Varying wine closures
My closures; real cork, synthetic, screwcap, agglomerated cork

As you may have inferred from the previous segments of this series, I am a fan of wines sealed with cork.  At least I am now. I’ve come from a neutral place, but more on that later. The reasons I’ve become a cork supporter are more than the typical ones given:  the opening “pop,” it’s romantic, it’s traditional, etc.  The reasons I’m going to share with you have more to do with actual science and sustainability than the romantic notions.  In addition, I will share with you what I think is the one closure that is superior to everything. Almost even cork.

The week that I went through three screwcap sealed wines (two in one night!) that were flawed was an eye-opener.  The wines ranged from smelling like moldy paper to smelling like somewhat spoiled egg salad to smelling and tasting like nothing.  Understand that I had rarely run into problems with screwcap wines before. Why was this happening now? Aren’t screwcaps supposed to be the panacea to avoiding the incidents of flawed/corked wines?

Well, my research brain kicked in and beginning several months ago, I started reading all I could about flawed, corked, stinky, reductive, skunky, and otherwise damaged wines.  What I found surprised me, and I want to share what I discovered. Those of you who are old hands at this may find this report uneventful and no new news, but I found that “conventional wisdom” was doing damage where it wasn’t necessary and that the entire truth was either being hidden or ignored. I found that many people blogging or reporting online were satisfied with parroting the status quo. I call that lazy research and lazy reporting.

What is “Cork Taint”?

When I started this project, I did not know that it would become so extensive.  What this has done is to make me well versed in the subject of “cork taint” (consider those air quotes), and able to discuss it with fluency with any authority.

As an aside, I’m employed at the Day Job™ as an analyst. I am given problems to solve, and I have to use every tool at my disposal to solve them. For instance, last year I had to find a way to create a new Intranet site that would run concurrently with our existing Intranet. The old site would eventually be phased out and the new one would be released in a staggered process to all employees as their computers were upgraded with current operating software. My research included finding industry best practices, which included assessing the appropriate foundation software and framework, typical budget, time frames, and project staff requirements. In addition, I had to break down whether these costs would be acceptable with an outsourcing option or if the project would have to be completely done in-house. I had to communicate with our Information Technology department regarding systems compatibility and upper management regarding feasibility in making such drastic changes. Afterwards, I wrote an extensive report giving bibliographic information and other resources. In addition to the ability to research and write, I also have an IT background.

Since I knew what it would take in order to build the in-house system, I was tasked with creating the new site, which I did while working and consulting with the IT department. This required me to learn a completely new CMS (Content Management System) and new language (.asp) while being saddled with a deadline of four months. Understand that according to industry best practices, the typical deadline for such a project was six to nine months with a staff of four to six. There was just me!

So as you can see, I’m not a lightweight when it comes to getting at the bottom of a dilemma that has to be solved and resolved and making suitable recommendations when the situation calls for it.

One of the related items that caught my attention was the previously mentioned comment by Kermit Lynch regarding cork taint.  He indicated that cork taint has often been misdiagnosed; in other words, cork was blamed for something that had nothing whatever to do with cork.  How is that possible?

Wine Wonk Warning: Several paragraphs of scientific geek nerd stuff that made me wish I’d really been paying attention in chemistry follow.  Here ya go.

The primary source of cork taint is 2,4,6-trichloroanisole (TCA).  A secondary cause is 2,4,6-tribromoanisole (TBA), a close structural relative.  However, although common knowledge indicates that TCA taint in wine is caused by cork, it can be caused through cork or any other material that may absorb TCA or allow it to be fixed upon it, such as barrels and the cellars where the wine is made.

The definition of TCA/TBA as defined by the Practical Winery & Vineyard Journal, November/December 2008 is as follows:

Chemically, 2,4,6-TBA is a derivative of the anisole (or methoxybenzene) family of compounds, which contain at least one atom of a halogen (fluorine, chlorine, bromine, or iodine) and thus are termed haloanisoles. Haloanisoles are formed from halophenol compounds by microbes, such as filamentous fungi, via a process called biomethylation.

