Less than 1% of wines corked?

WINE TALK
21

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

22

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!

23

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/article/3922-paul-white-replys-to-the-awri.html" onclick="window.open(this.href);return false;

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

24

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]

25

I’d also suggest having a look at AWRI’s response to Paul White at:
http://www.harpers.co.uk/misc/content/article/3403-the-australian-wine-research-institute-refutes-paul-whites---scientifically-speaking-feature-in-harpers-closures-supplement-in-december-2005.html" onclick="window.open(this.href);return false;

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.

26

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" onclick="window.open(this.href);return false;
    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

.

  1. 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/profilefull.aspx?IndID=1620" onclick="window.open(this.href);return false;), 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/article/3403-the-australian-wine-research-institute-refutes-paul-whites---scientifically-speaking-feature-in-harpers-closures-supplement-in-december-2005.html> " onclick="window.open(this.href);return false;

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.

  1. For those of you interested in reading a another Harpers article by Paul White, see ‘The tail wags the dog’, Harpers, December 2006" at: corkfacts.com - Diese Website steht zum Verkauf! - Informationen zum Thema Wine." onclick="window.open(this.href);return false;
27

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.

28

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. "

29

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.

30

Paul, Thank you for taking the time to share this information.

A brief search of FSANZ disclosed the following document:
http://www.foodstandards.gov.au/_srcfiles/FAR_Final_A562_Copper_Citrate_as_a_PA_in_Wine.pdf#search=“copper%20wine”" onclick="window.open(this.href);return false;

within which I note the following passage:

  1. 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…

31

This little ditty popped up recently:
http://www.bkwine.com/bkwine_brief/brief-065-e.htm" onclick="window.open(this.href);return false;

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> " onclick="window.open(this.href);return false; and > http://www.theaustralian.news.com.au> " onclick="window.open(this.href);return false;

32

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

33

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)?

34

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”

A Dictionary of Applied Chemistry - Thomas Edward Thorpe - Google Books" onclick="window.open(this.href);return 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.”

The Analyst - Google Books" onclick="window.open(this.href);return 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”
Wine Science: Principles, Practice, Perception - Ronald S. Jackson - Google Books" onclick="window.open(this.href);return false;

“copper tannin wine”

http://cat.inist.fr/?aModele=afficheN&cpsidt=1215865" onclick="window.open(this.href);return false;

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V74-4KCPV28-4&_user=861681&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1032372811&_rerunOrigin=google&_acct=C000046147&_version=1&_urlVersion=0&_userid=861681&md5=a9fd1b0ebaa85f69844f11f8b5a9e7a3" onclick=“window.open(this.href);return false;



http://www.foodstandards.gov.au/_srcfiles/FAR_Final_A562_Copper_Citrate_as_a_PA_in_Wine.pdf#search=“copper%20wine”” onclick="window.open(this.href);return false;

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.

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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.

35

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" onclick="window.open(this.href);return false;

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Here’s another perspective published in July of [edit: last] year by Wine Business Monthly:

Excessive Copper Fining of Wines Sealed Under Screwcaps" onclick="window.open(this.href);return false;

Several additional sections and tables in this article are worth scrutinizing as well.

July 15, 2008
Excessive Copper Fining of Wines Sealed Under Screwcaps
Identifying and Treating Reductive Winemaking Characters
by Geoff Cowey



The Australian WineResearch Institute’s (AWRI) industry services team provides winemaking consultancy and technical problem solving services to the Australian wine sector. The team is in the unique position to observe sector-wide trends on a year-by-year basis. One trend we have observed since the larger acceptance and use of the screwcap closure is an increase in copper additions to wines immediately prior to bottling, regardless if any reductive characters are detected in the wine. This is reportedly being done as a measure to safeguard or to prevent any possible reductive character forming in wine sealed with this type of closure.

The issue of reductive character development in wine sealed with a screwcap closure was first observed by the AWRI during tastings conducted as a part of an AWRI closure trial initiated in 1999. A reductive character was observed in the 1999 Semillon wine sealed with a screwcap closure during tastings conducted 18 months after bottling (Godden et al. 2001). The reductive character continued to be observed at each subsequent tasting up to 63 months after bottling. Factors that were thought to be related to the formation of reductive characters were investigated during another closure trial conducted in 2002. The sulphur dioxide concentration and ullage distances were varied in wines sealed with a screwcap closure; both of which showed no correlation with reductive character development. Investigations to determine if reductive character development was caused specifically by use of a screwcap closure were conducted in 2005 by sealing wine in glass ampoules and under a screwcap closure. This trial showed the same level of reductive character was perceived by tasters during tastings conducted four years after bottling (Skouroumounis et al. 2005).

