A small mystery

Tonight's wine mystified me. It smelled and tasted really good on opening the bottle, but an hour later, with dinner, it was acidic and not really very pleasant. Nice color and aroma, and even with the strangeness, it was Rhonish.

The bottle was David Coffaro Terre Melange 2002. David was using an artificial cork of some sort of foam material at that time. The wine was absolutely NOT corked! Nothing like that. More like it was "turning", and yet I don't think I've had a bottle that was doing something like that in 30 years, if ever.

Any ideas? There's more and I'll look again tomorrow.

It's a Dry Creek Valley wine, estate bottled, and unfiltered and unfined. 56% Carignan, 22% Petite Sirah, 15% Mourvedre, 7% Syrah. 13.9% alcohol. 170 cases.

John, I've had some bad luck with plasticorks and the like. I've had numerous bottles under synthetic cork that seemed to have the fruit stripped from them. Opponents of fake cork often cite that the seal isn't tight enough and allows too much air to be exchanged. The fact that the wine tasted good immediately upon opening and then got worse is odd though.

It got worse overnight. A lot worse. I darned near spit out the taste, and I opened another bottle of something else for dinner tonight.

Gack.

Don't you hate that with a supposedly good wine. I have it happen more than I like to admit with wines with real corks and plastic. I think it has more to do with how the wine has been stored. And then some wines just aren't meant to last as long as we like.
I had a nice shiraz supposedly and it was just bad after a few glasses. I have a good relationship with my wine store and they replaced with another of the same and it was great.

[Robin Garr]

John, sadly, this seems to happen with non-trivial frequency with the plastic corks ... I had a stash of 01 Texier Rhones that just went dead after three or four years, and I've talked with a number of geek types (including David Schildknecht), who concur. Stuart may be able to enlighten us on more recent developments, but based no experiences and anecdotal reports over the past few years, I'm no longer comfortable keeping wines under plastic more than three or four years.

Glad to see this consensus growing on funny things sometimes happening to wines under plastic corks. Some whites thusly bottled have had strange vinyl-like whiffs in my experience, while many reds bottled under plastic have been just as described - thin and acidic, sometimes tinny. I can't explain it, but it does make me dislike those closures quite a bit.

Cork taint aside, if it isn't a high-quality solid cork, then screwcaps or even the rare but elegant glass stoppers are just fine with me.

Robin,
There was a well-publicized finding some years ago that some artificial corks reacted with SO2, thereby promoting premature oxidation. I don't remember which of the artificial corks had this problem, and I believe that at least one manufacturer has attempted to rectify the situation. No doubt, as you say, Stuart could set us all straight in this matter.

Mark Lipton

Practical Winery & Vineyard published a study on "Oxygen Transmission Through Different Closures into Wine Bottles" in their July/August issue.

Maybe someone has that lying around.

I keep a copy right next to my copy of "A Practical Approach to Sixteenth Century Counterpoint".

rwj

Looks like I'm going to be going through my pre-'04 Coffaros.

I thought that all of the plastic closures were known to fail after at most 3-4 years, although that doesn't explain the wine in question. But AFAIK no plastic cork will for work for extended aging.

That's weird.

I'm a mechanical engineer by profession, which means I tend to believe in evidence, as opposed to "received wisdom".

Why should plastic closures "fail", and in what way would they "fail"? In asking in what way, I don't just mean "the wine goes bad", but what failure in the closure causes the wine to die? Is it some chemical in the plastic that reacts with the wine? Is it some characteristic of the plastic closures that causes more transfer of air or other molecules between the inside and the outside?

Cork is obviously the standard against which other closures must be compared. Yet corks aren't perfect. Corks are surely part of the cause of "corked" bottles. And I'm no fan of accelerated aging tests, having had to design and conduct them, and then explain how they don't compare exactly to real life.

Good golly, what a challenge!

