I fermented two batches of wine from Sauvignon Blanc grapes in September
using two different type of yeast, one dry and one semi dry. The dry batch
still reeks of Hydrogen Sulfide after repeated rackings. I used isinglass
in the wine and its crystal clear but still smells like rotten eggs! Is
there anything I can do to get rid of the foul odor? Will is dissipate with
time?

Frank Bacon wrote:
> I fermented two batches of wine from Sauvignon Blanc grapes in September
> using two different type of yeast, one dry and one semi dry. The dry batch
> still reeks of Hydrogen Sulfide after repeated rackings. I used isinglass
> in the wine and its crystal clear but still smells like rotten eggs! Is
> there anything I can do to get rid of the foul odor? Will is dissipate with
> time?
>
>

Commercial wineries use copper sulfate for this purpose, but too much
copper sulfate is toxic, so it must be done with caution. Also, some of
the sulfur may be present in disulfide form, which smells like garlic or
cooked cabbage. The disulfide form requires additional treatment.

Good Luck,
Gene

One of our well-respected members, Lum Eisenman, posted in Feb 2006 on
H2S treatment (see below):

Subject: Can H2S be measured?
From: "Lum Eisenman" >
Date: Fri, 03 Feb 2006 00:03:33 GMT
Newsgroups: rec.crafts.winemaking

"Igor" > wrote in message
oups.com...

>> If you wanted to treat the H2S problem with CuSO4, it would be good
>> to know how much H2S you have, so that you can calculate how much
>> CuSO4 you need. Otherwise, how do you know how much to add?
>>

Igor,

A simple way of removing H2S is to add enough copper sulfate to produce
about 0.1 ppm of copper in the wine. Then the wine should be stirred
thoroughly, and after a few minutes, the wine should be carefully
smelled. One treatment is often enough, but a second or even a third
treatment may be necessary for difficult cases. The wine should be left
undisturbed for several days after treatment so the copper sulfide (a
very fine black powder) will settle to the bottom of the container.
Then the wine should be carefully racked off the copper sulfide residue.

The following rules should be observed when using copper to remove
hydrogen sulfide odors from wine. (1) Never add copper to active
fermentations. Copper sulfate added during fermentation may cause more
hydrogen sulfide to be formed. (2) Only very small quantities of copper
sulfate solution are required, so use a pipette and measure carefully.
(3) Add the 1% copper sulfate in small (0.1 ppm) doses rather than a
single large dose. Very little copper will remain in the wine when
copper sulfate is used in this way. More copper can be added if needed,
but excessive amounts of copper are difficult to remove from wine. (4)
Never add more than 0.5 ppm of copper to any wine.

Lum
Del Mar, California, USA


IN AUGUST 2006, LUM ALSO POSTED:

Winemakers use one percent copper sulfate solutions ( 1 gram copper
sulfate in 99 milliliters of water) to remove H2S and mercaptan stench
from wine.

The reaction is very quick. Put 50 ml or wine in a glass, add a drop of
1% solution and stir. If the stench does not disappear, it is _not_ H2S
or mercaptan. More info here
http://www.sdaws.org/Articles/Article4.htm


FOR DISULFIDE TREATMENT, LUM POSTED IN AUGUST 2006:

The "third structure" is disulfide.

H2S is a stinky gas. If the H2S is not removed from the wine in a few
weeks, the H2S will react with alcohol in the wine and form mercaptan.
If the wine containing mercaptan is aerated, the mercaptan will form
disulfide. H2S and mercaptan will react with copper and form copper
sulfide. Copper sulfide is a solid. It has no odor and it precipitates
out of the wine.
Unfortunately, copper will not react with disulfide directly. But,
ascorbic acid (vitamin "C") is sometimes added to wines containing
disulfide. The ascorbic acid breaks the disulfide bond and converts the
disulfide back into mercaptan. Then the mercaptan can be removed with
copper.

BUT, the ascorbic acid-disulfide reaction time is very slow (months not
weeks). So, treating a wine containing disulfide can be a very
frustrating process and many winemakers give up too soon.

"Frank Bacon" > wrote in message
. ..
>I fermented two batches of wine from Sauvignon Blanc grapes in September
>using two different type of yeast, one dry and one semi dry. The dry batch
>still reeks of Hydrogen Sulfide after repeated rackings. I used isinglass
>in the wine and its crystal clear but still smells like rotten eggs! Is
>there anything I can do to get rid of the foul odor? Will is dissipate
>with time?

Hydrogen sulfide should be removed as soon as fermentation is finished
Frank. Check the info here http://www.sdaws.org/Articles/Article4.htm