…

The recommended safe levels for the concentration of copper in wine, above which a haze might occur, are summarised in Table 1. Recent changes to the Australian Food Standards Code (Standard 4.5.1) have abolished the previous Australian legal maximum copper concentration of 5.0mg/L, however, maximum allowable levels do exist in other countries (e.g. wine exported to the United States and the European Union require a concentration below 0.5 and 1.0mg/L respectively).

(Editor’s Note: In the U.S., copper sulfate is listed by the TTB for use in removing hydrogen sulfide and other mercaptans from wine. T.D. TTB–17 raised the allowable quantity of copper sulfate from 0.5 to 6 parts per million, but kept the allowable residual level at 0.5 part per million.)

…

Data obtained from the AWRI’s analytical service database of analytical results, showing the average copper concentrations in red and white commercially bottled wine for the past six vintages, are presented in Table 2. Whilst the average concentration of copper appears to have remained relatively constant in white wine, the average copper concentration in red wine does appear to have risen during 2006. These data include only commercially bottled wines sealed with any type of closure.

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Hi Paul,

Thank you for your contribution to this discussion. I am not sure of what is precisely your affiliation with Quarry Hill Wines in Canberra, but based on your insightful comments I assume that you are a principal or directly involved in the winemaking here. I noticed from your website that you have only recently begun to offer the Quarry Hill wines under your own label for sale in bottle, and so was curious as to which closure(s) you selected for your wines. I would also find it interesting to hear how you arrived at this selection(s)- i.e. which scientific research you relied upon, which trials you ran between various closures, which respected winemakers you sought out for advice etc. I noted your comments above that you will only cellar semillon and riesling these days sealed under screwcap, and from this I inferred that you feel that SC is more suitable for certain varietals- or to phrase it differently, certain varietals perform better in the cellar when sealed under SC. Again, I would be very interested to hear how you arrived at this conclusion, as I observed that I do not have any wines sealed under screwcap in my own cellar for long-term aging and do not have any first-hand experience in this regard.

One small factual correction, if I may. You incorrectly attributed to me the assertion that “there was a quiet change last August that deleted the limits on the use and residuals of copper in Australian wine”, which I never stated. You may have taken this from an interview I conducted in August of 2008 with Dr. Paul White, in which he said:

“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.”

I underscore that this interview was conducted in August of 2008, so he would be referring to changes that would have occurred in August of 2007. Now both you and Dr. White, as residents of Australia and New Zealand respectively, are much better positioned than I in New York to know whether or not there were any changes in this regard with FSANZ in the summer of '07, or if your citation of the changes that took place in 1999 were the last regarding residual copper in wine. I have asked Dr. White to participate in our discussion so that he can clarify his statement, which he will shortly do, once he returns from a European trip.

In the interim, I am perfectly content to accept your assertion that the abolition of maximum levels of residual copper in wine (and other foods) was undertaken in 1999 by FSANZ. As you are also much better placed to know than I, 1999 was when screwcaps first really began to gain traction as wine closures in Australia and New Zealand, and this would have predated by a few years both the wholesale adoption of this closure and the growing incidence of reduction problems observed with wines sealed under SC, that to the best of my recollection only really began to be written about in some scientific journals in 2003 and 2004. So, of course, no collusion between “soulless wine technocrats” and FSANZ could have occurred in 1999 (which you seem to think that I inferred), as in 1999 one assumes that no one would have had even an inkling that reduction was going to be an issue with wines sealed under SC and that widespread adoption of copper fining would be seen as the answer.

