I'm going to rack a barrel that I think has some modest H2S and I'm wondering whether I can achieve the same effect by sparging the barrel of wine with O2. It seems a lot easier that moving all that wine around (without a pump). Thoughts?
You don't want to pump O2 through your wine unless you're making wine vinegar. If the wine has just a slight case of H2S you can probably get rid of it by stirring with a clean section of copper pipe. Hanging sterling silver in it works too.
(This may be a re-post) What's the difference between the oxygen contact from racking and oxygen contact from pumping directly into the wine? I've got copper sulfate and could get a copper pipe, but my understanding was that you needed to rack off whatever preciptates out shortly anyway and I'm trying to avoid racking.
If it is sitting on lees, they are often the source of the H2S (a reductive environment). Racking therefore has two advantages, you remove the source of the problem, and a LITTLE air during racking will get rid of the H2S. Bubbling air through is not recommended unless you have a commercial micro-ox unit, and you're dealing with at least 2-3000L, because the air contact is so extreme compared to racking.
I guess I won't ask why I can't just run a LITTLE air through a tank. So this is the first I've heard about having to dump my lees. Note that the wine pretty much smelled like this within a few days of putting it into barrel. Also note that the barrel was heavily sulphered when the wine went in. I gave it plenty of nutrients during fermentation. What's the probability that the lees are the source?
Have to agree with Tom - lees are almost definitely the culprit. Yes, you could run a little air through a tank, but it is extremely hard to control. For instance I wouldn't recommend bubbling enough that you actually get bubbles at the surface, because this may indicate that you are saturating the wine with oxygen - bad thing. You're going to have to rack anyhow, and it is one of the best ways of getting a limited amount of air in, so look on it as being a good thing for your wine, pain in the whatsit that it is.
Based on Tom's suggestion a few years ago I hung a small piece of sterling in a barrel that had a moderate H2S smell and was quite surprised that this totally solved the problem. I did however, rack it off the lees at that point. I don't believe I added DAP (diammonium phosphate) as it was a little too late for that.
It is a very decent bordeaux-styled blend and the wine is safely ageing in bottles.
FYI, the difference between sparging and racking is also that racking releases dissolved gas but sparging with O2 just forces the incoming gas into solution. You wanna sparge, you sparge with argon or nitrogen...NOT air NOT O2.
But the barrel--it is standard practice to burn sulfur inside for storage--it produces SO2 in situ. Such a barrel is supposed to be rinsed with a 1% citric acid+1% metabisulfite solution, and then rinsed with clear water until there is no smell, and the immediately filled with wine (see Pambianchi book).
So also, the gross lees do not go into the barrel. You rack into the barrel from the primary fermentation. The fine lees dropped are enough to produce the "sur lie" style if that's what you want.
More details... this was actually one out of four barrels. The other three barrels are fine and have not had any H2S problem. They all went into the same type and source of 2 year old oak. The only difference was this batch was heavily "manipulated" while the others were minimally processed. Specifically, the differences are:
Innoculated with cultured yeast
30 ppm sulfites added at crush
Enzymes added
Fermaid added
Hot ferment (let it get to about 95F for a day)
The other three barrels (that are fine) were all native yeast, < 20ppm sulfites, no enzymes, no fermaid and fermented < 85F.
Does any of this correlate with H2S? If not, what's the chance that it was the barrel?
OK, 12 ml of 1% copper sulfate has been added. Stirred it up and I'll check it out tomororrow. Assuming the H2S is gone, then I'll rack it. I intend to transfer the lees with some wine to a carboy and keep it. My thought is that if I "quarantine" the lees for awhile and the H2S doesn't return, then I can just put it back in. Thoughts?
If the lees are the source of H2S and I quarantine them with a couple of gallons of wine and it doesn't stink after a month or two, then what's the argument against returning them to the barrel? The argument for seems to be the additional complexity that can add. But, like most of winemaking, it seems to be more tradition and opinion than anything else.
As I posted elsewhere, the copper sulfate worked like a charm - thanks! I was quite surprised to find the offending odor completely gone when I checked tonight.
This could be it - the hot ferment may have stressed the yeast. Cultured yeast are generally bred not to produce H2S and to withstand sulphur dioxide. Enzymes should reduce the propensity to get smelly, unless you then super-clarified the juice. Fermaid should have reduced H2S, unless it doesn't contain any nitrogen - DAP is habitually added commercially.
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