John,
As I previously said, the problem has been associated with a rapid loss of SO2 in the wine. What reaction is occuring? My guess, as an organic chemist, is that polystyrene foams could react with SO2 in the acidic medium of wine, undergoing electrophilic aromatic substitution to produce an aryl sulfinic acid. Of course, I have no idea if those fake corks are made from polystyrene, polyurethane or something else entirely, so take that speculation for what it's worth.

Mark Lipton

John,
As I previously said, the problem has been associated with a rapid loss of SO2 in the wine. What reaction is occuring? My guess, as an organic chemist, is that polystyrene foams could react with SO2 in the acidic medium of wine, undergoing electrophilic aromatic substitution to produce an aryl sulfinic acid. Of course, I have no idea if those fake corks are made from polystyrene, polyurethane or something else entirely, so take that speculation for what it's worth.

Mark Lipton

Mark, how much SO2 would be necessary for a reaction like that that to take place? And would the pH of the wine change the results? I ask because most of my problems have come from wines with a low pH, but usually wines high in acid need less SO2 for preservation. I wonder if there are certain types of wine that are more susceptible to this problem (if that's what it is.)

Mark, how much SO2 would be necessary for a reaction like that that to take place? And would the pH of the wine change the results? I ask because most of my problems have come from wines with a low pH, but usually wines high in acid need less SO2 for preservation. I wonder if there are certain types of wine that are more susceptible to this problem (if that's what it is.)

Bill,
Any SO2 at all will react. The time scale involved (months to years) is enormous for most chemical reactions (typically, we run reactions for a few hours at most) so even a low level of SO2 has sufficient time to react. The reaction is probably faster at low pH since acid should catalyze the reaction. Please note, though, that I first encountered this problem in a Siduri Pinot Noir that no one would accuse of being terribly acidic.

Mark Lipton

My guess, as an organic chemist, is that polystyrene foams could react with SO2 in the acidic medium of wine, undergoing electrophilic aromatic substitution to produce an aryl sulfinic acid.

So you're guessing there's something in the foam that converts the sulfites in the wine into acid, and not a "good tasting" acid at that. (Trying to translate into words that have meaning to me.)

Could be. The cork is made of a very dense foam inside a tube of a solid flexible plastic material. The pore size of the foam is somewhere around 0.1 mm. It appears to be a closed-cell foam. I cut the cork in half and the wine didn't penetrate more that about 0.2 or 0.3 mm. It looks to me like a polyurethane, and its texture is elastomeric. It could be a self-skinning polyurethane extrusion, cut into lengths.
I dug out the camera and tried the "macro" setting for the first time. The camera didn't do exactly what I wanted, but the pictures show what I can see with my eyes.

My guess, as an organic chemist, is that polystyrene foams could react with SO2 in the acidic medium of wine, undergoing electrophilic aromatic substitution to produce an aryl sulfinic acid.

So you're guessing there's something in the foam that converts the sulfites in the wine into acid, and not a "good tasting" acid at that. (Trying to translate into words that have meaning to me.)

Well, the acid produced is a modification to the surface of the foam, so removal of the fake cork removes the acid as well. The main consequence of this reaction is the removal of SO2, an antioxidant, from the wine, rendering it more susceptible to oxidation.

Could be. The cork is made of a very dense foam inside a tube of a solid flexible plastic material. The pore size of the foam is somewhere around 0.1 mm. It appears to be a closed-cell foam. I cut the cork in half and the wine didn't penetrate more that about 0.2 or 0.3 mm. It looks to me like a polyurethane, and its texture is elastomeric. It could be a self-skinning polyurethane extrusion, cut into lengths.
I dug out the camera and tried the "macro" setting for the first time. The camera didn't do exactly what I wanted, but the pictures show what I can see with my eyes.

Yeah, the properties of those fake corks that I've seen resemble polyurethane foams more than anything else I've seen, but polymer engineering accomplishes things I often find surprising. Assuming for the moment that it is a polyurethane elastomer, they usually have aromatic rings that can undergo the reaction I described; in fact, they should be more reactive than the rings in polystyrene.

Mark Lipton

That's weird.

I'm a mechanical engineer by profession, which means I tend to believe in evidence, as opposed to "received wisdom".

