It definitely works. It was shown to me by Niels Verburg the winemaker at Luddite. He was showing early barrel samples and demonstrated the technique. Wine was instantly softened. Brilliant wine too. https://luddite.co.za/
Do bacteria survive on copper? I would have thought not…
Like on a twopence piece?? interesting
An OLD two-pence piece. The newer, smaller ones are some iron alloy (a.k.a. steel) presumably coated. Whether the coating is or contains copper I can’t say. I haven’t investigated!
But again, beware. Copper use is a winemaking thing - wines under screwcap need a different pre-bottle finishing to avoid going overtly reductive. But it will change the flavour and not necessarily for the better - the flavour compounds in cabernet sauvignon and sauvignon blanc particularly involve thiols which are very definitely part of the whole, and it will strip them out.
(Conversely too much copper in a wine can lead to other problems, but that’s beyond this discussion and more of a winemaking thing).
I guess it does not survive on copper, but it does on all the dirt stuck on that piece of copper
You would need to keep a dedicated clean piece of copper at hand… or even better a pure copper wine glass
I think it unlikely it is real copper because:
- There is a silver/stainless steel option and they are presented as being purely cosmetic options.
- Copper would almost certainly have some impact on flavour and, whether you consider that beneficial or not, I don’t think that is the job of the eto
- It would require a lot of maintenance to retain its appearance, which is not something most people would be happy with these days.
I sort of like the idea of using copper for reds and silver for whites. Appeals to my aesthetics
from basic chemistry copper actually reacts quite quickly with certain materials - gasoline and diesel for instance
It can be used in refineries to remove free sulphur compounds
You’re absolutely right, but the copper in those situations is never elemental, solid copper metal - it is always activated, catalysed or in some form of copper based reagent. The point I was hinting at is that an old copper coin is none of those things!
“Copper sulfate (CuSO4) is a fining agent used to remove unpleasant hydrogen sulfide (H2S) and other “sulfide-like” off aromas in wine. The hydrogen sulfide is generally described as rotten-egg-like off aromas.H2S is volatile natural product of the fermentation and it can be present into the wine as mono-mercaptans (sulfides), which can be treated with copper or poly-mercaptans (disulfides) which will not react with copper, so deal with the problem as soon as it is detected. Copper when added to wine containing “sulfide-like” off aromas immediately reacts with H2S and form copper sulphide, immediately. If the copper ions is not removed from the wine after the treatment with the proper fining agent or filtered out, a haze may appear. Most of the time copper is added to the wine in the form of Copper Sulfate s(CuSO4•5 H2O), also known as Copper Sulfate solution”
I have been using mine for a few weeks and I am a little disappointed. It is supposed to keep the wine exactly as it was the first time of opening and I have found that they have changed. Considering it took nearly 2 years to come I thought it would be better
It should have a mark on the decanted showing 37.5ml so we know where we are
I’m hoping mine will arrive by mid July… but who knows
They are copper-plated, so should still work providing the plating has not worn off.
My understanding is that the copper removes only hydrogen sulphide - coating the coin with copper sulphide. Mercaptans are too stable, and I’ve never before heard of it as a fix for VA.
Copper is part of the test for mercaptans - it does remove them as well as sulfides. The use of copper in winemaking is discouraged as some mercaptans are essential flavour components (e.g. the passion-fruit flavour in Sauvignon blanc) and copper breaks them down. Though not disulfides and any other higher sulfides apparently.
Test for reductive components in wine
I agree about VA - never heard of that either.
You might be right about copper, but the AWRI page you linked to refers to copper sulphate; not elemental copper. Sadly, google and my home library are incapable of resolving the question one way or another to my satisfaction. Most webpages refer to copper coins removing H2S, but do not comment on mercaptans.
Regarding the use of copper-alloy fittings in winemaking, wouldn’t removing hydrogen sulphide also help prevent the eventual formation of mercaptans?
A slightly leisurely response to you, Steve (sorry). But I think the reaction with copper metal does rely on its solution into ionic Cu2+ form first. Wine is quite acidic so that must be a part of it. I’m not an oenologist so can’t take it any further I’m afraid, as I’m aware there will be other factors too such as the relative kinetics.
If copper is indeed extracted from fittings then I guess what you say may be possible, though they are more likely to be brass I think, and the zinc in brass is more electronegative than copper.