A short position statement on closures

So what's my current position on wine bottle closures? [This is a lenghy post I've just made to an online wine forum, in response to another post.]

There's no such thing as a perfect closure. It's about choosing the best closure available for your wine. If it were a simple matter of 'sealing' a bottle to stop liquid coming out, then of course there would be no excuse for continuing to use cork. There are a range of alternative wine bottle closures that are taint free. Take your pick.

But what we've learned - largely through the adoption of alternatives to cork - is that the oxygen transmission properties of the closure matter. And the precise level of oxygen transmission will affect the way the wine develops after bottling.

For an inexpensive wine that's likely to be drunk within a year or two after release, it's nuts to use natural cork, because cheap natural cork is nasty and carries a risk of taint. For these wines, synthetic corks, screwcaps with a saranex-only liner (there are two different liners for screwcaps, one of which allows very little oxygen transmission - the tin/saran - and one which allows more - saranex only) or Diam represent good alternatives.

Microagglomerates that have been steam-cleaned are also a good bet, although do carry a small risk of taint, as do steam-cleaned one-plus-ones (two discs of natural cork sandwiching an agglomerate core).

For more expensive wines that may be cellared, then it becomes more tricky. I'd say for high end, ageable wines then natural cork bought from the most quality-minded cork producers is the best option. This is because we like the way that wine develops under good natural corks.

I'm personally not keen on the tin/saran liner used widely for screwcaps. It just doesn't allow enough oxygen transmission. This means that there's a risk of reductive problems post-bottling (although the exact nature of this risk hasn't yet been quantified). It also means that the wine will develop differently to the way it develops under cork. Will it be better? How lucky do you feel?

Synthetic corks have developed quite a bit over the last decade to the point where they are claiming really good oxygen transmission characteristics. I'd like to see independent data on this. Likewise with Vino-Lok, the glass closure where the seal is by means of a plastic 'O' ring. It's certainly a functional and good looking closure.

Diam may prove suitable for long-ageing wines. I'm sure it's good for 10 years, because the Altec (the tainted predecessor using the same mechanical design) has shown the physical integrity of the closure is fine after this time.

Finally, a plea - let's try to be as informed as possible when we discuss this complex business of closures. I've found the whole debate to be unessecarily polaized in the past, with people splitting off into factions, and spouting propaganda at each other. For example, when we talk about 'screwcaps', let's remember that the screwcap isn't the closure, but merely a way of holding the liner in apposition to the rim of the bottle. It's the liner that determines the oxygen transmission properties of the closure.

Cork on TV: forest in a bottle

Tonight there's a prime time national TV show all about cork. Titled Cork, forest in a bottle, it's focusing on the environmental impact of abandoning cork for alternative closures such as screwcaps and synthetic corks, and it will be shown at 9 pm tonight on BBC 2.

A quick recap on the issues surrounding corks and their alternatives. Cork is a wonderful natural product, which does a great job sealing wine bottles. It's only as we've moved away from cork to alternatives that we've found that the technical requirements of a wine bottle closure are not all that simple. What cork does (and this seems to be important), is to allow a slow release of oxygen from its compressed cellular structure for the first few months after bottling, and then a very low level of oxygen transmission from then on, through the cork/glass interface. The level of gas transmission by a sound cork seems to be just enough for optimum wine development, but not too much (in reality, it's hardly any at all).

But cork has a real problem: trichloroanisole (TCA) taint. 2,4,6-Trichloroanisole, the major compound responsible for musty taints associated with cork, is formed in cork bark by the chemical combination of phenolic compounds with chlorine. These phenolic compounds are naturally present in bark as a result of the breakdown of lignin, a hard substance giving bark its rigidity. The chlorine can come either from the environment, or from fungi living on or in the bark.

We’re incredibly sensitive to TCA and its chemical relatives, and can detect them at very low concentrations. It makes wines taste and smell musty, like old cellars, or mouldy bread, or damp cardboard. Some people can detect TCA at concentrations as low as 2 ng/litre; others don’t recognize it at 10 ng/litre.

