Less than 1% of wines corked?

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N Weis
 
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Less than 1% of wines corked?

Post #1  Postby N Weis » August 20th 2009, 5:07pm

Haven't seen my new issue of Vineyard & Winery Management yet, but apparently there is an article in it written by Christian Butzke on the incidence of cork taint in the Indy Wine Competition. WS article here (subscriber limited, sorry):

http://www.winespectator.com/webfeature/show/id/40516

Doesn't sound like a particularly scientific study, and no analysis - merely reporting by judges.

I'll keep my thoughts to myself since, well, what's the f-ing point? Everyone disagrees on the number anyway, with those who use cork trying to minimize it and those who don't grinding their own axe (unfortunately, we all need to either use cork or don't, and justify that accordingly).

Interesting to me was this tidbit:

Yet research into the science of cork taint indicates that the two results may not be mutually exclusive. The explanation for that paradox revolves around TCA itself. According to Ron Jackson, author of Wine Science: Principles and Application, a person's ability to detect the presence of TCA varies so widely that the percentage of bottles identified as corked could swing wildly depending on who was doing the tasting.

"For 99 percent of people to detect TCA, you're talking a concentration in the range of 200 to 300 parts per million," said Jackson. "For 50 percent or more of people to detect it two-thirds of the time, the value is in the range of 5 to 7 parts per billion. But some people can detect concentrations as low as single parts per trillion." Unfortunately, even when TCA levels are too low to detect, they can ruin a wine—at low concentrations the chemical deadens a wine's fruity flavors and aromas.


So, threshold varies from 2 ng/L to 300,000,000 ng/L? Are we including anosmics?
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Re: Less than 1% of wines corked?

Post #2  Postby Bill Tex Landreth » August 20th 2009, 6:42pm

I have been running about five percent in the past few months.
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Re: Less than 1% of wines corked?

Post #3  Postby Brian G r a f s t r o m » August 20th 2009, 7:37pm

My personal experience has been around 1-2% ... then again, there's probably a handful of other "kinda corked" wines that I don't identify as "kinda corked," but rather just "not that great of a wine" because that's the only bottle I've ever had of that wine (no baseline to compare against).
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Re: Less than 1% of wines corked?

Post #4  Postby Paul Starr » August 20th 2009, 9:11pm

For the periods I've kept tallies, I've had between 2% and 8% of cork sealed wines turn up with closure-related faults (TCA, oxidation, mould, cork flavour). I'll still buy some wines under cork (Italians, Spaniards, bubbles mainly) where I don't have a choice of closure, but wish it were a better seal.
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Re: Less than 1% of wines corked?

Post #5  Postby michael dietrich » August 21st 2009, 9:02am

I unfortunately seem to be very sensitive and have been running about 8 %. I do feel that it is coming down some. I seldom go through a week without finding some corked wines. I have been impressed with this Diam cork that some people are using. They say maybe 1 bottle in a million. My count is now up to 201 bottles with that closure and no hints of TCA. I still love those Stelvins for lots of wines.
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Re: Less than 1% of wines corked?

Post #6  Postby Michael O'Brien » August 21st 2009, 9:40am

I started tracking this only about 13 months ago and I am running at approx. 4%. The corked wines are coming from several sources but mostly direct from the wineries.
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Re: Less than 1% of wines corked?

Post #7  Postby Chuck Miller » August 21st 2009, 12:44pm

study wrote:"For 99 percent of people to detect TCA, you're talking a concentration in the range of 200 to 300 parts per million," said Jackson. "For 50 percent or more of people to detect it two-thirds of the time, the value is in the range of 5 to 7 parts per billion. But some people can detect concentrations as low as single parts per trillion." Unfortunately, even when TCA levels are too low to detect, they can ruin a wine—at low concentrations the chemical deadens a wine's fruity flavors and aromas.



This is just BS. The human threshold is several parts per trillion. The idea that is takes 200-300 parts per million for 99% of people is just ludicrous. Not only that, the second sentence totally contradicts the first. If 99% require 2-300 PPM to detect, how can half of the people detect it 2/3 of the time at 5-7 PPT???

I am cursed with being very sensitive, my guess is in the 4-5 PPT range, and know one or two people that are probably more 2-3 PPT. For me, approximately 5-8% of wines are corked. Interestingly enough, in the past week, a 2000 Ramonet Montrachet, a half btl of 98 Beaucastel and a bottle of Scotch sealed with a T-top were all corked.
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Re: Less than 1% of wines corked?

Post #8  Postby larry schaffer » August 21st 2009, 5:45pm

Hogwash . . . the darned article is hogwash, I tell you!!!!!

Seriously, as Nate points out, it is FAR from a scientific study . . .

We just did cork trials at Fess Parker with a very well respected cork producer, and our best lot had about 4% TCA and about 6% 'other off aromas' . . . .

The worst lot - and understand that the cork co. KNOWS we are testing for TCA and it would therefore behoove them to get the best darned lot to us . . . if they COULD - had over 15% TCA and another 10-15% 'other off aromas' . . .

Are things 'getting better'?!?!? Maybe, but from a winemaker's perspective, it REALLY SUCKS to put 2 years of work into a wine only to see it 'ruined' quite quickly by a 2" piece of cork . . .

Just another data point . . .

Cheers!
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Re: Less than 1% of wines corked?

Post #9  Postby N Weis » August 25th 2009, 7:21am

larry schaffer wrote:Hogwash . . . the darned article is hogwash, I tell you!!!!!

Seriously, as Nate points out, it is FAR from a scientific study . . .

We just did cork trials at Fess Parker with a very well respected cork producer, and our best lot had about 4% TCA and about 6% 'other off aromas' . . . .

The worst lot - and understand that the cork co. KNOWS we are testing for TCA and it would therefore behoove them to get the best darned lot to us . . . if they COULD - had over 15% TCA and another 10-15% 'other off aromas' . . .

Are things 'getting better'?!?!? Maybe, but from a winemaker's perspective, it REALLY SUCKS to put 2 years of work into a wine only to see it 'ruined' quite quickly by a 2" piece of cork . . .

Just another data point . . .

Cheers!

So you guys soaked and tested individual corks for TCA? How many? Or are you self-reporting on sniff tests as well?
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Re: Less than 1% of wines corked?

Post #10  Postby Bill Tex Landreth » August 25th 2009, 7:35am

Had a mildly corked bottle last night. Considering the number of wines in the past month both here and in Napa, I am running at 0.2% or so for August.
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Re: Less than 1% of wines corked?

Post #11  Postby Tom Hudson » August 25th 2009, 7:57am

At my 76 seat restaurant/wine bar, 75%+ of the wine we sell is BTG.

Our corked rate is about 1.5% of those with corks. Our bottles with corks are down to less than 75% now, with screw caps, vino locks, etc. constantly increasing.

IMHO, many of the wines identified as corked are actually heat damaged. Yes, the wines are flawed, but not by the cork.

Since I'm very anal about storage/shipping conditions, we only purchase from the minute portion of importers/distributors who guarantee tempurature control throughout the shipping process.

This is why I believe our failure rate for returned bottles is less.
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Re: Less than 1% of wines corked?

Post #12  Postby larry schaffer » August 25th 2009, 8:50am

Cheers![/quote]
So you guys soaked and tested individual corks for TCA? How many? Or are you self-reporting on sniff tests as well?[/quote]

Nate-

We got 250 count sample bags; we randomly selected 100 corks from each 250 bag sample; we put these into jars with tin-lined caps and soaked each for approx. 36 hours; we then poured them into glasses and 4 of us walked around and smelled each glass; If at least 3 of us felt the sample showed signs of TCA, it was noted as having TCA . . .