But your pegging FSANZ’s abolition of maximum residual copper levels in wine to 1999 also calls into question the research that they would have relied upon in making this decision, as it is quite logical to infer that the incidence of elevated residual copper levels in wine in Australia and New Zealand in the mid to late 1990s (when such research would have had to take place) was nowhere near the same level as it is today with the widespread utilization of SC. If this were indeed not the case, then why on earth would AWRI publish a paper by Geoff Cowey in April of 2008 entitled “Excessive Copper Fining of Wines Sealed Under Screwcaps” in the publication, The Australian and New Zealand Grapegrower and Winemaker? In the paper of course, Mr. Cowey cites statistical evidence that elevated levels or residual copper in Australsian wines are indeed on the rise in the last few years.

Given the evidence of the increase in wines in Australasia with elevated levels of residual copper in the last few years, it seems to me that it is perfectly reasonable to ask why FSANZ has not moved recently to look into this issue, which they are clearly aware of based on the citation posted by Mitch revolving around the inclusion of cupric citrate (without a bentonite base) to the list of accepted wine additives for Australian and New Zealand wines. If, as it seems on the surface, that FSANZ continues to rely upon research conducted in the mid to late 1990s in this regard (which I infer from your assessment that the 1999 abolition of maximum levels of residual copper in wine was the last such action undertaken by FSANZ), one clearly has to question the relevancy of this research in light of the well-documented increase in the number of wines in Australasia these days with elevated levels of residual copper in them. In my opinion, for FSANZ to not address this issue could certainly be construed as questionable.

In any event, I am sure that you construe my interest in this subject as an example of “Australian and New Zealand wine bashing” (I think the term you concisely used was “bigotry”), but this is in fact not the case at all. I am very concerned about residual levels of copper in my wine that could potentially pose a public health risk, irregardless of their origins- be they wines made in France, California, Tibet, Manhattan or the moon. The reason that this conversation is focused on Australasian wines has everything to do with the 1999 decision by FSANZ to abolish maximum levels for residual copper (and attendant testing) and the very clear evidence that residual copper levels are on the rise in both Australia and New Zealand. In light of the fact that FSANZ has no limit and no testing for residual copper, concern for potential public health risks is not misplaced at this time. With other wine-producing regions where screwcaps have also been adopted, there is at least maximum levels set and testing, and so at the very least there is a mechanism in place that can be used to avert a potential public health problem.

I am sure that you are well aware of the 2006 Te Kairanga Pinot Noir from New Zealand that was rejected by the EU and returned to the winery after it tested out at 2.4 mg per liter of residual copper (nearly five times what would have been deemed safe for human consumption prior to the 1999 abolition of maximum levels by FSANZ). While you may take exception with my alarm with a 2.4 mg per liter level in the Te Kairanga Pinot, the reality is that this wine was only spotted because the European importer decided to have the wine tested himself, as GATT regulations would have allowed the wine to be imported into the EU without any testing, given that the wine had been produced under the auspices of safe production regulations in its home country. Presently, without FSANZ maximum levels and testing for residual copper, one is left simply speculating on how many other wines with levels of residual copper deemed unsafe for human consumption are floating around in markets and completely-unaware consumers’ cellars due to sailing through the sieve created by GATT on this issue.

Now we could go back and forth on the issue of whether or not screwcaps as a wine closure are responsible for the higher incidence of permanently reduced wines out there these days- you could even go so far as to personally doubt that reduction is even an issue with SC-sealed wines and continue to cite anedoctal evidence that wines do wonderfully under SC. You are certainly free to do so. But the growing evidence of dramatically higher incidence of copper fining being utilized pre-bottling for wines in Australia and New Zealand (cited for example in the AWRI paper authored by Mr Cowey in April of '08 or evidenced by the recent allowance by the FSANZ of cupric citrate as a wine processing aid) is a clear indication that reduction is indeed a problem, whether or not you or anyone else on the production side of Australasian wines chooses to publicly admit it.

Either that, or all of the Australian winemakers making wines back in the mid-1990s or 1980s or earlier were blithering idiots who knew nothing at all about wine chemistry and were utterly ignorant of the necessity of copper fining their wines prior to bottling to prepare them properly, and we have all been drinking permanently reduced plonk from that era because those winemakers were not responsible enough to add copper to their own wines back then before bottling them. You can choose to believe whatever you like in this regard- for me, I have a pretty healthy respect for those great old Australian wines that I have drunk and the people who crafted them, and much less respect for the opinions I see emanating from many directions in this contemporary debate. Or maybe it was just that the old timers simply had their hands tied by the old maximum level set by the FSANZ back in the dark age prior to their enlightenment in 1999, and if those winemakers had been free at that time to exercise their own best judgement, all those great old Australian wines would also have had copper levels nearly five times what is considered safe here in the states for human consumption.

