H2S during hot fermentation

Joe, RC212 is know to produce more H2S than other strains especially when stressed for nutrients

I would serious consider another dose of quality yeast food like Fermaid or Superfood - not just DAP. A little stirring when you punch down the cap (or mixing around if juice) might not hurt either. RD

Joe, RC212 is known to produce more H2S than other strains especially when stressed for nutrients

I would seriously consider another dose of quality yeast food like Fermaid or Superfood - not just DAP. A little stirring when you punch down the cap (or mixing around if juice) might not hurt either. RD

Thanks for the link on yeast characteristics. I gave it another light shot of nutrient. According to the label it is mostly DAP. The ferementation has slowed down and the H2S smell is much less. It looks like it will be ready to press in a couple of days. Joe

I very highly recommend that after pressing you let the wine settle for an hour or two and give it a racking away from the heavy lees. Keep that part separately to reclaim what wine you can from it, but if it develops H2S stink don't mix it back into the main batch.

Tom S

Thanks for the suggestion Tom! I usually press into DJ(s) and after a few days rack off the gross lees. It makes sense to rack off the heavy lees sooner in this case. Does that mean I have to rack again in a day or 2 before MLF?

Joe

No. Leaving the wine on the fine lees is OK, and may actually promote ML.

More and more I see commercial winemakers going straight from the press into barrels, but I think that going to that extreme is needlessly risky.

Tom S

I agree, Tom. Here is my experience:

I rack off the gross lees within 24 hours after pessing. I like to work in 200 lb lots since my press holds 200 pounds of must and that way I empty two 15 gallon fermentation containers which hold 100 lbs of crushed grapes each.

From two hundred pounds of pressed grapes I get about a gallon of gross lees after racking - somethimes a little more. I put these gross lees in a gallon container or half gallon containers. After one or two days there is about 1/2 the volume of clear wine on top. I then rack or decant this off. If the gross lees are left for three days or longer without racking, H2S is there in a big way. This is true whether I have the lees outside where it is chilly or inside where it is warmer.

I think going directly into barrels is a BAD idea and I have seen both wine and barrels ruined in this approach. The wine can be cleaned up with work, but the barrels are not as easy.

Making 'hobby' zin (3rd year) with Sonoma County CA Russian River grapes, which tend to produce jammy zinfandel wine.

I'm torn between the added pepperiness contributed by using a small amount of 'soft' raisin grapes (maybe 5% by weight) and the jamminess due to using such low acid fruit as part of my must.

How do other zin lovers cope with jammy zin grapes?

Gene

You could make some Sangiovese which is generally more acidic and then blend the two by taste until you find a ratio you like.

One other thing that can commonly contribute to H2S is the fermentation "choking"--what I mean is that if you ferment in a vessel that does not let CO2 escape quickly enough (i.e. I know people that do their primary fermentation in a pail with the lid on--with just an airlock to let gas escape), this can result in H2S.

If you are fermenting with the lid just sitting loosely on the fermentor or with a towel covering or whatever, then this isn't the problem--it's likely just a lack of nutrients, which you seem to have addressed.

One other thing that can commonly contribute to H2S is the fermentation "choking"--what I mean is that if you ferment in a vessel that does not let CO2 escape quickly enough (i.e. I know people that do their primary fermentation in a pail with the lid on--with just an airlock to let gas escape), this can result in H2S.

If you are fermenting with the lid just sitting loosely on the fermentor or with a towel covering or whatever, then this isn't the problem--it's likely just a lack of nutrients, which you seem to have addressed.

I didn't know that either CJ and runs contrary to my experience. Care to explain/expand or give a reference.

Andy