We did NOT send any samples off to ETS or Vinquiry for further study, trusting our noses to determine what we wanted to do . . .

Curious to hear your feedback on our protocol and our findings . . .

Cheers!
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Re: Less than 1% of wines corked?

Post #13  Postby N Weis » August 25th 2009, 12:00pm

Just curious.

You made it sound as though your problem was in the sniffing and self-reporting by wine judges who tasted 3,500 individual bottles and designated <1% of them as corked. How many were false positives? How many corked bottles slipped through the cracks? We'll never know I guess. No analysis.

I don't have all the answers, so no comment on your protocol. Each winemaker needs to do things in a way that makes them feel comfortable and confident in what they're purchasing. One thing I always wonder when sniffing or looking at SPME of multi-cork soaks is what the breakdown is. One cork at sky-high levels? Baseline low level? In between?

One problem is the lack of feedback through the system. For this reason, I like to talk to high-volume tasting rooms who train and test their staff for sensitivity and have their supplier brand their corks and then track bottles opened by supplier and rejected bottles by supplier.

For another data point, I talked to one such winemaker recently who does this at his high-volume TR. His best supplier was 0.5%. His worst was 1.5%.
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Re: Less than 1% of wines corked?

Post #14  Postby Chuck Miller » August 25th 2009, 4:07pm

Tom Hudson wrote:At my 76 seat restaurant/wine bar, 75%+ of the wine we sell is BTG.

Our corked rate is about 1.5% of those with corks. Our bottles with corks are down to less than 75% now, with screw caps, vino locks, etc. constantly increasing.

IMHO, many of the wines identified as corked are actually heat damaged. Yes, the wines are flawed, but not by the cork.

Since I'm very anal about storage/shipping conditions, we only purchase from the minute portion of importers/distributors who guarantee tempurature control throughout the shipping process.

This is why I believe our failure rate for returned bottles is less.


Tom, no doubt that your purchasing thru importers/distributors that temp control will result in fewer cooked bottles and therefore a lower return rate. But I take exception to your opinion that 'many of the wines identified as corked are actually heat damaged'. I can easily distinguish between corked and cooked, and I still will tell you that 5-8% of the wines I try are corked. Then add the cooked and premoxed btls, and the bad bottles can easily exceed 10%. And I think most people are not confused between the two.
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Re: Less than 1% of wines corked?

Post #15  Postby Tom Hudson » August 28th 2009, 1:06pm

Chuck - thanks for the feedback.

For clarity purposes, I define "corked" as the moldy, musty smell that we all know. I'm not including bottle variation in my stats of 1.5% rate. Perhaps I should?

Chuck Miller wrote:
Tom Hudson wrote:At my 76 seat restaurant/wine bar, 75%+ of the wine we sell is BTG.

Our corked rate is about 1.5% of those with corks. Our bottles with corks are down to less than 75% now, with screw caps, vino locks, etc. constantly increasing.

IMHO, many of the wines identified as corked are actually heat damaged. Yes, the wines are flawed, but not by the cork.

Since I'm very anal about storage/shipping conditions, we only purchase from the minute portion of importers/distributors who guarantee tempurature control throughout the shipping process.

This is why I believe our failure rate for returned bottles is less.


Tom, no doubt that your purchasing thru importers/distributors that temp control will result in fewer cooked bottles and therefore a lower return rate. But I take exception to your opinion that 'many of the wines identified as corked are actually heat damaged'. I can easily distinguish between corked and cooked, and I still will tell you that 5-8% of the wines I try are corked. Then add the cooked and premoxed btls, and the bad bottles can easily exceed 10%. And I think most people are not confused between the two.
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Re: Less than 1% of wines corked?

Post #16  Postby John Gilman » September 23rd 2009, 6:45am

Interesting dialogue here- I had a question for those in tasting rooms, restaurants and private consumers citing their experience with rates of TCA-tainted wines: Is there any notable variation of TCA taint based on the age of the wine being tasted in the sampling? For most peoples' posts, I do not see any mention of what is being tasted and how old the wines are that are part of the sample for which they are reporting their estimated percentages of tainted wines from cork. Some of the numbers being reported are very much in line with what I used to see a decade ago, when very clearly the cork industry had done little to address the situation of TCA taint and numbers were generally reported in the 5-8% range by many commentators.

But it is very clear to me from reviewing the literature and recently visiting Portugal that giant strides have been made in the last decade and the incidence of TCA taint is dropping dramatically today and is likely to get below the 1% threshold on a consistent basis in the coming years. Now this number includes all types of corks, and ironically, some of the lower level corks are better than the top of the line for avoiding TCA contamination, and if I were a winemaker I would be looking at aglo-corks for my own closures, rather than the top of the line, single punch long corks, as the manufacturing process for the aglos allows for much more certain TCA control than the single piece long corks. If you are a winemaker and running high numbers of TCA contamination during your pre-bottling runs, the question has to be asked what kind of corks are you using and why have you selected this type?

Most wineries that select the top of the line, single punch corks (which ironically run a higher percentage these days of TCA contamination than aglos) due so for aesthetic reasons, as the long, clean and well-grained cork adds a certain luster to the experience of pulling the cork for consumers and sends the message that the winery is committed to excellence in every aspect of the wine producing process. Of course a long, single punch cork also is impossible to inspect or treat for potential TCA contamination on the interior of the cork, so by definition it is a crap shoot what is going on below the surface of a single punch cork. With aglos, the ground up pieces of cork are treated and analyzed prior to being pressed into shape and glued, so the incidence of TCA in these corks is negligible, though the stigma of using a "pressed cork" with consumers cannot be discounted at the present time. I saw a very interesting cork design selected by one winery which was a "twin top" (an aglo cork wtih two slices of solid cork at each end) that had a lovely print design in the middle area of the cork that effectively hid the pressed cork section under the pattern and gave the appearence of being a single punch cork. A brilliant idea and their corks are likely to be virtually TCA free!

As a wine writer I open a lot of bottles, and my incidence for TCA tainted wines is way down over the last several years for young vintages that I am sampling. I do not bother anymore to keep a log, but it has dropped dramatically from a decade ago, when 5% would have been a good number. I still see about 5% with older bottles that I open, and as I write a lot about mature wines, I still share the agony of a corked bottle of potentially great wine ruined by TCA. My own personal threshold for TCA taint is on the higher side, so I am not as sensitive to it as others, which was helpful a few weeks ago when a bottle of 1921 Chateau Montrose was declared mildly corked by two fellow tasters, but the rest of us at the table could not detect any TCA and happily drank the bottle!

The cork industry certainly deserved its vilification for its slipshod methods at quality control in the past, when little if anything was done to address the issues of TCA taint. However, a sluggish and disinterested past must be separated from the very real, aggressive and impressively successful steps that have been taken in the last decade in terms of research and quality control to address the TCA issue and to the best of their ability reduce TCA taint in corks down to a statistically much less significant number- they are not where they want to be yet, but from what I have seen and read, they are moving briskly in the right direction and have made profound progress in the last decade or so. Today I am much more concerned with the issue of wines ruined by permanent reduction under screwcaps than I am with TCA, as my incidence with wines ruined in this manner runs dramatically higher than TCA-tainted young wines, and I am sampling wines under screwcap in their infancy, when most issues of reduction are only in the most formative stages. From the data I have seen on reduction and screwcaps, my numbers would be really ugly if I was sampling SC wines at ages four or five, instead of wines removed from bottling by only 6-12 months.

