A Visit to Amorim: Progress with Cork

“It’s very upsetting when people come and try to kill you. We’ve had two funerals already. But when you have 70% of wines under cork, I think you can see that after fifteen years the debate has been resolved,” Carlos de Jesus started our meeting at Amorim.

I had taken advantage of my trip to Douro and the Dão to visit Amorim’s plant just to the south of Porto. Half of the world’s corks come from Portugal, Amorim has more than a third of the market, and roughly two thirds of business is in wine stoppers. There’s a plant farther south, near the forests, when the first processing is done, and then the sheets of cork are sent to the plant in the north to be turned into corks.

Amorim1Sheets of corks come from the south

We visited the plant where both agglomerated corks (made of small particles) and solid corks (punched out from the sheet) are made. It’s actually technically easier to remove TCA from agglomerated corks, because the broken up particles can be heated to extract it before they’re stuck together into the cork. There’s a whole hall with a vast series of machines taking in raw cork and spewing out finished corks.

Amorim3Raw cork goes in one end and agglomerated corks, free of TCA, come out the other end

To make solid cork, the sheets are cut into bars of the right width, and then the corks are punched out. There are two separate parts of the plant devoted to this, one automated, one manual. Watching the operators of the manual line seems like a time warp. They hold the bar in a machine, operate a treadle to punch out the cork, and then move the bar along to punch out the next cork. This seemed old fashioned compared with the automated equipment, but Carlos explained that the operator gets better results, just like manual grape harvest is better than mechanized!

Amorim5Corks being punched out of bars on a automated line

After visiting the plant, we walked over to Amorim’s research facility, in a small building close by. The R&D department was created in 2000. A main objective is to find solutions to the TCA problem, but they’ve also been investigating the route for oxygen to enter bottles.

I was quite surprised when researcher Paulo Lopez explained that the routes for ingress are different for different closures. For synthetics and screwcaps, it’s permability from the exterior, but for cork it is the oxygen contained within all those little cellules in the cork itself. (Presumably this applies unless and until the cork loosens, but experiments show that this doesn’t happen in the first few years.)

Paulo says that the TCA problem is being significantly reduced. In 2003 the average TCA was 2.68 ng/l, now it is 0.62 ng/l. “We consider 0.5 ng/l to be zero as that is the limit of detection by available equipment. 1 ng/l is the sensitivity of the most sensitive human tasters.”

The lab does Q & A, testing 800 samples per day for TCA. This requires 24 hours to soak the cork and then 24 hours to get results. So it’s a check, but they have to wait 48 hours to release each batch.

Amorim7Serried ranks of gas chromatographs in the lab

The latest system is NDtech, which analyzes individual corks. (If not secret, it’s certainly more closely guarded as no photos were allowed here.) Eight years in development, NDtech basically takes the gas chromatography system to automated speeds. A single production line can handle about 15,000 corks per day, and it costs 15¢ per cork.

Each line spews corks out into one of three bins: guaranteed below detection; at the edge of detection; and not acceptable. It didn’t look casually as though the second bin was that much less full than the first (the third was much smaller), but Paolo says the proportions are 65%, 30%, and 5%. “There are still too many false positives,” he says, “the next stage is to reduce them.”

It was a major feat to automate the equipment to this point, but capacity is still limited. There will be about 15 million NDtech corks this year and 60 million next year, which is probably way below demand. “Looking at individual corks is the holy grail. NDtech analyzes individual corks, but I doubt that we’re going to apply it to billions of corks. We’ll start with 50 million corks and then we’ll scale up. We’re not here to defeat TCA and go out of business. We need to defeat TCA and stay in business,” says Carlos.

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Experiments at Chateau Margaux: fining, filtration, and closures

You might think that once a wine has gone through alcoholic and malolactic fermentations, and been matured for months in oak barriques, that the die was set. Not a bit of it: the continuing experiments at Chateau Margaux show that there is an effect from every stage of what I suppose you might call finishing procedures. “Once again it is impossible to deny the differences, which is somewhat frightening,” was Paul Pontallier’s comment at the end of the tasting.

Once simply part of the routine of producing red wine, fining has become somewhat of a controversial issue, and is now one of the most obvious differences between Old and New World. When I was discussing Cabernet Sauvignon with producers in the course of researching my book Claret and Cabs,  virtually every producer in Bordeaux told me they fine, and almost all producers in Napa Valley said they avoid fining just like filtration.

Fining was introduced as a procedure to lighten the wine, the traditional process being to add egg whites to the barrel. Albumin protein in the egg whites is positively charged, and so reacts with negatively charged tannins to precipitate them. The conventional argument is that this softens the wine by removing harsh tannins and also polishes it by taking out other components. Critics ask why the egg whites should act only on harsh tannins and take the view that desirable tannins and other components might equally well be affected. And, of course, over the past ten or twenty years, tannins have become much riper so you might well ask whether they still need to be removed. (Most producers who continue to find do use fewer egg whites now than they used to.)

