Cab Franc H2S - 3+ Weeks Old!

Even quicker - during the first week while fermenting because of inadequate yeast nutrients. Is your wine sitting on a significant amount of lees? I understand this can also cause H2S.

Ed

Definitely significant lees until last weekend when racked. Is there value in adding nutrients now? Since fermentation is still going I would think it theoretically would help inhibit further "growth" but I have obviously missed the window to not let it happen whatsoever.

manifestation

It would only be of value to add nutrient if the wine were not yet dry. After 3+ weeks, it's probably been dry for awhile and the activity you're seeing is ML. Hit it with the copper pipe. That should do the trick. If so, it works quite rapidly. Just stir it vigorously in the carboy until a sample no longer stinks, then stir it a little longer just to be sure. Get someone else to smell the wine for the sake of objectivity.

Tom S

Patrick

A quick couple of questions with your H2S issues. After pressing your grapes when or did you rack off the gross lees? Did you add a commercial ML culture at some time, or are you relying on nature? Did you initially add sulfite to the crushed grapes and if so how much for your total weight of cab franc. Since your attacking the H2S with cooper early you can save this wine. Zinman

I racked off the gross lees 3 weeks after pressing. I've not added, or intend to add, an ML culture but to let nature take it's course. I added 0.5 tsp. sulfite to the 72 lbm. of must before inoculation.

I've added the copper (I poured into a funnel which I fitted with a copper pipe outlet about 16 inches long) and then stirred today with the same copper tubing but still believe I have some H2S left. We'll see over the next day or two. Perhaps the copper fitted to the funnel did not aerate enough.

The initial odor was.. WOAH - big. Hopefully I can rein this in.

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manifestation in

Patrick

Sounds like your problem is very serious. Most yeast produce a small amount of H2S during fermentation, a whiff of rotten egg. Low nutrients in the grape must also stress the yeast and produce the odour. Punching down the cap often and yeast nutients deal with that. Usually aeration after fermentation till the stink is gone followed by sulfite additions cure the problem. However, leaving the wine on the heavy grape solids...GROSS LEES... for three weeks could be and is terminal as the gross lees reduce (rot). There comes a point where hydrogen sulfide will chemically change to another compound called mercaptan. This has a distinct "skunk" aroma and once it has settled into your wine there is no treatment for the home winemaker. It is used in propane and natural gas to alert people to gas leaks. If your wine smells like that dump it and be the wiser next year. If it just smells of rotten egg vigorous racking with metallic cooper(pipe) or "Cufex" may help. Careful with cooper as small amounts are toxic. There is a product called "Bockskin" that bonds to the H2S and removes the stink. Forget about ML fermentation if any of these techniques work as you will need to add more SO2 than the bacteria can survive. Sorry For The Bad News

Zinman, Thanks for the information. It is my understanding that gross lees are the resultant lees from pressing; I did not leave the must lying around for 3 weeks. The caps were punched down 3x per day but no nutrients added.

If you're saying leaving the wine in contact with the lees from pressing for three weeks is poor practice, I am surprised as I've done it over 4 weeks last year for all my wines and the other 6 varieties this year do not exhibit any odors.

I do not believe I've gotten to mercaptan so I am still confident the wine will come back.

If not, I wonder if the vinegarmakers can advise whether wine afflicted with H2S can become a safe, decent vinegar!

Patrick

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Mercaptans (and di-mercaptans) can be dealt with... the di-mercaptans require the addition of asorbic acid and then copper sulfate. The mercaptans can be dealt with copper sulfate, which is certainly available to home-winemakers.

See this post:

HTH