Just a little food for thought.

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Re: Less than 1% of wines corked?

Post #17  Postby M. Smith » September 23rd 2009, 8:08am

Posted by John Gilman:
Today I am much more concerned with the issue of wines ruined by permanent reduction under screwcaps than I am with TCA, as my incidence with wines ruined in this manner runs dramatically higher than TCA-tainted young wines, and I am sampling wines under screwcap in their infancy, when most issues of reduction are only in the most formative stages.


John, Thank you for these insights. As you probably know, Paul White has expressed related concerns about screw capped- wine (http://www.winewriting.com/Screwcaps.htm). He also disclosed that some attempt to counter reductive wines by adding excess copper salts. For we amateurs, have you encountered any (many?) wines that tasted like they had had such a treatment? Just curious.

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Re: Less than 1% of wines corked?

Post #18  Postby cganzer » September 23rd 2009, 8:17am

I open about an equal mix of young and old wines, and I find that for older wines, I run at about 5% (not counting wines where there's a systemic problem, like the entire case of Mondavi '76 that went down the drain). For younger wines, say 2004 and newer, I honestly can't remember the last time I found one that was corked. I don't know if that's because of better production methods, or that I'm less sensitive than some and it takes the TCA blooming in the bottle for a long time to reach my threshold of sensitivity.
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Re: Less than 1% of wines corked?

Post #19  Postby larry schaffer » September 23rd 2009, 9:53am

John,

Interesting info. I guess my question re: screw caps and reduction - is this something you see immediately after opening and continuing in the wine after it's been open awhile or just at opening? C urious to hear ;. . .

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Re: Less than 1% of wines corked?

Post #20  Postby John Gilman » September 23rd 2009, 6:08pm

Hi Mitch,

I have read quite a bit of what Paul White has written on the issue and he was very instrumental in pointing me in the direction of the research that has been done by the Australian Wine Research Institute and others on issues of reduction and oxidation. I conducted an interview with Dr. White in one of the recent issues of my newsletter, which made for some pretty fascinating reading, and I would be happy to share it with anyone who might be interested in his research (just email me at jbgilman@ix.netcom.com). He has taken a lot of heat in some circles for his willingness to tackle this issue by questioning research and cross checking it with other scientists and the accepted literature in the field of chemistry, and from what I have seen, he has been spot on with all of his critiques.

So I am very aware of the standard operating procedure of adding copper sulphate to wines pre-bottling that has been in affect for several years now in Australia and New Zealand for wines that are destined to be bottled under screwcap. I am uncertain of how these now routine additions of copper sulphate to a wine affect their safety for human consumption (as residual copper is left behind in the wine), as there are no longer any regulations in Australia and New Zealand with respect to setting maximum levels of residual copper, given that the Australian Food Standards Code was changed a few years back abolishing any such maximum level for wine. Previously, the regulations in Australia and New Zealand (both countries operate under the same set of rules for wine) had prohibited residual copper concentrations in excess of 5.0 mg. per liter, which was the same as the maximum level currently allowed in the United States. But within the last few years the governments Down Under have scrapped this maximum level of residual copper in wine- "why" being a very good question to which I have not seen any answer.

The questionable aspect here to my mind is that residual copper cannot be tasted or noticed in a wine unless the level is sufficiently high enough to form a haze by the residual copper's reaction with proteins that might still be in the wine after filtering. Without the "copper haze" formation, there is no way to tell how much residual copper one is consuming when drinking a wine from Australia or New Zealand that has been copper fined, as testing is no longer done for these wines with the abolition of the maximum level for safe human consumption by the good folks responsible for the Australian Food Standards Code. And thanks to GATT, wines produced in one country under regulations that make them safe for their domestic markets are not subject to regulations in the countries that import them, so our FDA maximum limits of 5 mg. per liter of residual copper are not applicable in regards to copper-fined wines from Australasia and are of no use in protecting consumers, just in case there happens to be wines on the market here that are above what is currently deemed safe for human consumption.

In affect, the changes of the Australian Food Standards Code for maximum levels of copper in wine effectively usurped the FDA's ability to police the US market for wines with potentially hazardous levles of residual copper from Australia and New Zealand, assuming of course that the FDA had any interest in doing so. I had contacted a very nice gentleman at the FDA to ask him about this issue, and he was going to look into it and get right back to me. That was six months ago and I have still not heard from him. But to give one some idea of how potentially wide spread the issue is in Australasia today, the Australian Wine Institute published a paper in April of 2008 written by oenologist Geoff Cowey about the issue, entitled "Excessive copper fining of wines sealed under screwcaps- identifying and treating reductive winemaking characters," which was published in The Australian & New Zealand Grapegrower and Winemaker. It makes for some pretty interesting reading, to say the least. I highly recommend reading the paper before opening up the next bottle of Australian or New Zealand wine sealed under screwcap.

The bottom line is that today one does not have to be wary of only of residual copper above safe levels for human consupmption, as in addition, one of the methods now often used to try and remove excess copper prior to bottling is what is called a "Blue Fining", where the wine is fined with potassium ferrocyanide. To quote Mr. Cowey: "However, in most cases (of greater than desired concentrations of copper in the wine), fining with potassium ferrocyanide (PFC), an operation referred to as "blue fining", is required to decrease the concentraton of copper to below the recommended "safe level". (I should note that Mr. Cowey's recommended "safe level" is the 5 mg. per liter that was formally the limit of the Australian Food Standards Code.) The goal of the paper is to give winemakers a firm blueprint for treating wines for potential reduction prior to bottling, so as to minimize the likelihood of excess copper in the wines and the need for blue fining, as Mr. Cowey continues, "over-fining and the retention of excess ferrocyanide in the wine" is not desirable, for "excess ferrocyanide, might, in time, liberate cyanide, thus rendering the wine unsaleable and possibly toxic." Yum.

The bizarre thing is that all of this is done to allow wines sealed under screwcaps to prolong the period of fine drinking before they become liable to permanent reduction- all of the literature that I have read indicates that all of this addition of copper sulphate prior to bottling only pushes further out the onset of reduction in a wine sealed under an anaerobic seal such as screwcaps currently provide- it most emphatically does not prevent it. So the addition of all this heavy metal is to simply give a wider window for the wine to be consumed prior to the onset of reduction- if the wine is sealed under a screwcap. If the wine is sealed under a cork, then none of this- copper sulphate additions, fining with ferrocyanide- are necessary. Additionally, copper fining does not only target the sulfur molecules that are prone to reduction and the formation of thiols in an anaerobic environment, it targets all sulfur compounds in the wine- many of which are resonsible for the aromatic and flavor complexity that makes wine such a compelling beverage in the first place. The literature that I have seen on this issue is very persuasive. So in the end we add all this copper (or strip it out at the risk of adding cyanide), so that we can make the wine less complex from the start, and only push back the day of reckoning with permanent reduction, all so that we can use a specific type of closure! The whole thing is asinine in my opinion.

