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Strange odor during cabernet fermentation

Well, I've been at it for over 10 years, and this year I decided to make my first Cabernet (80/20 cab/merlot). I've got 8 fermenters going right now, 2 Petite Sirah,

2 Zinfandel, 2 Barberra, and the 2 Cabernet.

The 6 other fermenters smell just the way they should, but the 2 Cabernet are very pungent, giving off a foul odor (or at least not the type of odor I'm expecting). When I press the skins back into the wine, the foam that forms on the top of the grapes is hazy, almost moldy in comparison to the others.

I'm in day 3 of fermentation, is this normal for a Cab? I called the supplier, they said I shouldn't worry, it's probably either a bit of mold or the sulfites that the grapes were sprayed with, and it should "boil off" during fermentation.

Any info is greatly appreciated! Thanks.

-Marc

Reply to
Marc Dostie
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What is the foul smell? Is it like rotten eggs? If it is it's H2S forming, which I've had happen with cabernet. I'd stir it like crazy to aerate it and blow off the hydrogen sulfide, and also consider adding some yeast nutrient - if the must is nutrient deficient it can be a cause of the production of H2S by the yeast.

Ed

Reply to
Ed Marks

I'd be really worried if it was a "bit of mold". There should be no mold and definitely not enough to make a smell. I echo the previous comments about lack of nutrients. I always use 1 teaspoon of nutrient per gallon. Also, what yeast are you using? Sometimes Montrachet can produce an odor.

Reply to
Brewser83

I suggest you check the pH of the must and adjust if necessary. A high pH may be encouraging some things to grow that you do not want to grow.

Reply to
Paul E. Lehmann

Thanks for the suggestions, everyone. We're using my father in law's cellar, and I'll be over there tonight to try to quantify the smell more accurately.

As for nutrients/yeast/additives, we've never used them. Just the grapes and my in laws' 50 year old process. Perhaps it's time to purchase a few measurement instruments.

Thanks.

-Marc

Marc Dostie wrote:

Reply to
Marc Dostie

Ok, I've confirmed with my brother in law that it is an H2S type of smell. Assuming we don't add any nutrients, how many times a day would you recommend we mix these fermenters?

Thanks again.

-Marc

Marc Dostie wrote:

Reply to
Marc Dostie

Assuming it is H2S, you can try to blow if off by stirring or racking with lots of aeration, but I don't think thats going to keep the fermentation process from continuing to produce it. You really should add yeast nutrient if it's not too late, and, you may need to treat the H2S with copper when the fermentation is complete.

Ed

Reply to
Ed Marks

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