Why should plastic closures "fail", and in what way would they "fail"? In asking in what way, I don't just mean "the wine goes bad", but what failure in the closure causes the wine to die? Is it some chemical in the plastic that reacts with the wine? Is it some characteristic of the plastic closures that causes more transfer of air or other molecules between the inside and the outside?

Cork is obviously the standard against which other closures must be compared. Yet corks aren't perfect. Corks are surely part of the cause of "corked" bottles. And I'm no fan of accelerated aging tests, having had to design and conduct them, and then explain how they don't compare exactly to real life.

Good golly, what a challenge!

John,

As I understand it the various kind of plastic stoppers fail in the sense that they don't maintain a tight seal for more than 3-5 years. The rigid plastic plugs are more like 1-2 years (I've seen white wines with obvious browning after 3 years, for example). As I said, the manufacturers don't suggest these stoppers for long-term aging, at least in most cases.

My dad is a materials scientist (polymers mostly), and I was having a glass of wine with him and a colleague when the topic of cork came up. They said that cork has the unusual physical property of being able to be compressed a lot, and then springing back almost completely to its former dimension and holding that dimension.

I don't doubt the chemical theory for loss of SO2, but there's certainly a simpler reason for at least part of this loss: failure of the seal leading to oxygen transmission past the closure. Maybe Occam's Razor at work here. It's hard to imagine that the manufacturers would have been so negligent as to use a material that is reactive with the main preservative in wine.

That's weird. I'm a mechanical engineer by profession, which means I tend to believe in evidence, as opposed to "received wisdom".

Why should plastic closures "fail", and in what way would they "fail"?

Believe me John, I've been there. If only all of reality fit our existing models, though.* There's a phenomenon (visible on ERP forum for instance) of wine-enthusiast scientists denying that this or that observation could possibly be true because it doesn't happen to fit their theoretical understanding ...

However, to play devil's advicate, it also could just be the wine in this instance, regardless of closure, even if there also is a consistent problem with these corks.

*In a famous article -- Atlantic Monthly early 1990s I think -- examining modern economic theory, some academic economist views were summarized as "if the world doesn't fit our model, so much the worse for the world!"

It could be the bottle. That was my last bottle of Terre Melange '02. Two years ago, I likened a bottle to a Cote Rotie.
I do have bottles of other blends from David Coffaro of the 2001 - 2003 vintages - Estate Cuvee (Zin, Cab, kitchen sink), Block 4 (field blend, Zin, Petite Sirah, kitchen sink), and Aca Modot (Cab, Merlot, etc.). I suspect, the way these things go, if I don't report anything, then I won't have found a problem with them. <g>

Here's a datum, or perhaps two data points.

I opened a bottle of Coffaro Block 4 2001 tonight. Same kind of stopper.
Tastes just like what it is. Nicely mature, pepper from the PS, bramble from the Zin, the moderations of a few years, very smooth, tannins pretty well but not entirely gone. 40% Petite Syrah, 40% Zin, 20% other. Field blend. 300 cases.

I had another bottle of that just two months ago, on October 20. The tannin is mostly gone, leaving a bit of an acid balance. Time to drink up.

Could be stopper variation.

Tonight's wine was very enjoyable and didn't change unexpectedly over a couple of hours. It opened up and showed more fruit and seemed a bit riper, but this bottle wasn't acidic at all.

This wine cost $18.50 on futures, a ton of bucks for Coffaro! But it's a good example of what could easily cost twice that at a store.

Perhaps I just got a bummer with the Terre Melange.

I thought that all of the plastic closures were known to fail after at most 3-4 years, although that doesn't explain the wine in question. But AFAIK no plastic cork will for work for extended aging.

Jeez, I thought everybody knew: The plastic cork makers know perfectly well that their corks don't provide sufficient vapor barrier, and (as far as I 've ever known) concentrate their efforts on wines in the DYA (drink youngest available) category, which is of course quite large enough to be economically viable...which information would not prevent some idiot from selling the corks to a producer of ageable wines anyway...