I should note that the screwcap industry is feverishly working to create better seals that allow a certain degree of oxygen ingress (trying to emulate natural cork's performance in this respect), so that in the future all of this copper fining may no longer be necessary. I would be very curious to hear what winemakers here in the US or Europe are doing to address the potential impact of permanent reduction in wines sealed under screwcaps, as of course they are subject to the limitations on residual copper in wines as set out by the appropriate regulatory agencies in their home countries. But in the interim, I am a bit hesitant to not spit out that screwcapped wine from Australasia from the current vintage that I might be sampling, and needless to say, there are none of those potentially heavy metal wines in my cellar. I would love to see some research done on the safe levels of residual copper in wine for those of us that taste and spit the wines :-)

Best,

John
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Re: Less than 1% of wines corked?

Post #21  Postby John Gilman » September 23rd 2009, 7:22pm

Hi Larry,

Did not mean to ignore your question, but the answer to Mitch was already too long for one post. When I taste screwcapped samples, I routinely decant them for up to an hour to allow some aspects of the reduction elements to blow off, if there are any present in the aromatics of flavors. Since I am generally tasting new releases sealed under screwcap, this element of reduction is not usually a major factor when I am tasting the wines, as they are often close enough to their bottling to not have been dramatically affected at this point. When I do hit one that is getting a tad "stinky", I will decant it and eventually add a penny that still has some copper in the composition to clean the wine up in the glass, which it generally does briskly (adding my own heavy metal instead of letting the winemaker do it- very hands on of me).

IME, I find a lot more wines that are affected by early reduction under screwcap showing this issue on the palate, by generating a sense of "metallic minerality" (for lack of a better term), pinched fruit impressions on the palate, and generally very short finishes. As the statistics I have seen for most wines sealed under screwcap are that they are often consumed within 18 months of bottling, I suspect that this is a much more frequent reductive characteristic encountered by casual wine drinkers, rather than the more advanced aromatic elements of rotting cabage, burnt rubber or struck matchstick that in my experience tend to show up a bit later on in the cycle. I have never kept any log on these wines to try and quantify my experiences, so this is simply anedoctal, and I do not have a single bottle in my personal cellar that is sealed under screwcap, so I cannot comment at all on how reduction trends over many years of bottle age for these wines.

I should note that I have absolutely no beef with screwcaps as a wine closure as they were presented to the trade at the outset- though even at that time I always wondered about their applicability for wines meant for long-term cellaring, which happen to be the vast, vast majority of wines in my own personal cellar. But where I take exception with is how the screwcap industry and its proponents have reacted to the issue of reduction, which no one anticipated (as far as I know) when the closures first began to be adopted in large numbers, but which has been pretty seriously documented for the last four or five years. IMO, denial, slipshod science and character assisination seems to have been the most often utilized responses-on the surface- for proponents of screwcaps to the issue of reduction (not always from people with overt ties to the manufacturers mind you, but often wine people who had staked their reputations on what they had been told out of the blocks about this closure and did not see any way to extricate themselves without dramatic reversals of position, or this is at least how it seemed to me).

The steps described in the previous post certainly seem to be the responses behind the scenes that were advocated. While I fully understand the potential liability issues involved here, in my opinion the industry response has still been pretty ethically dubious- at least when it comes to the addition of copper and potentially cyanide to the wine. One can easily imagine a much more proactive response that could have minimized the potential damage of several follow-on vintages, once the research became clear about tendency to permanent reduction of wines sealed under completely anaerobic conditions, but it is my distinct impression that misdirection, mud-slinging and highly questionable "wine preparation techniques pre-bottling" were the industry's general response to the issue of problematic wine evolution under screwcap. So on that level I am certainly not impressed by the vocal proponents of the closure.

Of course all of this discussion is predicated on how screwcaps currently perform as a wine closure, and I have already seen some evidence that the industry is making dramatic headway with creating closures that allow a certain amount of oxygen ingress, which if successful should solve the issue of potential reduction. This is of course good news, but does this absolve them of what in to my mind is their failure to forthrightly address the issue of reduction in the first place when the evidence first began to pile up? In my opinion the track record to date has been less than exemplary on this score, and I do not see a whole lot of incentive (except of coure money, as screwcaps are decidedly cheaper than corks) on the part of winemakers to continue to champion this closure system and its industry, when it has been my impression that they have been a little slow to fess up in the first place. But I am just a lowly wine writer, and there may well be issues in this equation that I am completely unaware of and would be delighted to learn more about. For it seems to me that on this issue, the more transparency and dialogue that are involved, the more likely it is that we will not end up ill from heavy metals or something worse in the wines. In this respect, the FDA's complete inattention and continuing lack of overt action has been one of the most egregious part of the entire episode, which certainly on the surface looks to be protection of the industry at the expense of potential adverse health affects on the consumer- in my opinion of course.

Best Regards,

John
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Re: Less than 1% of wines corked?

Post #22  Postby larry schaffer » September 24th 2009, 12:56am

John,

Thanks for the detailed reply to my question!

Your points are very interesting ones, and ones that I do not tend to hear very often. The landmark AWRI study which started the discussion of reductive issues with screw capped wines is one I am familiar with, and one that can be interpreted in a few different ways. From what I understand, the wine used for the study was 'problematic' from the get go, showing signs of mercaptans prior to bottling for the study . . . not good.

Your comments stand out to me because I continue NOT to hear about systemic reduction issues with screw cap wines. Just to be as wide open as possible, I only use screw caps for my own brand, tercero wines, but use all types of clsoures for Fess Parker Winery and Epiphany Cellars, my employer. I have no real 'beef' with corks - other than when are 'bad' . . .

Looking forward to contiuing these discussions!

Cheers!
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Re: Less than 1% of wines corked?

Post #23  Postby John Gilman » September 24th 2009, 3:46pm

Hi Larry,

As I noted above, the incidence of reduction with wines sealed under screwcaps has been pretty well established at this point, though to my knowledge, many of the very earliest claims that disputed the likelihood of reduction have continued to be recirculated by proponents of using scewcaps for wine closures. I do not have all of my data handy here and have not boned up on it in the last several months, so I am really not up to speed to cite the specific papers and studies. From what I can tell, AWRI has moved pretty energetically in the last year or two to bring in some new people in to guide their research in this area and are now producing some impressive science, but IMO there are clearly some holes in the post-bottling chemistry that their research relied upon six or seven years ago, when Peter Godden was one of their chief architects of research in this field. The AWRI study that you may be referring to may date back to Mr. Godden's tenure and his non-existent theory of sulfide equilibria that was the cornerstone of his analysis of post-bottling reduction issues for wines sealed in an anaerobic manner. A great article to take a look at was Dr. Paul White's response to AWRI's published objections to his piece in Harper's, entitled Scientifically Speaking- this intercourse dates back to 2006 and 2007. The response from Dr. White can be found at:

http://www.harpers.co.uk/misc/content/a ... -awri.html

and from here one can easily work back to the scientific papers published about this issue. Dr. White's piece here is pretty in-depth and makes very interesting reading.

I would be very inerested to hear how you prepare your wines pre-bottling for closure under screwcap, and if they are treated differently than the wines that you seal under natural cork. As I noted above, I have not cellared any screwcapped wines in my own cellar for long-term following, and hence am always interested to hear other people's experience with screwcapped wines over extended cellaring. And I am fully in accord with you in the frustration with hitting TCA-tainted wines- my only fear is that their replacement may be causing more damage in percentage terms than the old TCA numbers. And from the research that I have seen, the old TCA numbers for natural cork are not reflective of the dramatically improved situation today.

All the best,

John
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Re: Less than 1% of wines corked?