Well, the answer at least in the context of Bordeaux, is absolutely clear: the 2004 Chateau Margaux fined with 6 eggs tasted like a completely different wine from the unfined example. Some people thought they could see a difference on the noses of the two wines, but personally I thought they were indistinguishable (and I am a bit hard put to see why volatile compounds might be removed by fining). But the unfined example had more evident tannic grip, less finesse, and came up just a little shorter on the finish. The fined sample simply gave a distinctly more polished impression, not just because of less tannin, but with a sense of being altogether better rounded. Chateau Margaux as you will find bottles in the shops, by the way, has been fined with 5 egg whites per barrel since 1996.

Filtration seemed to have less effect, as tested by comparing unfiltered Chateau Margaux 1995 with sterile-filtered wine. There was no detectable difference on the nose, and the balance on the palate seemed very similar. The main effect to my mind was that the sterile-filtered example seemed like a slightly older, more developed wine, with a touch of sous bois that was not evident on the unfiltered wine. Most participants preferred the second wine, but that depends somewhat on whether you prefer your wines younger or older. Paul Pontallier felt that the filtered wine had actually deteriorated a little due to a touch of oxidation. I can’t say that I would describe the filtered wine as eviscerated or having lost character as a result of filtration, but I suppose it might be the case that the filtration removed components that protect against oxidation.

The closure trial compared Pavillon Rouge 2002 sealed with natural corks with the same wine sealed under screwcaps. There had also been a trial with synthetic corks, but apparently the results were disastrous, and in relatively short order the wine was spoiled. “It’s a good decision to use screwcaps for white wines that will be drunk in the first six months,” says Paul Pontallier, “and with what I know now I would do the same, but our dilemma is that we want to make wine that will age.” The two wines were quite different: open, round, and fruity under cork, but reserved, backward, and showing more austerity under screwcap. Interestingly, the participants split more or less equally as to which style they preferred.

Chateau Margaux is just about to undertake the construction of a new experimental cellar that will allow them to undertake even more experiments. Among future projects are looking into the properties of individual clones of grape varieties and investigating the effects of different types of pressing. “To my astonishment, many people take the view that, if it is new, it must be better,” says Paul Pontallier, “I admire their optimism, but I feel the need to experiment first.”

An Experiment with Corks and Screwcaps

It’s years since I did a scientific experiment but there is one I would like to see done with corks and screwcaps. It’s quite amazing that even with a more than a decade’s experience of bottling wines under screwcaps, the long term effects of the type of closure remain controversial. One issue that I think should be finally resolved is just what effect exposure to oxygen has on long term maturation.

When the same wine is bottled both under cork and under screwcap, it’s evident within a few months that they develop differently. Most of the comparative tastings that I have done have been with white wines, where the usual difference is that wine under screwcap retains brighter fruits with more evident freshness. Preferences are usually split at such tastings between the bottlings: some people prefer the fresh, young style of screwcaps, while others find more complexity in the greater development of the wine under cork.

When I was out in New Zealand and Australia earlier this year, I had several opportunities to compare older red wines that had been bottled under both types of closure. The results were completely consistent.  The wine under screwcap always seemed younger – in a blind tasting you might have said by a couple of years – with more primary fruits, whereas the wine under cork showed some development towards more savory, sometimes even tertiary, aromas and flavors. All of these wines were Pinot Noir (mostly from the first few years of this millennium) but I assume the results would be generally true for all red wines. (The tastings are described in more detail in my recent book, In Search of Pinot Noir). This may not be a completely fair comparison, because the reason for the switch to screwcaps was often the terrible condition of the corks available down under. In fact, when there was the opportunity to taste multiple bottles under cork, they often tasted as different from one another as they did from screwcap, an immediate validation of the decision to switch to screwcaps.

So wines under screwcap clearly develop more slowly: the question in my mind is whether they develop in the same way at a slower pace or whether the overall pattern of  development is different, reflecting a different relative timing of the loss of primary fruits and the appearance of tertiary flavors. Among the wines I tasted, when the wines under cork were in perfect condition, I generally preferred them: but that may be because my taste generally runs to older wines. I would be really interested to repeat the comparison in a few years when the screwcap wines have developed further to see which I prefer then.

Anyway, back to the experiment. The difference between screwcaps and corks is the rate with which oxygen gets into the bottle. It can be close to zero for screwcaps: in fact, there have been problems involving reduction for wines bottled under screwcap, just as damaging in their way as problems with oxidation for wines with faulty corks. Sulfur levels need to be reduced when bottling under screwcap and it may take a while to establish the most appropriate levels for wines intended for any aging. The very best corks (defined operationally as the tightest) have very low oxygenation levels close to those of screwcaps. But the unanswered question is whether you do actually need some level of oxygen exposure; for corks this comes from the supposed “breathing” of the cork; for screwcaps it could come in the future from liners with defined rates for passage of oxygen.

So the experiment I want to do is to determine definitively whether the difference between corks and screwcaps is solely due to oxygen exposure. It is very simple in principle. Bottle a (red) wine under both cork and screwcap. Take bottles with each type of closure and keep one set in normal cellar conditions (cool, dark, humid). Put the other set under identical conditions but in an atmosphere of nitrogen. Then see whether the wines with cork and screwcap closures develop in exactly the same way under nitrogen (which is what you would expect if oxygen is the sole relevant factor). And of course see what differences emerge with and between the wines in the normal cellar. All that’s required is a cellar filled with nitrogen (and I suppose a means of retrieving bottles for periodic testing). Then finally we would know the answer instead of speculating and arguing about it.