In May 2017, I attempted to gather some information and answers about the possible role of the corks in creating poor seals in the “prem-oxed” white Burgundies, that might have led to premature oxidation, mainly by letting protective SO2 out in the random “bad” bottles. I spoke to the Cork Quality Council twice. Though I never received any real answers to the questions I posed, I did write them out when it became clear that I needed to to have any hope a becoming educated by them. I asked these questions , and post them, so that interested parties/posters can understand the potential role of the corks and seals Dustin Mowe, whose company is one of five founding sponsors of the Cork Quality Council has offered to supply answers to my questions, on another , ongoing thread. Because of its importance in this premox mystery…I think it deserves its own thread.
The written questions I submitted in May 2017 to the cork “industry” in California follow:
• _Cork Questions
• What changed and when, etc.?
• The switch from cork to paraffin was when?
• When did the industry start adding silicone to the mix?
• Did that make the corks more rigid? What effect did it have on the finished corks if not?
• Does the amount of silicone coating vary among the producers…by a lot?
• Does the method you described for both adding paraffin (the football sized block) or used when silicone was added, make for a uniform application on each cork? Or is the amount of each variable? (It is hard to imagine how that works and provides uniformity for the non-scientist like me.) Is centrifugal force involved to make it uniform?
• When and how did cork drying start? And, do you think any of the large producers made any corks too dry? Is there such a point…that the rigidity of the cork is more like a dry sponge than a moist one? How is it done and when in the process?
• If the corks were made more rigid as a result of any/all of the above, what allows the corks to make as good a seal as when just paraffin was used and no drying was done? It sounds like it would be very difficult the more rigid a cork gets.
• Did the producers tell anyone, i.e., allow them to opt out of any of these improvements? (My experience in Burgundy is that the producers had no idea anything had even changed until a few vintages in, when some demanded non-silicone covered ones to avoid rigidity. Could they still get them?
• Does silicone coating or drying contribute more to a rigid cork?
• I read today that an estate in Chablis which switched to DIAM or screw top…or both…had NO issues with those closures, but in vintages where real “corks” were used, there were lots of problems with prematurely oxidized bottles within given cases.
• I realize that transfer of oxygen is much better with real corks, and that is a reason to use them, but has your industry ever done studies on the rates of failures, i.e., not due to TCA…with bottles under cork, particularly from the mid-90s?
• Yesterday, I watched several YouTube videos on cork production…very educational. Are there any you recommend that address/show the changes in methods of production (i.e., coating and drying) and how they were done?
• Clearly, something changed dramatically with White Burgundy (WB) and the rates of premature oxidation from the mid-90s vintages…and some producers had lots of it…and others not so much…and it often varied from year to year at any given estate.
• So, the wine and the closures are the likely candidates. I know nothing much about winemaking, but I’ve had 20 year old WB recently that were flawless…and under cork. So, the wine is, IMO, fine, even if more vulnerable. And, from a case of them….4 were totally oxidized.
• I am not trying to indict the corks, but to try to understand the variables between a good bottle of a particular producer’s lot in a given year…if the wine is all the same. (I know oxygen rates are variable…with the ullage and other oxygen, but….my guess is that the variations were MUCH more in the ‘80s when this problem never occurred…though it did somewhat in the 1989 vintage.
• And, as I told you one producer showed me in 2007 that with the good bottles, the SO2 levels were the same at bottling; in the bad bottles, it was all gone. You said that the oxygen would essentially “eat up” the SO2, but…why did this almost never happen before the ‘90s? Could the SO2 “escape” with a poor seal at the bottle neck…or is this not possible? Would oxygen come in with a bad seal? Or SO2 go out….or both?
• Does the cork industry have any research it did/does about its possible involvement in the prem-ox issue? If someone is looking to do some, I have a perfect producer in WB to use…….He only sells his wine when mature…it sits in refrigerator temperatures until then (thus impossible to taste in Meursault), so he releases at 10 years, white and red, at the earliest. And, since I last visited, he has had a stroke …and since he single and has no heirs….he probably would be happy to cooperate. (I used to know his importer into the US very well and could contact him if your “people” wanted to check it out. My idea would be to see what’s different with bad bottles…even if kept in pristine conditions. (I have no idea whether his were or were not affected by the premox.) Just an idea.
• My own informal “survey” over the last 20 years of WB…I stopped buying in 2007; my wife said I was too old and had too much wine…and I’m glad she did. My survey convinces me that when there is a good bottle, the cork, at least part of it near the headspace, is as moist as always, if only on the bottom? (And does the bottom of a cork get coated…or just the sides?)
• I find this fascinating, though I don’t think the issue if as much one of science as it is common sense and bad closures. So, I really appreciate your thoughts here.
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