Post #24  Postby M. Smith » September 25th 2009, 6:15am

Posted by John Gilman:
I [John Gilman] conducted an interview with Dr. White in one of the recent issues of my newsletter, which made for some pretty fascinating reading, and I would be happy to share it with anyone who might be interested in his research (just email me at jbgilman@ix.netcom.com).


For anyone even casually interested in the 'state-of-the art' issues behind screw cap-enhanced "reductive wine" problems, take advantage of John Gilman's generous offer to share this recent interview of Paul White with us.
[thankyou.gif]

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Re: Less than 1% of wines corked?

Post #25  Postby Paul Starr » September 27th 2009, 10:43pm

John Gilman wrote:Hi Larry,

As I noted above, the incidence of reduction with wines sealed under screwcaps has been pretty well established at this point, though to my knowledge, many of the very earliest claims that disputed the likelihood of reduction have continued to be recirculated by proponents of using scewcaps for wine closures. I do not have all of my data handy here and have not boned up on it in the last several months, so I am really not up to speed to cite the specific papers and studies. From what I can tell, AWRI has moved pretty energetically in the last year or two to bring in some new people in to guide their research in this area and are now producing some impressive science, but IMO there are clearly some holes in the post-bottling chemistry that their research relied upon six or seven years ago, when Peter Godden was one of their chief architects of research in this field. The AWRI study that you may be referring to may date back to Mr. Godden's tenure and his non-existent theory of sulfide equilibria that was the cornerstone of his analysis of post-bottling reduction issues for wines sealed in an anaerobic manner. A great article to take a look at was Dr. Paul White's response to AWRI's published objections to his piece in Harper's, entitled Scientifically Speaking- this intercourse dates back to 2006 and 2007. The response from Dr. White can be found at:

http://www.harpers.co.uk/misc/content/a ... -awri.html

and from here one can easily work back to the scientific papers published about this issue. Dr. White's piece here is pretty in-depth and makes very interesting reading.

I would be very inerested to hear how you prepare your wines pre-bottling for closure under screwcap, and if they are treated differently than the wines that you seal under natural cork. As I noted above, I have not cellared any screwcapped wines in my own cellar for long-term following, and hence am always interested to hear other people's experience with screwcapped wines over extended cellaring. And I am fully in accord with you in the frustration with hitting TCA-tainted wines- my only fear is that their replacement may be causing more damage in percentage terms than the old TCA numbers. And from the research that I have seen, the old TCA numbers for natural cork are not reflective of the dramatically improved situation today.

All the best,

John


I'd also suggest having a look at AWRI's response to Paul White at:
http://www.harpers.co.uk/misc/content/a ... -2005.html

There is a lot of firsthand experience in Australia of beautiful, graceful, aging curves for wines under screwcap. Reduction is hardly an inevitable result from using a screwcap. Especially for whites such as riesling and semillon, I am not prepared to cellar under cork any more.

FWIW, I have had more reduced wines under cork than screwcap.
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Re: Less than 1% of wines corked?

Post #26  Postby M. Smith » September 28th 2009, 5:39am

A question for Paul Starr -- If you happen to know why "the joint Australia and New Zealand Food Safety
Authority quietly eliminated any standards for residual copper," many concerned readers here might appreciate your interpretation about this perplexing turn of events. Thanking you in advance.

Paul White quote from John Gilman's aforementioned interview:
It staggers the imagination that the joint Australia and New Zealand Food Safety
Authority quietly eliminated any standards for residual copper last August in light of
other wine industries tightening theirs up at the same time. Now why would they do that?

With testing- now (conveniently?) suspended, it’s impossible to know precisely how
many screw capped Australasian wines currently exceed globally accepted safety limits.
That couldn’t have anything to do with it could it?

More worrying, a recent paper in Australian & NZ Grapegrower & Winemaker
(April 2008, pp 49-56) reports the AWRI observing a “dramatic increase in the addition
of coppering immediately prior to bottling” specifically employed as a preventative for
sulphide reduction under screw caps. During the last three years the AWRI have
encountered a 30 fold increase in excessively coppered wines submitted for “blue fining”
trials. This complex treatment employs potassium ferrocyanide to reduce excess copper
levels, which then requires bottling with extra iron to reduce the risk of residual cyanide-
another toxin- post bottling. Now THAT is a very scary thing.


Subsequent edits:

1. For those wishing to read "Scientifically speaking," see:
http://www.realcork.org/artigo.php?art=69
and click on the text discussing:
Scientifically speaking
Paul White gets into the technical nitty-gritty to reveal the shortcomings both of screwcaps and of the theories seeming to support their use
.

2. FWIW, If I am not mistaken, the AWRI respondent to Paul White's "Scientifically Speaking" article in Harpers appears to be a highly trained microbiologist ? (http://www.whoswhosa.co.za/Pages/profil ... IndID=1620), i.e., perhaps not a dyed-in-the-wool chemist.

The Australian Wine Research Institute refutes Paul White's 'Scientifically Speaking' feature in Harpers' Closures supplement in December 2005
http://www.harpers.co.uk/misc/content/a ... -2005.html

Thursday, 31 August 2006
Professor Sakkie Pretorius says: In this letter I do not intend to enter into a detailed critical review of the article. Rather, this response addresses passages from the article that are factually incorrect, or which use incomplete AWRI data which, used in that way, are misleading, or which misrepresent the AWRI?s position on various issues. Additionally, some areas that we regard as scientifically unsound for an article that purports to be a review of the science of wine closures are also addressed.


3. For those of you interested in reading a another Harpers article by Paul White, see ‘The tail wags the dog’, Harpers, December 2006" at: http://www.corkfacts.com/contpges/archmaine.htm

Yiamos !
Mitch

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Re: Less than 1% of wines corked?

Post #27  Postby Paul Starr » September 28th 2009, 6:42pm

I have been unable to find any verification of Mr Gilman's claims that in August last year FSANZ "quietly eliminated any standards for residual copper".

In 2007, there was discussion of setting a maximum copper requirement within our food standards beyond the current "good manufacturing practice" standards approach. This came up in consultation about recognising cupric citrate without it being on a bentonite base. FSANZ did not consider there were sufficient health or other reasons to do so.

However, the revised agreement on wine between Australia and the EU signed in Dec 2008 reiterated permissable:
"use of copper sulphate to eliminate defects of taste or smell in the wine, up to a maximum of 1 gram per hectolitre, provided that the copper content of the wine so treated does not exceed 1 milligram per litre"

My personal preference is to not use copper adds - get the wine right for bottling in the first place - but I don't think things are quite as they are being made out by Mr Gilman and Mr White. 1 milligram a litre or less is pretty low for something that can also come in via vineyard copper sprays (no mention of these as an Old World practice), is an essential element in the human diet (deficient in many over-purified Western foods), where the WHO per person safe levels guidance is 20 micrograms per kilo per day.
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Re: Less than 1% of wines corked?

Post #28  Postby Paul Starr » September 28th 2009, 7:10pm

Looking further, there was a 1999 ANZFA (forerunner of FSANZ) review of metals and contaminants in food. In that review:
- wine was not identified as a food that makes a major contribution to the dietary intake of copper for Australia or New Zealand consumers
- the maximum level for copper in a range of foods was deleted from the Code due to the low public health and safety risk of copper in foods.

This was nothing specific to wine, but a general finding that there was no convincing case to set maximum levels of copper for foods in the Code.

It's not quite quietly in August last year, but is perhaps the source being referred to.