Best,

John

38

Hi Mitch,

Thank you for your insight into the potential preference of cupric citrate over copper sulphate as a fining agent to address reduction tendencies in wines pre-bottling. I had read Mr. Cowey’s article before and found it a fascinating look behind the scenes, as well as a very clear indication that AWRI’s science in regards to these questions was moving in what looked to me to be a positive direction. Happily, there is no mention here of “sulphide equilibria” and other errors of the past. I noted in the table that Mr. Cowey constructed of the average copper concentration of commercially bottled wines that the incidence of residual copper was up dramatically for red wines included in the survey from vintage 2006, with the increase markedly more than was the case for the also increasing incidence of white wines from this vintage. This speaks to your observation that tannins are a likely to bond with copper additions and retain more in the wine after filtering.

Given that one of the restrictions cited by FSANZ that would inhibit winemakers (policing themselves) from excessive additions of copper to the wine was the formation of a haze from residual copper above a certain threshold- which FSANZ observes would be much less detectable in red wines- the higher incidence of residual copper in red wines cited by Mr. Cowey certainly supports your science in this regard. What I would find most interesting to learn is what are the percentages of red wines versus white wines that are submitted to AWRI for post-blue fining analysis, as this could be a good indicator of whether or not self-policing is workable in regards to residual copper in wines from Australasia. If the samples submited post-blue fining were in line with the statistical breakdown of white wine production versus red wine production, then it would seem that self-policing could be a workable solution, as it would indicate to me that blue finings to remove excesses of copper were being applied to both reds and whites, despite the fact that only white wines would give visual indication of excessive levels of copper, through the formation of a haze. But if the blue fining tests conducted by AWRI are skewed towards white wines, it would tend to indicate to me that self-policing would not be a workable solution, as the prima facie evidence would suggest that winemakers are more concerned with the aesthetics of the finished wine, rather than its potential adverse affect on public health.

Best,

John

39

The following excerpts are from an article titled Mercaptans and other volatile sulfur compounds in wine by Jamie Goode: http://www.wineanorak.com/mercaptansinwine.htm" onclick="window.open(this.href);return false;

Now the really controversial bit. Can you believe it? Sulfur compounds in wine—‘reduction’—has been in the national press in the last few weeks. The Daily Telegraph carried a story titled ‘Screwcaps blamed for tainting wine’ on 19th September, which was also picked up by other news outlets. This was prompted by the results of the faults clinic from the 2006 International Wine Challenge (IWC). ‘In a number of cases the IWC chairmen validated a link between screw cap use and a unfavourable vegetal/rubber flavoured compound—presumed to be a complexed sulfide’, reports Sam Harrop MW, who was one of the four IWC chairs. ‘At first glance a percentage of 4.9% of total faults may not seem high, but when examined in the context of total screw cap figures, a more worrying rate of 2.2% [of all screwcapped wines] emerges. In the context of the 2006 IWC cork taint figure of 2.8% [of all natural cork-sealed wines], this fault type is significant and should be given more attention by wineries using screwcap.’ However, Harrop is keen to emphasize that he’s not equating the two: ‘While the IWC figures for screwcaps are a concern, there is no question in my mind that the continued incidence of cork taint is still a more serious issue.’

The potential problem with sulfides in screwcapped wines first came to the wine world’s attention through the magnificent closures study began by the Australian Wine Research Institute (AWRI) in 1999, and which has been reported on at regular intervals as the wine (a 1999 Semillon from the Clare Valley) has developed under a range of some 14 different closures. Included in this study was a metal-lined screwcap. The liner is important here: the oxygen transmission properties of a screwcap are determined by its nature. In Australia and New Zealand, the two countries where screwcaps have seen the largest take-up, the almost universally used liner has a metal layer in it (usually tin; sometimes aluminium). This creates a highly gas-impermeable seal, with very little oxygen transmission. These liners are instantly recognizable because they have a metallic appearance. The other commonly used screwcap liners for wine appear white—these are known as saranex-only liners and allow more oxygen transmission, although probably a bit more than is needed just to avoid reduction, and likely more than we’d want of a closure for wines destined for keeping for more than a few years.

