How do you prevent H2S from starting?

Rob,

There are a few ways to minimize the risk of H2S.

Avoid yeasts that are known to have a tendency to cause H2S such as Montrachet. Make sure your must has adequate nutrient by adding DAP (diammonium phosphate). Keep the wine off the autolyzed yeast as much as possible by racking it frequently.

Others may have more suggestions.

Glen Duff

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Rob wrote:

Two things that come to mind:

1. The sulfite additions seems excessive, especially the second one to bring it to 50ppm. Maybe the sulfur is coming from this?

1. Always add yeast nutrient and/or DAP as Glen said. Yeasts need nitrogen and can develop H2S problems if they don't get enough. Also, I heard Riesling is one the musts that can easily develop H2S, so adequate nutrients are important. You should also consider building a healthy yeast population by rehydrating in Startup or GoFerm and making a starter.

Pp

I agree that the sulphite additions seemed excessive, although I've had in the past found that my experience with campden, what should be

That does raise another question on technique - if there's something converting sulphite to sulfur, how do you avoid that?

Finally, I did use Go-Ferm in making the starter. The yeast, especially the RHST, ran very strong for those first couple of hours; I had no concern as to whether or not fermentation had begun. Whatever happened caught up to a solid fermentation from behind and shut it down.

For those making Riesling from grapes, how often do you rack it during primary fermentation?

Rob

The Go-Ferm is a rehydrating nutrient to make the yeast start strong. It's not the same as regular yeast nutrient like Fermaid K, Superfood or DAP. Specifically, in terms of H2S prevention, these nutrients supply the yeast with nitrogen. So if this was a grape must, my guess would be the lack of yeast nutrients was the culprit - you've got the fermentation to a good start with Go Ferm, but then the yeast got stressed.

I don't think there is any need for racking, if you let the pressed juice settle and clarify and ferment the clarified juice only. But it might depend on the yeast you're using, some of them need additional oxygen during fermentation.

Pp

There are 2 things you can do that would help a lot: (1) Cold settle the juice thoroughly and rack away from the sediment prior to fermentation. (2) Use adequate levels of yeast nutrient, added in stages, during fermentation.

A third suggestion is to avoid yeast strains that have a known tendency to produce H2S.

Tom S

Thanks, guys, for all the ideas. I appreciate the help, and hope to do better next time.

Rob