I'd be more concerned about offal and macrobiotic diets...
"Most foods in Australia and New Zealand contain between 1–5 mg/kg with the highest levels found in liver (up to 237 mg/kg) and more intermediate levels (8–24 mg/kg) found in nuts, seeds, bran and oysters. "
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Re: Less than 1% of wines corked?

Post #29  Postby Peter Petersen » September 28th 2009, 7:18pm

For the first half of the year I ran 1:7 corked wines. That's really bad. Then again I've had amazing runs wine only 1:100 being corked, but that's the best I've ever achieved.
If the corks were actually tested I'm sure it'd look worse as I'm sure many underperforming wines are mildly corked.
Maybe I can ask this here, since ebob considered it inappropriate for wine talk, is there an easy test for TCA that I can do at home? Everything I look for is either quite expensive or if cheap simply testing for chlorine.
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Re: Less than 1% of wines corked?

Post #30  Postby M. Smith » September 29th 2009, 7:57am

Paul, Thank you for taking the time to share this information.
Paul Starr wrote:I have been unable to find any verification of Mr Gilman's claims that in August last year FSANZ "quietly eliminated any standards for residual copper".

In 2007, there was discussion of setting a maximum copper requirement within our food standards beyond the current "good manufacturing practice" standards approach. This came up in consultation about recognising cupric citrate without it being on a bentonite base. FSANZ did not consider there were sufficient health or other reasons to do so.

However, the revised agreement on wine between Australia and the EU signed in Dec 2008 reiterated permissable:
"use of copper sulphate to eliminate defects of taste or smell in the wine, up to a maximum of 1 gram per hectolitre, provided that the copper content of the wine so treated does not exceed 1 milligram per litre"

My personal preference is to not use copper adds - get the wine right for bottling in the first place - but I don't think things are quite as they are being made out by Mr Gilman and Mr White. 1 milligram a litre or less is pretty low for something that can also come in via vineyard copper sprays (no mention of these as an Old World practice), is an essential element in the human diet (deficient in many over-purified Western foods), where the WHO per person safe levels guidance is 20 micrograms per kilo per day.

A brief search of FSANZ disclosed the following document:
http://www.foodstandards.gov.au/_srcfil ... %20wine%22

within which I note the following passage:
10. Consultation

10.1 Public Consultation at Initial and Draft Assessments

The Initial Assessment was advertised for public comment between 4 October 2006 and
15 November 2006. Eight submissions were received during this period.

The Draft Assessment Report was advertised for public comment from 21 March 2007 to 2
May 2007. Four submissions were received during this period, with one late submission
received after the closing date for public comment. All submitters supported the Application,
noting that there are no public health and safety concerns associated with the use of copper
citrate under the proposed conditions of use and that the potential benefits for consumers and
industry outweigh any costs.

At Attachment 4 is a summary of the submissions received during the first and second round
of public comment. FSANZ has taken the submitters’ comments into account in preparing
the Final Assessment of this Application. While the comments received after the closing date
cannot be considered and taken into account as a submission on the Draft Assessment of this
Application, they have been considered in this report as ‘other relevant material’ under the
Food Standards Australia New Zealand Act 1991. The major issues raised at Initial and Draft
Assessments are discussed below.

10.1.1 Copper Residue Limit

At Initial Assessment, several submitters indicated that a maximum limit (ML) for copper in
wine should be established in conjunction with this Application. This issue was again raised
at Draft Assessment by one submitter who noted the following concerns:

• Data has not been provided to support the claim that addition of cupric citrate to wine
without a bentonite base will not lead to undesirably high copper residues/compounds
in wine or will not promote the production of undesirable side products in the wine (e.g.
reactions with thiol compounds).

• It will be difficult to determine whether copper citrate is being added to wine to improve
the quality of raw materials or to mask poor manufacturing practices. Therefore, a
maximum copper limit should be set at 0.3 mg/L, in line with the Applicant’s comment
that haze begins to form in wine at concentrations greater than this.


• The Applicant contends that overuse of copper citrate will be self-regulated through the
formation of reddish brown hazes and precipitates in wine. However, in red wines it
will be problematic for consumers to detect these formations prior to purchase.


10.1.1.1 FSANZ’s Response

The key principle when considering establishment of an ML for a substance in food (e.g.
food additive, processing aid or a contaminant) is whether that substance presents a
significant risk to public health and safety and makes a significant contribution to total
dietary exposure of that substance. In addition, the levels used in food should only be used in
an amount necessary to achieve the desired technological need.

FSANZ acknowledges that it has been unable to obtain data from Australian or international
winemakers or from the literature, on the likely concentration of copper dissolved in wine
following treatment with cupric citrate. Therefore, the safety assessment for this Application
focussed on the function of cupric citrate as a processing aid in removing hydrogen sulphide
and other sulphur compounds (e.g. simple thiols) from wine, in comparison with other
permitted copper-based processing aids in the Code, namely, cupric sulphate and cupric
citrate on a bentonite base.
These processing aids are permitted to be added at GMP levels.

The Safety Assessment Report (Attachment 2) concluded that the use of cupric citrate at
GMP levels as a processing aid in wine does not pose a risk to public health or safety. The
residue levels of copper in the final wine product are expected to be low and similar to
residues produced using other permitted copper-based processing aids which are currently
permitted at GMP levels. Furthermore, the review of metals and contaminants in food
(Proposal P157) did not identify wine as being a major contributor to the dietary intake of
copper for Australian and New Zealand consumers. For these reasons, this Application does
not raise any public health and safety concerns.

In the absence of an established ML for copper residues in wine in conjunction with this
Application, it is acknowledged that there is scope for the manufacturer to add copper citrate
at a level greater than that required to achieve the required technological function. This
argument can also be made for copper sulphate and copper citrate on a bentonite base which
do not have maximum copper limits established in the Code and are currently approved at
GMP. However, FSANZ notes that the application rate of copper citrate to wine is self-
limiting due to the formation of haze and ultimately, precipitates, in the event that excess
copper citrate is added.
While a haze may not be visible in red wines, it is expected that any
resulting precipitate would be apparent in both red and white wines, and should therefore
discourage excess use. It should also be noted that excess copper citrate in wine can be
removed from solution by the use of potassium ferrocyanide as discussed below. For these
reasons, FSANZ considers that it is not necessary to establish an ML for copper in wine in
conjunction with this Application.


10.1.2 Removal of Excess Copper Citrate

At Draft Assessment, one submitter commented that the mechanisms by which excess copper
citrate in wine will be removed from solution have not been identified, noting that the major
advantage of binding copper sulphate and copper citrate to a bentonite base was the ease of
removal from solution.

10.1.2.1 FSANZ’s Response

As outlined in the Food Technology Report at Attachment 3, excess copper in solution is
removed by the use of blue finings (potassium ferrocyanide), which produces an insoluble
precipitant of Fe(CN)6Cu2 and is removed from the wine by filtration. This process is also
used to remove excess copper in solution from wine where copper sulphate is used as a
processing aid.

Potassium ferrocyanide is an approved processing aid in the Table to clause 6 in Standard
1.3.3 and in the Table to clause 4 in Standard 4.5.1. It should also be pointed out that copper
sulphate is not used bound to a bentonite base when it is used to treat wine.

10.1.3 Trade Restrictions

The Food Technology Association of Victoria raised the question of whether the proposed
amendment would lead to trade restrictions.

