Lets say you are not "entirely" sure that what you have is H2S (even though you are pretty sure), so you want to add some copper sulfate. Can copper sulfate pull out "good" aromas unintentionally?
Thanks!
Joe
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Copper will not pull out good aromas Joe, but it can make wine more prone to oxidation.
Lum Del Mar, California, USA
The danger with oxidation mainly occurs with residual copper, and if proper sulfite levels are maintained during the treatment, the danger can be avoided altogether. At proper dosage, there is little to no residual copper in the wine.
Like all fining agents, copper sulfate additions should be determined by trials, so the minimum dosage is used to create the desired effect. Trials will also help determine if the problem is indeed H2S (or some other reduced sulfur compound).
I have noticed before a temporary muting of positive wine qualities during trials. I don't know the vehicles involved, but the wine has always recovered over time.
clyde Steelville, Missouri, USofA
Clyde, or anyone else. I am interested it trying this on a batch of wine as well. I have never use copper sulfate before. Could you suggest a procedure for running trials and what to look for to get the right amount?
Ray
Legal limit of residual Cu here in the US for commercial wine is 0.5 ppm. Copper haze can form in whites with as low as 0.4 ppm residual Cu.
H2S (and other sulfides) will fatique the nose very quickly, so I always setup a trial doing several samples (0.4 - 0.1 ppm) and check from the largest dosage to the smallest.
Like most fining trials, results will be slightly off, usually to the lesser side. One possible cause for this is that the dilution rate is dramatically different from actual cellar procedures, but human error in measuring small quantities probably has a larger role. I tend to bump my results up by at least 0.05 ppm. In other words, if trials dictate an addition of 0.3 ml of 1% CuSoO4 per Gallon, I would probably add 0.35 ml.
As Lum already pointed out, presence of CuSO4 tends to hasten oxidation, so SO2 levels need to be kept at appropriate levels while treating the wine.
Also, almost all finings will reduce free SO2 levels to some degree, so monitoring levels before and after becomes very important.
Hello All,
BASF has a product called Divergan HM that removed heavy metals from wine and beer. Has anyone used this product after CuSO4 treatment?? Also, does anyone have a source to buy??
CHEERS TO ALL!!!
Aaron
I have always noticed that copper does seem to deaden the nose, and contrary to other posters, the freshness doesn't come back. This is quite possibly due to oxidation of volatiles by the copper. However, as H2S also deadens fruit characters, it is a question of balancing one against the other - just like all winemaking practices!
Help me understand this Andrew. Are you saying that you have a wine that has H2S aroma with some nice freshness in the background and then after copper fining it looses some of that freshness and then never recovers??
You must have quite the distinguishing palate!
clyde Steelville, Missouri, USofA
No, but I've used rehydrated yeast (30g/HL) to take out residual copper, and it's worked really well. I've taken out large (ahem, ahem) amounts of copper, and haven't had a problem with residual "yeastiness."
Dave
**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com
No, I really meant it suppresses fruit characters! But I guess I meant that by the copper "deadening" the nose, what it did was suppress the fresh characters that come from the fruit. Did I weasel out successfully?
You may be right about "suppresses fruit characters" Andrew. I don't use copper unless the stench is pretty bad, and I can't detect the underlying fruit character.
Yes. You are a successful weaseler outer.
I've been reading everyone's comments about the use of CuSO4. Last year, I had
2 carboys of the same batch of smelly zinfandel. In one batch, I carefully measured the appropriate dose of copper sulfate. In the other batch, I took a sheet of copper foil (the kind sold in the craft stores). I cut it into 1 inch wide strips, tied them together, and then swished them in the wine for a while.Both methods seemed to effectively take out the H2S. While I have no idea how much residual copper was left in the wine with the second method, it "seemed" safe.
Has anyone else used simple copper? I've read about swishing in copper wire, or even dropping in a few pennies.
Lee
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