However, there’s more to it than just having this chemical infect the wine. While TCA is most often associated with wine taint, it and its close relative, TBA, have been responsible for taint in other industries as well.

An article in Pharm Tech entitled 2,4,6-Tribromoanisole and 2,4,6-Trichloroanisole: A review of taints and odors in the pharmaceutical and consumer healthcare industries (Sep 2, 2012, Parenteral Drug Association, PHARMACEUTICAL TECHNOLOGY, Volume 36, Issue 9, pp. 56-62)(see bibliography) discussed the incidents of TCA/TBA contamination in the pharmaceutical and consumer healthcare industries.

Because these materials are manufactured and sealed under much stricter oversight than wines, the fact that they became contaminated with these agents was a cause of great concern.  While these agents are considered to be largely harmless, they have apparently caused some gastrointestinal distress in susceptible individuals who ingested medications that were tainted. Because of the complaints, a task force was organized in 2010 to find the cause of the “cork taint” in these medications and why it was so widespread. Understand that in the last several years, there have been numerous recalls of medications that have suffered from cork taint.  Information about some of these recalls will be listed in the bibliography at the end of this series.

The primary cause turned out to be wooden pallets that were sourced from South America and were routed through Puerto Rico before ultimately arriving in the United States and other destinations.  These pallets had been treated with a specific wood preservative which, for all intents and purposes, acted as a “food” for TCA/TBA. The substance 2,4,6 tribromophenol (TBP) which is used in some countries as a fungicide, is the source of the taint problem. The conversion is caused when certain specific fungi come into contact with TBA which, once it is airborne, can attach itself to any surface. It has a special affinity to plastic.

But it gets worse.

Johnson and Johnson began the actual search for the problem of pharmacological contamination in their products. One of the worse was the contamination of a drug with the trademarked name of PREZISTA®, a medication used for AIDS patients whose immune systems are already highly compromised.  The contamination was limited to the UK and only in one specific size of the medication, but the implications are pretty clear. This problem could have the potential of causing a lot of damage, not only to J&J (their Janssen division), but obviously to the compromised patients as well.

There were several such recalls, and all were linked to the affected pallets.  The problem is that there are about 1-2 billion such pallets in the US alone, so recalling all of them is difficult if not impossible.

According to the FDA, this is not a new phenomenon.  In a paper entitled  Questions and Answers on Current Good Manufacturing Practices, Good Guidance Practices, Level 2 Guidance – Buildings and Facilities, the question of contamination was addressed.  One of the questions and answers really caught my attention:

Why is FDA concerned about drug contamination with halogenated anisole compounds, such as 2,4,6-tribromoanisole (TBA)?

Reports, including some dating back several decades, describe a moldy or musty odor in food (and wine) products due to contamination with trace amounts of halogenated anisole compounds such as 2,4,6-tribromoanisole (TBA).   An odor attributable to the presence of a halogenated anisole compound can be detected by consumers even when the offending compound is present at parts per billion or lesser levels.  Recently, an upward trend in consumer complaints about musty or moldy odor led a drug firm to identify TBA as the odor-causing compound.  The firm’s investigation of this incident led to the detection of TBA in several oral products.  The firm traced all of the contamination back to the use of certain wooden pallets used to transport drug packaging materials.  TBA is prone to volatilize and adsorb onto articles stored near the TBA source.  Because of their volatility, it appears that even minute levels of halogenated anisole compounds can adversely affect a large quantity of product in a single contamination incident. (emphasis mine)

I found an earlier Swiss study that indicated that mustiness in screwcap-sealed wine bottles was almost always TCA.  The permeable plastic lining was thought to be the problem with this contamination.  In addition, the study pointed out that any mustiness in the bottles sealed with cork was attributed to TBA (see above FDA comment), and none was contaminated with TCA.