10.1.3.1 FSANZ’s Response

The proposed amendment seeks to expand permissions. It does not seek to delete any
currently existing permission, in that copper citrate on a bentonite base would be
encompassed by the general permission for copper citrate, and thus trade would not be
affected. However, it should also be noted, copper citrate per se is not listed as an approved
processing aid in the current Australia EC Wine Agreement (although the updated agreement
which includes copper citrate was initialled on 6 June 2007), therefore Australian and New
Zealand wine manufacturers producing wine for export to Europe would not be able to use it.

Copper residues in wine resulting from the use of different forms of copper citrate i.e.
compared to copper sulphate or copper citrate on a bentonite base, are unlikely to be
different. The current Australia EC Wine Agreement specifies a 1 mg/L maximum residue of
copper in the final product, which is also the limit for wine imported into Europe.

10.1.4 Removal of Permission for Copper Citrate on a Bentonite Base

At Draft Assessment, one submitter questioned the removal of the permission for copper
citrate bound to a bentonite base and suggested that the drafting be re-worded to indicate that
permissions include copper citrate on a bentonite base.

10.1.4.1 FSANZ’s Response

As discussed in the previous response, the existing permission for copper citrate on a
bentonite base would be encompassed by the general permission for copper citrate. Both
copper citrate and bentonite will be permitted processing aids. FSANZ does not consider that
this needs to be clarified in the drafting.



Hmmm......

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Re: Less than 1% of wines corked?

Post #31  Postby M. Smith » September 30th 2009, 7:21am

This little ditty popped up recently:
http://www.bkwine.com/bkwine_brief/brief-065-e.htm

The EU and Australia recently signed a new trade agreement. One part of that agreement says that Australia will no longer use the denominations Port, Sherry and Marsala for its fortified wines. Many Australian wines have been called such things, since these kind of naming restrictions simply are governed by international agreements, and no such limitation had previously been agreed. (Do you remember the Danish feta cheese?) The wine producers in Australia say that this will cost them millions of dollars since they will have to change their naming and establish new brand identities. The agreement also covers e.g. Moselle, Burgundy, Sauterne, and Chablis. In return the Europeans will recognize the Australian wine regions as specific denominations (Coonawarra, South Australia etc) and will allow certain wine making techniques regularly used in Australia but not permitted in Europe to be used for Australian wines imported to Europe (e.g. use of oak chips and copper citrate). Read more: http://www.abc.net.au and http://www.theaustralian.news.com.au

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Re: Less than 1% of wines corked?

Post #32  Postby John Gilman » October 1st 2009, 9:14am

Maybe the winemakers or chemists here can chime in, as I was wondering what are the primary differences to the finished wine when deciding between utilizing copper citrate and copper sulphate to prepare wines for bottling, as the FSANZ seems to have fairly recentyly allowed copper citrate to be used as a processing agent in winemaking, if I read this paper correctly. Is copper citrate considered preferable to copper sulphate for countering a wine's propensity towards reduction prior to bottling? Would either of these processing agents be necessary if the wine in question were to be sealed under natural cork- assuming that the wine was not problematic in terms of potential reductive qualities ahead of time.

Best,

John
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Re: Less than 1% of wines corked?

Post #33  Postby Paul Starr » October 1st 2009, 8:09pm

M. Smith wrote:This little ditty popped up recently:
http://www.bkwine.com/bkwine_brief/brief-065-e.htm

The EU and Australia recently signed a new trade agreement. One part of that agreement says that Australia will no longer use the denominations Port, Sherry and Marsala for its fortified wines. Many Australian wines have been called such things, since these kind of naming restrictions simply are governed by international agreements, and no such limitation had previously been agreed. (Do you remember the Danish feta cheese?) The wine producers in Australia say that this will cost them millions of dollars since they will have to change their naming and establish new brand identities. The agreement also covers e.g. Moselle, Burgundy, Sauterne, and Chablis. In return the Europeans will recognize the Australian wine regions as specific denominations (Coonawarra, South Australia etc) and will allow certain wine making techniques regularly used in Australia but not permitted in Europe to be used for Australian wines imported to Europe (e.g. use of oak chips and copper citrate). Read more: http://www.abc.net.au and http://www.theaustralian.news.com.au


I don't quite get your point with these quotes, but this was announced at the beginning of December 2008. It's caused some serious issues for the fortified wine producers, especially those making Australian muscat and tokay.

Anyway, as I understand it, cupric citrate was already able to be used if on a bentonite base. the revisions were there really to amend the technicality that the same thing without bentonite wasn't allowed.

On the broader issues of whether there was a quiet change last August that deleted the limits on the use and residuals of copper in Australian wine, and that this was somehow in cahoots with the use of screwcaps, which are also the reductive doom of wine, I have done checking:
1. there was no change last August
2. there was a change in 1999 to our food code to remove a whole bunch of prescriptions where they pertained to things that were not hazardous to human health and safety in the concentrations consumed in the Australian diet
3. in those 1999 removals of prescriptions that lacked evidence of likely hazard, one of the removals was of the maximum limit for copper in wine
4. none of that had anything to do with use of closures in winemaking
5. key Australian export markets still set limits on use and residues of copper
6. some of those markets, or segments within those markets (eg UK supermarket clients) still require test evidence of compliance with limits, including copper limits
7. AWRI still tests for copper when that is required by the export market and client, though there is no default, mandatory testing for copper residues for all product intended for export.

This kind of fact-checking is important, and not that hard. It only took me a few hours scattered over a few days to speak directly to AWRI, go through Australian Wine and Brandy Corporation export requirements, and sift through the history of food standards amendments in the ANZFA and FSANZ days, including the 1999 code revisions.

None of this is to excuse lazy winemaking that uses copper when reduction is not present or a real risk, or overdoing additions and then having hazes or to do further corrections. To me, that is clearly an area that needs improvement (as AWRI also note). However, there is no evidence to support Mr Gilman's conclusions of some kind of collusion between the supposed soulless technocracy of Australian wine and our food standards bodies.

The way this is currently being phrased comes across as bigotry and lazy writing (why do research when I have my prejudice to guide me?). Instead of hinting at collusion and conspiracy, why not spend more time getting information from people like John Vickery who have decades of first-hand experience with trials of screwcap use, winemaking for screwcap closures, and the aging pathways of Australian wines under screwcaps (including for riesling)?
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Re: Less than 1% of wines corked?

Post #34  Postby M. Smith » October 2nd 2009, 7:55am

Post by Paul Starr:
I don't quite get your point with these quotes, but this was announced at the beginning of December 2008. It's caused some serious issues for the fortified wine producers, especially those making Australian muscat and tokay.

Anyway, as I understand it, cupric citrate was already able to be used if on a bentonite base. the revisions were there really to amend the technicality that the same thing without bentonite wasn't allowed.

On the broader issues of whether there was a quiet change last August that deleted the limits on the use and residuals of copper in Australian wine, and that this was somehow in cahoots with the use of screwcaps, which are also the reductive doom of wine, I have done checking:
1. there was no change last August
2. there was a change in 1999 to our food code to remove a whole bunch of prescriptions where they pertained to things that were not hazardous to human health and safety in the concentrations consumed in the Australian diet
3. in those 1999 removals of prescriptions that lacked evidence of likely hazard, one of the removals was of the maximum limit for copper in wine
4. none of that had anything to do with use of closures in winemaking
5. key Australian export markets still set limits on use and residues of copper
6. some of those markets, or segments within those markets (eg UK supermarket clients) still require test evidence of compliance with limits, including copper limits
7. AWRI still tests for copper when that is required by the export market and client, though there is no default, mandatory testing for copper residues for all product intended for export.

