The Final Word on Bottle Enclosures (…yeah, right!)

It really boiled down to these two enclosures…

A few Wednesdays ago on #ONWineChat, we had a lively debate on the “best” bottle closure. Although titled “Screw caps, corks, or Synthetics – what’s best?”, we expanded the conversation to include any type of bottle closure – crown caps, glass closures, and composite corks were all discussed.

While we did see lots of agreement with point made by Michele Bosc of Chateau Des Charmes (@MBosc): “no such thing as a perfect wine closure IMHO”, we did manage to hear opinions and facts representing many different views. Below I’ll detail some of the different closures discussed, and what people had to say for and against each.

Is the Cork Romance Over?

Many would agree that much of the tradition and associated romance lies with cork closures…

@ElizabethG45: doesn’t matter to me (now) although I like Old School? & will choose over other when I want 2 impress!!

@allieoppenlaender: To me, wine is history, art, a story, a new memory to be made, therefore, I’m a traditionalist that wants cork

About this time, the topic turned to “breathing” and the benefit cork has over other enclosures:

Do Corks Breathe?

@CREWinery: Synthetic corks and aluminum caps do not breath & my wine can not age with out oxygen. I like corks

Which prompted this response from Ed Madronich of Flat Rock Cellars and the back and forth with Michele and Ed:

@UnfilteredEd: Breathing corks -one of the great myths of wine. If they do let oxygen in the result is random oxidation. science to prove.

@MBosc countered: Cork is permeable cellulose matrix. O2 exchange happens. Has been proven

@UnfilteredEd then countered with a very logical point: Then why are not all sparkling flat? pressure would force the CO2 from bottle if breathed

So I went in search of articles about cork “breathing”. I figured there must be scientific studies out there that would prove Ed’s point or Michele’s point (admittedly as someone with a technical background, Ed had me on why sparkling wine doesn’t go flat if cork “breathes”).

“Please Stop Telling People Corks Breathe”

“Corks Do Not Breathe – Part 2”

(I think they let you read a couple articles a month without subscribing…or they did when I read them). The articles clearly concluded that corks do not breathe. If you read all of the comments (as I did), you see that some challenge the methods used in the test, etc. The one question I was left with (although I did conclude that corks do not breathe), is that occasionally corks leak due to an imperfect seal with the bottle, and my thoughts were that this may be due to large temperature variations. And if they can leak fluid out, then arguably they can let air in.

Cork Failure Rates

So while cork does have the romance aspect nailed, there are still issues. What other industry would accept the high failure rates that cork has?

@FortBerens: Still can’t find a product with a fault rate of 3-5% to succeed in long run. Ipad? Coca-cola? BMW? Fail rate of cork is too high.

@UnfilteredEd: What industry accepts the failure rate that wine does with cork?

@littlemissmocha: Okay, flat out, I love the traditional feel of cork. But someone do the math on bottles sold in ON, or Canada x 5% or 2% corked (I quickly calculated that 2% is 4.4 Million bottles a year in Canada, using recent Canadian wine production numbers of 220 million bottles).

Jen Taylor added this point – @littlemissmocha: Cork taint is something entirely recognizable to those in the industry, but wonder how many try a wine, think “ugh” and move on?

Last, there was a short debate: Is Cork Green?

If you dig around a little, you find that yes, cork has been used for hundreds of years because of its unique properties (and because it was somewhat readily available in Old World wine regions of Spain and Portugal) The bark of the cork oak tree regenerates, so bark is carefully removed every 9 or 10 years without damaging the tree itself.

The @Cellar_Sisters provided this link about how green cork is, while @travelprose noted “when I was wine touring in South Africa, many of the wineries chose not to use cork as it was destroying century old trees.”

So there are issues with corks. They likely don’t breathe. Many then responded that agglomerated corks solved many of the failure issues with cork. Let’s look at them next.

Agglomerated (Agglo) Corks

Many folks pointed out that some of these new agglomerated corks had indeed solved the puzzle. New processes ensured almost no chance of cork taint, and yet you still have the romance of removing a cork from the bottle. Indeed as part of the pre-reading material one participant had offered up this link showing that Hugel of Germany had gone 100% to these new agglomerated corks.

@HiddenBench: Diam 10 composite cork offers best of both worlds, cork without TCA and avoids reductiveness and failures of screw caps, Diam 10 composite guaranteed for 10 years minimum. We have moved 100% to this product as of 2012.

Yes, well, we will come back to the reductive issue of screwcaps when it is their turn.

There’s Glue in My Wine?

@Cellar_Sisters asked about how they were held together…which appears to be some type of glue, and wondered “Why would you want that seeping into your wine?”

Makes sense to me…there must be some kind of glue. Off I went then trying to find out what this glue was made from. I found this from Jamie Goode from a while ago:

Closure company Oeneo has also had a lot of success with its DIAM cork. Made of tiny cork granules that have been cleaned by a special supercritical carbon dioxide process and then glued together with synthetic microspheres, it is an attractive, taint-free alternative to natural cork.