This makes life very hard for the cork industry. There’s no easy way to spot a good cork from a bad one, and so winemakers have either had to resign themselves to losing a certain percentage of the wines they seal with cork to taint, or switch to cork alternatives such as screwcaps and synthetic corks. Many winemakers choose to remain with cork.

The good news for them is that the cork industry is responding to criticism and doing something about natural cork quality, trying to understand the causes of TCA and also to devise ways of removing it.

There are two rather different, yet complementary, approaches to dealing with TCA. The first is to use quality control measures to try to prevent contaminated cork from being turned into closures that then leave the factory. The second is to assume that TCA will be present, and to then remove it by some sort of extractive or washing method – the curative approach. Put both strategies together and substantial reductions can be obtained even if either strategy is not 100% effective alone.

The current rates of cork taint? About 3.3% - this is the figure from the International Wine Challenge faults clinic, which is the world's largest blind tasting, and includes wines from all over the world (this is the percantage of those bottles sealed with natural cork). It's likely that the rate was higher in the late 1980s and early 1990s, but the hope is that as the quality control measures and curative strategies that the leading cork companies have taken begin to show up in terms of lower taint levels, the rate of cork taint should drop to much lower levels.

It is largely because of the pressure put on cork companies by the success of alternative closures that these strategies have been put in place. Without alternative closures as competition, it is likely that we'd be stuck with much higher levels of cork taint. Winemakers have a responsibility to source cork only from those companies that are serious about combating taint.

The future? Cork is a wonderfully sustainable product with a low carbon footprint. The cork forests really are beautiful, and because wine stoppers are the most profitable use for cork, using cork this way sustains rural communities and helps preserve these ecosystems. But the wine industry can't take the hit that it was taking in terms of ruined bottles in the late 1990s all in the name of sustainability. If the rate of cork taint really is on the way down, then there's certainly a future for cork, but as just one of the closure solutions alongside a range of alternatives.

What has saved cork so far is that fact that sealing a wine bottle so that the wine tastes good when it's opened isn't a trivial matter of just 'sealing' it. If screwcaps, for instance, did exactly the same job as cork, then it would be stupid not to switch straight to screwcap for all wines: they don't have musty taint issues, and they are a lot more convenient because you don't need a device to open the bottle.

Insolite: a lovely Loire Chenin

Loire Chenin Blanc is geek territory. Chenin is a fabulous grape, but it's not for the masses - it requires quite a bit of investment on behalf of the drinker, in terms of understanding it and learning to love it.

Here's a good one. Appley, minerally, a bit tangy, with some notes of cider (in particular, it has a bit of tannic bite like you get with bittersweet cider apples). Perhaps that is one reason that Chenin can age so well - it's a white wine with tannin.

Thierry Germain Domaine des Roches Neuves 'Insolite' 2006 Saumur, Loire
Fantastic stuff from old vine Chenin Blanc. Notes of honey, spice, apples, vanilla and dry straw on the nose. The palate is savoury and vivid with fresh green apple and lemon acidity and concentrated herb and straw savouriness. Extremely fresh with real cut and bite: this needs food, really. A complex savoury wine with a bit of bite. 91/100 (around £13, Les Caves de Pyrene, artisanwines.co.uk, Wimbledon Wine Cellar, RSJ)

As an aside, it's interesting to compare the corks from this and the Sottimano I mentioned here recently. The Sottimano looks like it is unbleached. The Insolite shows something I often find in sweet wines, and also Chenins - the wine seems to have eaten into the end of the cork, softening it. Is this the acidity? (see below)

Another corked wine: the lenticels?

Another corked wine tonight (not that I'm getting many these days). I looked at the cork - once again, it had angry looking lenticels. I'm beginning to thing that the lenticels are the source of the problem with corks: where they run across the face of the cork, does this increase the chance of cork taint? Interestingly, this tainted wine had some mustiness, but also some sweek oaky notes (even though this was an unoaked rose).