This kind of fact-checking is important, and not that hard. It only took me a few hours scattered over a few days to speak directly to AWRI, go through Australian Wine and Brandy Corporation export requirements, and sift through the history of food standards amendments in the ANZFA and FSANZ days, including the 1999 code revisions.

None of this is to excuse lazy winemaking that uses copper when reduction is not present or a real risk, or overdoing additions and then having hazes or to do further corrections. To me, that is clearly an area that needs improvement (as AWRI also note). However, there is no evidence to support Mr Gilman's conclusions of some kind of collusion between the supposed soulless technocracy of Australian wine and our food standards bodies.

The way this is currently being phrased comes across as bigotry and lazy writing (why do research when I have my prejudice to guide me?). Instead of hinting at collusion and conspiracy, why not spend more time getting information from people like John Vickery who have decades of first-hand experience with trials of screwcap use, winemaking for screwcap closures, and the aging pathways of Australian wines under screwcaps (including for riesling)?


“copper wine illness”

http://books.google.com/books?id=J3jPAA ... ss&f=false

“Karsten has stated (J. Soc. Chem. Ind. 1896, 367) that attacks of illness resembling dysentery [diarrhoea?] have been caused by a wine which contained copper in such quantity as to give a visible deposit on steel in 12 hours. Its presence was due to spraying the vines with a copper salt.”

http://books.google.com/books?id=4_HNAA ... ne&f=false

“Copper in Wine H. Karsten (Zeits osterr Apoth Ver, 1896, xxxiv, 84 through Chem Zeit Rep, 1896, 37) – A number of cases of vomiting and diarrhea have recently occurred in Switzerland, which seemed probably due to copper poisoning. A bright steel blade immersed in the suspected wine gave a distinct copper reaction in twelve hours, the metal evidently gaining access to the wine owing to the unripe grapes having been sprayed with a preparation of copper in the vineyards.”


“copper casse”
http://books.google.com/books?id=9En27z ... ne&f=false

“copper tannin wine”

http://cat.inist.fr/?aModele=afficheN&cpsidt=1215865

http://www.sciencedirect.com/science?_o ... f8b5a9e7a3



http://www.foodstandards.gov.au/_srcfil ... %20wine%22

pp 17-18:
In humans there is limited evidence that acute ingestion of copper at very high doses can be toxic, in some cases leading to coma and death. Ingestion of copper at such doses, however, is usually the result of the contamination of beverages (primarily drinking water) or from accidental or deliberate ingestion of large quantities of copper salts. Effects on the gastrointestinal tract, such as nausea, vomiting and diarrhoea, occur at lower copper levels. The doses reported to induce such effects range from 2 to 32 mg/day in drinking water. This contrasts with the fact that up to 13 mg/day can be ingested via food without any apparent adverse effect on human health and suggests that the ionic form of copper may have a bearing on its toxicity.

Cupric citrate is only slightly soluble compared to cupric sulphate. Both compounds will
react with hydrogen sulphide in solution to form insoluble cupric sulphide (CuS) and either citric acid or sulphuric acid (from cupric citrate and cupric sulphate respectively). However, only dissociated ionic salts can undergo reaction in solution. The dissociation of cupric citrate in solution occurs slowly and will be driven by the removal of the free copper ions from solution by reaction with sulphide to form insoluble cupric sulphide. Cupric citrate in excess of what is required to remove sulphur chemicals from solution, being only slightly soluble, can be removed from solution readily. That is, once the sulphur chemicals are removed from solution by the copper ions, any remaining cupric citrate will not dissolve to any great extent. On the other hand, cupric sulphate dissolves easily and provides a greater amount of copper ions available to react with sulphur containing compounds. However a greater amount of copper ions may remain in solution even after sulphur groups have essentially been removed from solution, compared to when cupric citrate is used.

Therefore there is no public health and safety risk from the use of cupric citrate at GMP as a processing aid in wine.

[scratch.gif] [scratch.gif] [scratch.gif]
Paul,

In light of the above website citations, some of us continue to question the final sentence (conclusion) quoted from the FSANZ attachment 2 safety assessment. Of course, winemakers who judiciously follow "GMP" (good manufacturing practices) are considerably less likely to add copper excessively. My concern stems from the nonobvious qualifications within documents like the FSANZ report. The mere fact that the two citations by Karsten do not appear to be found in the FSANZ document noted above gives one considerable pause about the thoroughness of their background research. The two citation hits of the Karsten reports surfaced after a few minutes of surfing for two mornings.

Incidentally, my PhD thesis disclosed the structure of a novel microbial iron chelator. I mention this simply to indicate that my professional training also leads me to question several of the conclusions (inferences, actually) in the FSANZ safety assessment. Some of the website hits listed above demonstrate that tannins can be effective sequestration (chelation) agents for trace transition metals such as copper, iron, etc. So for the report to tacitly imply that many of the copper complexes are largely insoluble effectively overlooks the likelihood that copper speciation in the bottled wine probably includes a portion solubilized by natural metal-binding agents such as tannins.

You seem to be a thoughtful, helpful, and well-intended winemaker. You have earned my respect. But so have John Gilman and Paul White. There's more to this story than meets the casual glance and I continue to admire their quest to obtain scientific explanations for an issue that concerns many winelovers (few of whom are aware of its implications).

Lastly, it is my impression that the non-mandatory? sampling of wines for export and import won't necessarily catch all (or most?) violative products. I believe this may be one crux for the concern expressed by several of us.

Yiamos !
Mitch

To blend Nebbio
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Re: Less than 1% of wines corked?

Post #35  Postby M. Smith » October 2nd 2009, 8:41am

John Gilman wrote:Maybe the winemakers or chemists here can chime in, as I was wondering what are the primary differences to the finished wine when deciding between utilizing copper citrate and copper sulphate to prepare wines for bottling, as the FSANZ seems to have fairly recentyly allowed copper citrate to be used as a processing agent in winemaking, if I read this paper correctly. Is copper citrate considered preferable to copper sulphate for countering a wine's propensity towards reduction prior to bottling? Would either of these processing agents be necessary if the wine in question were to be sealed under natural cork- assuming that the wine was not problematic in terms of potential reductive qualities ahead of time.

Best,

John


John,
According to what little I've read, the recent preference favoring copper citrate (on bentonite?) over copper sulfate in some, but not all, countries may revolve around the alleged insolubility of copper citrate and the complex it is said to form with various sulfides (see the safety assessment attachment in the FSANZ report). I haven't dredged up the scientific literature about this. On the other hand, assertions that many of the salient copper complexes tend to be insoluble probably underestimates the trace levels of copper remaining in solution owing to the presence of natural metal-binding agents such as tannins [edit: other polyphenols, proteins and tartrates]. Interpretations that excessively treated wines are self-regulating endeavors, owing to the visual defects (esp. in white wines), is hardly reassuring.

Edited update:
Colored Haze: The use of copper, zinc, iron, or aluminum implements or primary fermentation vessels can cause white, dark, purplish, or brown hazes. If the culprit was iron or copper, a few drops of citric acid will usually clear the haze.

http://winemaking.jackkeller.net/problems.asp
Last edited by M. Smith on October 6th 2009, 11:07am, edited 3 times in total.

Yiamos !
Mitch

To blend Nebbio

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