Hmm. “Synthetic microspheres”? Are they healthy. More searching yielded no real definitive answer, although one reference I found claimed that this “glue” is the same polymer that contact lenses are made from. So if you are putting them in your eye, you should be OK drinking wine that’s been in contact with it, right (not that I recommend testing this by dropping contact lenses into your next glass of wine…unless you are into practical jokes).

So perhaps agglomerated corks are indeed the best of both worlds. But wait, we haven’t even touched the surface of other closure types yet. Read on.

Screw Caps – Only Good for Chuggables?

Lots of the prep material had linked to articles supporting screw caps as a better enclosure than cork. Ans many members of the chat had similar opinions and started talking about OTR – Oxygen Transmission Rate, which is a fancy term for the objects ability to breathe:

@FortBerens: Stelvin is coming out with new liners with specific OTR and @Nomacorc has managed OTR for long time

@RichieWine: It’s untrue that screw caps do not “breathe”. OTR (oxygen transmission rate) is just different than other closures

@BellaVinho: I have to admit I love how screw caps retain that zip and freshness in my aromatic whites

Of course every product has something wrong with it:

@MBosc: I don’t have strong hands. Sometimes I can’t open a screwcap. Never have issue with natural cork.

@jdiprofio: That said, I have heard of entire and partial batches going bad do to faulty screw caps or caps not sealing.

@Cellar_Sisters: The Spanish governmnt outlawed the use of alt. wine closures in 11 of Spain’s wine producing regions/ DO regulations

As well, much of the reading I did concluded that screwcaps had a tendency to not allow the sulphur in a wine to escape, causing them to appear more reductive. Some cork-loving winemakers I know also support this point. Reductive notes tend to come across as a strong sulphur smell The good news is that with a little bit of open bottle time, these will dissipate, although the initial odour can be enough to turn off an unknowledgeable drinker. (Yes there are counter arguments for how one should deal with this as well).

Summary for screwcaps – I think most agree that they keep wines “fresher”, and there’s been a common opinion that they are best for wines destined to be consumed young.

Synthetic and Plastic Enclosures

I knew we would get lots of opinions on these, as many of the folks I follow on Twitter have very strong opinions on the negative impact of plastic corks (I’ll use that term to cover all man-made materials that look like a cork) on a wine’s quality after any period of aging. From wikipedia: “A 2007 study by Victor Segalen Bordeaux 2 University showed that injection molded synthetic corks allowed the highest levels of oxygen permeation in when compared to natural cork and screw caps, offering the lowest protection against oxidation of the wine.”

@BillMilliken: Synthetic corks destroy white wines prematurely… Should not be used with a wine anyone wants to keep.

Michael Pinkus has had many bottles ruined under plastic:
@TheGrapeGuy: @ErbNWineGirl @TheGrapeGuy @MBosc @UncorkOntario#ONWineCHat Nor should you trust them … I have had plenty of bottles ruined

@Ontario_Wines: IMHO synthetic corks are the worst of ALL choices. Ask @MalivoireWine what happened to their $35 wines back in 01/02/03 #OnWineChat

@Ontario_Wines: They kinda pioneered using Synthetic corks in high end wines in Ont, turned out very bad for their whites #OnWineChat

@billmilliken: @Ontario_Wines @the_pudgy_life #OnWineChat the effect was like it had been a decade in bottle (over the hill) in 18 to 24 months.

Rolph De Bruin thinks synthetics have improved too:
@FortBerens@Ontario_Wines @the_pudgy_life Synth 10 yrs ago was very poor (as was cork with failure rates of 10+%) Techn has improved both #onwinechat

There are improvements being made. Nomacorc has been doing a lot to improve the situation with specific OTR rates for their synthetic enclosures. One stat I saw claimed that they have 11% of the market, and they are producing 2 Billion corks a year, so chances are you are going to come across them regularly (apparently common in California whites). Tom Firth wrote a good article on Nomacorc last fall in Wine Access here.

Glass but not Least

There was very little discussion on glass as an enclosure. The ones I have seen look a little like a port “stopper” cork, although made out of 100% glass, with a circular seal made out of a material similar to a screw cap liner. This gives minimal liner contact with the wine, while sealing the liquid almost entirely in glass.

Very little in terms of pros and cons can be found on the internet, although I did find references to glass being the “perfect seal”, as well as a couple of instances where bottles with glass enclosures leaked when laid on their side for long term cellaring. So much for “perfect”.

The Final Word

This summer we should know more about OTR differences between corks, screw caps, & synthetics after UC Davis completes their study. While no one liked synthetic corks for aging, corks or screwcaps matter less than what’s in the bottle.

@MBosc: for us closure choice is a production decision like oak or stainless
@thegrapeguy:but I still hate getting a bad bottle – but yes when the wine is good I could care less about closure

And finally, Rick Bates likely summed it up best with this tweet:

@Ontario_Wines: My final word: I love everything @UnfilteredEd makes under screw & everything @benchwineguy makes under cork. So I buy both

The End…For Now!