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

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

"Marc Dostie" > wrote in message
news:9M17d.12611$sP2.10042@trndny04...
> 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

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.

> 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

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.

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:
> 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

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:

> 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.
>

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:

> 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.
>

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

"Marc Dostie" > wrote in message
...
> 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
>