.

Steve Edmunds , winemaker
Edmunds St. John, Berkeley, CA
This article is interesting, but in a pretty limited way. Why isn't there any information about other kinds of closures, and other manufacturers?

Patrick Llerena , Winemaker
Iridesse Wines, Healdsburg, CA
My primary concern regards the actual Nomacorc product. What is the product made of at base levels? At there levels of thalates that might be of concern? Is it a petroleum by-product? Can it be manufactured from any post-consumer materials?

Chris Hawes , Owner
Bear River Vineyards, Nova Scotia, Canada
APPELLATION AMERICA forced me to loose my willingness to concentrate on the facts relating to wine bottle closures with this article. First off, the illustration at the beginning is an atrocious grade three cork. Talk about exposure at a subliminal level! To further bend my head on this topic could be futile, considering the weight of influence chucked behind the seemingly sponsored opinions of this little pyrite nugget. Cork you I would!
~ Chris Hawes, Bear River Vineyards

Andrew Schweiger , Winemaker
Schweiger Vineyards, St Helena, CA
This is another tragic example of the poor research that APPELLATION AMERICA has been putting into its articles. Rarely do their articles cite more than one source, but often their reporting is completely un-truthful (paragraph four, 'screw cap closures do not allow oxygen to reach red wines as they age'). With this kind of reporting, I'm curious if their next article will be titled, "Why it rains... God is sad and is crying".

Merry O'Callahan , V.P.
Wyldewood Cellars, Kansas
I came to read the article because I was interested in closures being used. Did not expect a "commercial" type ad for Nomacorc. Waste of time. We do not use corks, and we have won hundreds of awards with our wines. From our customer comments -- People are very tired of trying to get a cork out of a bottle; having to carry a cork remover to enjoy a bottle of wine away from home. Reclosing the bottle is easier and more efficient, particularly for senior citizens who enjoy wine but hate fighting the corks. People USED to ride a horse to work, or drive a wagon. Why keep using such an out-moded way of closing a bottle of wine?

Roger Dial , Publisher
Appellation America, Napa, CA
As the Publisher of APPELLATION AMERICA, I am always pleased to see reader feedback... and even "blow-back", when it is deserved. However, I'm seeing in these responses above charges of one-sided partisanship (for Nomacorc and/or for the anti-cork message). Nomacorc is not a sponsor of Appellation America, and the Healds’ delving into Nomacorc's timely research is simply one more piece in their on-going and open-minded series on the cork issue. Perhaps the shoot from the hip, one-read critics would do well to read the other two installments, cited at the top and bottom of the current piece.
~ Roger Dial

Robert Morey , Director of Sales
It would have been nice to discuss other closures such as ZORK, particularly ones that have a proven track record and for which numerous studies and trials have been released... Feel free to call or email if you would like to learn more about ZORK, or go to our website.

Olav Aagaard , Director of Global Resear
Nomacorc, Thimister-Clermont, Belgium
In my view, this article is not about the pros and cons of a specific closure system. It writes about Nomacorc’s research on finding the right amount of oxygen going into the bottle in order to allow the wine to develop as the winemaker intended. This article describes one of the first results we presented during the LIWSF show in May 2007. During that presentation we tasted bottles of the same vintage wine which were aged under different closure systems (screw cap, natural cork, technical and synthetics closures). The results of the tasting were correlated to the amount of oxygen which went into the bottle via the closure (referenced as high, medium or low OTR) and explanations for the noted differences in tasting were given from a chemistry point of view. Nomacorc aims to understand how oxygen is changing the wine during aging so that we can optimize the OTR of our closures to match the desired outcome of the wine preservation. The research has just begun and is aimed to continue to 2011. We are committed to share our results with you so that hopefully everybody gets convinced that it is not about personal closure preference but about the right closure for your wine.

Richard Grant Peterson, , PhD , winemaker
Richard Grant Wines, Napa, CA
I'm bothered by all the simplistic and repetitive parroting of the Absolute B.S. that says "Closures are supposed to 'breathe' at some rate or other to control the rate of wine aging precisely" - as if we know exactly when each bottle of wine will be opened and can time our "aging" to match the consumer's whim.

We did that lab work more than four decades ago and I say again for the thousandth time:
Sound corks DO NOT transmit oxygen! Neither is oxygen transmission through closures what we want! Wine aging and the development of 'bottle bouquet' during bottle age is anaerobic. The effect of continued aeration is something quite different, and it takes place in steps:
(1) it oxidizes and removes the SO2 protection from the wine, then
(2) it oxidizes and removes the tannin, pigment and other polyphenolic protections from the wine and finally,
(3) it oxidizes and destroys the flavor of the wine, followed closely by browning, polymerization of the oxidized pigment and other polyphenols, etc. This completes the oxidative destruction of what would have been a perfectly preserved bottle of fine wine if the closure hadn't leaked.

Why on earth would anyone in his right mind want to deliberately aerate, and oxidize otherwise fine table wine?

At the risk of modifying the subject, I'll take the time to answer one of the most prevalent questions I hear from the wine drinking public. There is a great deal of confusion about the 'good aeration' of decanting before drinking an old bottle of wine -- and the 'bad aeration' that leads to oxidation. Most people don't understand either one of them, but neither is very difficult.

You have to understand the difference between aeration and oxidation:
When you aerate an old wine, you mix air into it and make it easy to drink and enjoy. But that air doesn't oxidize the wine until it has had time to do so. The oxidation of wine by dissolved oxygen takes place slowly and you won't see the effect for several hours, maybe overnight. Once a wine has become oxidized, it is dead and cannot be revived.

One of the enduring chemical truths I learned from the master, Professor Maynard A. Joslyn, in grad school wine research was that "Wine becomes reducing in closed containers, and it naturally lives in a reducing atmosphere in sealed barrels, tanks or bottles." That is extremely important to know if you want to understand bottle aging. I've opened many bottles of 30+ year old Cabernet and, nearly always, those wines have a 'reducing funk' at the time they are first opened. There is no H2S -- they aren't "reduced," but only living in a mildly reducing atmosphere. All they need is to be decanted to remove solids, if present, and then poured with splashing back into the (rinsed) original bottle. Then allow the wine to stand in its now aerated state for another few minutes before serving. The reducing funk disappears for good reason: everything we eat or drink is bathed in air as it passes over our taste (& nose) receptors. We are used to whatever the taste of air in food and drink is. We like it. But old wine that has been sealed up inside a bottle for thirty years lives in a reducing atmosphere -- that is the chemical opposite of aeration. All we have to do to bring out the goodness of its aroma and bouquet is aerate a little to re-establish the aerated surroundings we want to taste it in and, presto, decanting did the trick.

I tell you this so that even non-chemists will understand the truth that wine aging never takes place under oxygenated conditions. It's because those are the conditions that lead to oxidation and destruction of the good things in wine. In a perfectly sealed bottle, the wine will not oxidize but will develop bottle bouquet - which it cannot do if that #%K&@! damned destructive oxygen is present.

Okay, you can define "wine aging" as 'slowly oxidizing it until the wine isn't drinkable any more' if you want to. That's what those idiots do when they promote deliberate oxidation of your wine through selectively defective closures, although I'll be kind and say that they don't do it on purpose -- it's just that lack chemical common sense.
~ Richard Grant Peterson

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