Making corks

Spent yesterday morning at Amorim's labs with Dr Paulo Lopes, who's a scientist working on issues such as oxygen transmission by closures. It sounds nerdy and dull, but it's really important. Paulo did a presentation on efforts by Amorim to deal with the taint issue, then he presented his work on how much oxygen ingress there is with each type of closure.

Then it was time to see a couple of cork manufacturing and processing plants. High-end corks are still punched by hand (top picture), a skilled task where rapidly taken decisions about where to punch the next cork from have important quality implications. The corks are then sorted either automatically, or manually (above). The best quality corks can cost more than a Euro each (below) - and they look beautiful. The modern cork production process is a fusion of the modern (e.g. gas chromatography screening for minute TCA levels) with the traditional (cutting cork bark, hand punching corks).

I love Portugal...

Post from the road. I'm in Portugal, this time with my family. As well as visiting solo on several occasions, I've been here with Fiona a couple of times before, but this is the first time we've brought the kids along, and I'm really glad we did. There's something special about this country that I wish my two boys could 'catch' a little of.

The reason behind the visit is to learn more about cork and its production, courtesy of the leading cork producer in the world, Amorim. I'm keen to find out more about the sorts of measures that Amorim are taking to eradicate taint issues, which still haunt the industry, and also about the natural cork-based alternative closures they are marketing. I'm also looking at issues such as sustainability, which are of great current interest.

It's the first time I've really tried to juggle a work trip and a family trip in this way. It's fraught with danger, in the sense that if Amorim were to foot the whole bill this would be a significant conflict of interest (rather than just a mild one). I guess the only way to deal with this problem is to be honest, and disclose any such information, and trust that readers realize that at all times, I'm trying to deliver the best, most balanced, most informed perspective on any particular issue that I'm writing on.

After all, my reputation, and thus my future earning potential, depends on this. If gathering data means spending time with winemakers, staying in their homes, eating dinner with them, having flights paid for, and receiving samples, all in order to get the best perspective and inside line on any particular story and issue, then as long as it is disclosed, it is not a huge problem. It's the undisclosed, behind the scenes deals that are worrisome. And for me, in half-term week, being able to combine family time with work on the road is hugely advantageous.

Last night we stayed in the Alentejo at Monte dos Arneiros. It's a beautifully quiet, secluded country retreat just an hour's drive from Lisbon, and we liked it so much we intend to go back there in the near future. While I visited Amorim's plants at Coruche, the kids and Fiona swam and rode bicycles through the 500 hectares of cork oak forest that this property manages. Food was authentic local fare, presented without any fuss or pretension. The weather was atypically cool and damp, but we still had a good time.

Tonight we are staying in Espinho, at the Hotel Solverde. It's on the coast, some 18 km south of Porto, and despite the dire account of Espinho in the Rough Guide, it seems quite a nice spot - well, at least, the hotel is rather plush and well managed, boasting indoor and outdoor pools, a spar, and a helicopter pad. We haven't hit the town, yet.

Much merriment was had this evening when we checked out the indoor pool, and were told that we had to wear swimming hats. All of us. We purchased these from the spa reception - elder son chose pink, younger son red, I was yellow and Fiona was blue. They made us all look very daft indeed, and it reminded me of the time when we fell foul of French swimming pool laws that insisted on males wearing speedo-style trunks and not swimming shorts (so, as a mark of protest, we swam in our briefs, which was, rather strangely, allowed).

Tonight we dined on room service and ordered some wines from the restaurant list. Even in a five-star joint like this, you can drink well reasonably cheaply. The wine list had some good names (alas, no vintages or descriptions), but we enjoyed the Quinta das Bageiras 2003 Bairrada (good, complex, earthy, spicy Baga that tastes wonderfully natural and traditional) and the Casa de Togeira Vinho Verde 2007 (laser-sharp, crisp and attractively fruity). The former was 17 Euros, the latter just 11.

Tomorrow I meet with Amorim's technical expert Miguel Cabral, and then we're off to Antonio Amorim's home for dinner with the kids. I really hope they behave themselves. His kids are of similar age, and ours have been sternly warned...