The Closures


Glass closures and real cork

I wanted to get these out of the way quickly.  This is the only closure that is superior to almost everything, at least as far as straightforward sealing of a bottle is concerned.  They are made of glass with a thin gasket of silicone to seal the bottle securely.  The silicone does not come into contact with the wine. There is a small amount of breathing that takes place with such closures, and they are completely inert.  While they may still have some of the problems that are found in screwcap-closed wines, they are relatively fewer in number.

The reason you don’t see glass closures more often is because they are expensive.  Depending upon the source of information, you can make about 10 to 100 synthetic closures for the price of one glass stopper. In addition, outside of Europe there is no machinery to seal the bottles and they all have to be done by hand. They are absolutely beautiful, however. They make the coveted “pop” when they are being removed from the bottle (scoring very high on the romantic wine night scale), and they make for easy resealing of open bottles. They are pretty much close to perfect, and I wish I could find more affordable wines that are thusly sealed.

Synthetic Corks

Synthetic Corks are closures made to imitate natural cork but are made out of plastic.  You’ve already seen my issues with plastic in the previous segment of this series.  I recently watched a video showing how synthetic corks are made, and it stated that the process started with “little plastic beads.”  Of course, that’s not entirely true.  It starts with petrochemicals, which are refined into little plastic beads.

Fortunately, synthetic corks are not used on “good” wines, but on wines that are meant to be drunk almost as soon as they are purchased. That keeps the risk of petrochemical exposure and tainting of wine down to a minimal level, and it keeps the cost of a cheap bottle of wine, well, cheap. With the questions and ongoing research of the causes and effects of endocrine disrupters – to which some categories of plastic are significant contributors – I really don’t want my wines touching the synthetics.

The manufacturers of synthetic corks are quick to point out that there’s no cork taint when wines are sealed with plastic. My answer? That assumes that cork taint is caused by cork.


See report on synthetic corks above. Fortunately, there doesn’t seem to be a lot of these around. I’m guessing that there’s poor customer acceptance. They are ugly. Just my opinion.


These are the panacea, they told us.  If you seal your wines under screwcap, you don’t have to worry about having cork taint, they said.  This was repeated everywhere, has become conventional wisdom, and is generally accepted without question. It was something that I more or less believed until I saw a few comments that made me stop and actually think.

I will agree that there appears to be fewer incidents of cork taint in screwcapped wines.  As noted in the studies above, however, that doesn’t mean that it doesn’t exist, simply because of the nature of the contamination.  If cork taint doesn’t come from cork – which I realize is a rather contrarian viewpoint – then it must come from another source, which I have already covered.

Screwcaps are easy to open and most pop and pour wines or casual wines are terrific when sealed in this manner.  A significant number of my bottles are thusly sealed, somewhere in the range of about 20%.  I believe that is close to the acceptance of screwcaps, so I’m right there in the norm.  I don’t have an aversion to screwcapped wines, just to the propaganda surrounding them.

As mentioned before, wines under screwcap can have their own issues, which I’ve been unfortunate enough to encounter.  And yes, I’ve experienced corked wines as well; that musty smell is just unforgettable.

However, there are some pretty serious flaws that can happen under screwcap which can render wines just as undrinkable as a corked wine.

I felt that all of this had to be reported because as wine people, we tend to have a narrow focus when it comes to our wines.  The fact that these compounds are not only not unique to the wine industry, but they are problematic in all areas of food and beverage. In addition, these agents are a dangerously significant issue in the pharmaceutical and healthcare industries, and this is important to understand before any kind of quality discussion about “cork taint” can be started. We can’t have blinders on although it may make us feel like we’re the only ones with the issues. We’re not.

What I wanted to show you was that cork taint ain’t always “cork taint.”

Coming Next: Aye Aye Mercaptan!


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