In the first major report from this closure trial, 20 months on, the AWRI reported that the tin-lined screwcaps performed as expected: with their tight seals they kept the wine freshest, and the screwcapped bottles scored highest for fruity aromas, maintaining the highest levels of free sulfur dioxide while showing the least colour development. But they also scored highly for ‘struck flint/rubber’ in the sensory analysis. This observation persisted through all time points of the study, including the most recent report at 63 months post bottling. Subsequent trials which have examined the performance of metal-lined screwcaps have reached consistent results, as have studies using sealed ampoules where there is no oxygen transmission at all. ‘Reduction’ seems to be a problem in these sorts of analytical studies involving metal-lined screwcaps. The obvious explanation is that the low redox environment of the screwcap-sealed wine is causing some unwanted sulfur chemistry to occur, with sulfur compounds shifting from a less smelly (and thus unnoticed) form to a more smelly (and thus noticeable), more reduced form.


…
Since the publication of the first AWRI report in 2001, there has been just a trickle of data on the subject of screwcap reduction. But little by little a clearer picture has emerged, and I would go so far as to say that the current weight of evidence suggests that the issue of mercaptans in screwcapped wines is problematic enough that some caution should be exercised in their use. First we have the consistency of the observation: where people have been looking carefully at screwcapped wines, these mercaptans (or what people believe to be mercaptans from sensory analysis) have always been found.

…
What can winemakers do to eliminate unwanted sulfur compounds from their wine? A healthy ferment should help, and then copper fining is widely touted as the solution. This certainly gets rid of mercaptans, but it doesn’t eliminate disulfides which can, as we have seen, can revert in a low redox environment to mercaptans. For this reason, Limmer calls copper fining ‘the Ambulance at the bottom of the cliff’. Besides, copper fining will also remove the desirable sulfides which are important for varietal character in Sauvignon Blanc and other grapes.

…

Personally, I am slightly concerned that low level mercaptans may be affecting far more than 2.2% of wines sealed with screwcaps. ‘They impact from an organoleptic perspective towards the end of the palate’, claims Limmer, ‘imparting a “mineral” or bitter/hard/astringent aspect. This has the appearance of shortening or closing up the palate, so the wine does not display a fine fresh long finish, but ends abruptly, and somewhat harshly.’ This is describing something I’ve certainly noticed in side-by-side comparisons of cork and screwcap-sealed wines. Is it happening all the time, but going more-or-less undetected?

Gregor Christie of membrane cork company ProCork has been concerned enough about this problem that he has sent of wines for testing at ETS laboratories in California. Clearly, Christie has a commercial imperative for showing that ProCork is superior to tin-lined screwcaps in this regard, but even given this motivation, the results are interesting. Christie took the 2002 Clare Valley Semillon used in the commercial closure trial run by the AWRI, comparing ProCork with natural cork and screwcap, and submitted bottles sealed with all three closures to ETS for testing for a range of volatile sulfur compounds. For methyl mercaptan, which has a perception threshold of 0.3 parts per billion (ppb), both the cork- and ProCork-sealed bottles were below detection limit. However, the screwcapped bottle showed a level of 0.6 ppb, above perception threshold.

But a sense of perspective is called for here. There’s a real danger that the message that is distilled by journalists from all this technical talk becomes a misleading ‘screwcaps taint wine’ story. The picture emerging is a complex one, but such a simplification would be dangerous if it caused producers to back away from adopting alternative closure solutions, which would then have the knock-on effect of removing any incentive from the cork industry to put its house in order and do all it can to reduce taint levels. However, complications like this mercaptan issue should put pressure on winemakers to be more curious about the closures they are using. They should ask more questions about issues like oxygen transmission, and insist on seeing independently validated data on closure performance rather than accepting manufacturer’s testimonials or sales pitches unquestioningly.
Article originally appeared in Harpers Wine & Spirit Weekly in 2006. Posted here February 2007. Copyright Jamie Goode

40

It was suggested to me that this thread be moved to Wine Talk to engage even more individuals in the discussion (those who do not venture into Cellar Rats all that often) as it has turned into a very valuable discussion regarding screwcaps, reduction, and the inclusino of heavy metals in wines that many of us might like to discuss as well.

Thank you John for the suggestion!