I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:
I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Sounds great but I've had and treated H2s a couple of times in the past
with quick positive results but this time the wine has a slight musty
odor with a hint of H2s so I figured (I'm not a chemist) that somehow
the main problem has been taken care of but there is some sort of H2s
residue hanging on that may have to be treated in a different way, am I
on the wrong track?
If copper is the way to go I'm more than willing to give it a try also
I will try and find a copy of Winery Technology and Operations as soon
as I post this message.

Thanks,
Rick



Joe Sallustio wrote:
Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:
I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

The yeast not being happy during primary fermentation (high H2S
consistent with the fermentation going reductive) may have led to some
cap spoilage, if it started to dry out at any time during primary
fermentation. Did your primary fermentation go very slowly? That could
explain the mustiness.

Also, leaving the fruit 'skins' in contact with the wine for too long
can add a mustiness to wine. I did this intentionally as experiments in
extreme extended maceration (3 months and 6 months) of zinfandel wine.
The wine was good except for a hint of ethyl acetate (overripe pineapple
smell) after 3 months and the beginning of mustiness caused by the skins
starting to break down (in addition to the ethyl acetate) after 6 months.

Another cause of mustiness would be Brettanomyces contamination.
Brettanomyces spores are everywhere, just waiting for insufficient
sanitation practices in preparing the fermentor to get growing.

The other earthy mustiness I'm familiar with is TCA (trichloroanisole),
also know as 'corked' wine. That has been traditionally associated with
either tainted cork used in bottling, but can also be caused by having
damp wood or cardboard in your 'winery', especially when bleach is used
for sanitation.

All four of these musty smells are the byproducts of different kinds of
fungus.... nature's most efficient decomposers.

Gene



Rick wrote:

Sounds great but I've had and treated H2s a couple of times in the past
with quick positive results but this time the wine has a slight musty
odor with a hint of H2s so I figured (I'm not a chemist) that somehow
the main problem has been taken care of but there is some sort of H2s
residue hanging on that may have to be treated in a different way, am I
on the wrong track?
If copper is the way to go I'm more than willing to give it a try also
I will try and find a copy of Winery Technology and Operations as soon
as I post this message.

Thanks,
Rick



Joe Sallustio wrote:

Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:

I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Assuming for a minute that the problem is solely H2S, then Rick is likely
faced with H2S that has already progressed to mercaptans or worse. Assuming
that is 'simply' H2S, he can try to remedy with copper sulfate - but needs
to be very careful; this is deadly stuff. To treat a small quantity like
that, he will need to measurements of grains - not grams. The Margolit book
is the best guide.

I had a similar problem this last year with some Syrah. I had about 20+
gallons in 4 large carboys (6.5's and one 5) The H2S did not become apparent
until a week or so into secondary. Because it appeared in all but one
carboy, I am still perplexed as to cause (if it was in primary - why
wouldn't it show in all 4 carboys? If in secondary, why in three out of 4?
hmmm). anyway, tried a splashy racking, which reduced it, but didn;t solve
it. I then spent a couple weeks learning about copper sulfate and then
trying it. Too late. I ended dumping all but the one carboy. I now have 5
gallons of wonderful Syrah sitting in a carboy with an oak stave, and regret
the loss of the rest.

Figuring that prevention is better than cure, I've been making as many plans
as I can to avoid this problem this year. Adding 'super food' as well as DAP
during primary; increasing punch downs from twice to three times daily.
Other than that, not sure what else i can do other than monitor daily and
'splashy' rack at the first sniff of problem.

any ideas?



The yeast not being happy during primary fermentation (high H2S consistent
with the fermentation going reductive) may have led to some cap spoilage,
if it started to dry out at any time during primary fermentation. Did
your primary fermentation go very slowly? That could explain the
mustiness.

Also, leaving the fruit 'skins' in contact with the wine for too long can
add a mustiness to wine. I did this intentionally as experiments in
extreme extended maceration (3 months and 6 months) of zinfandel wine. The
wine was good except for a hint of ethyl acetate (overripe pineapple
smell) after 3 months and the beginning of mustiness caused by the skins
starting to break down (in addition to the ethyl acetate) after 6 months.

Another cause of mustiness would be Brettanomyces contamination.
Brettanomyces spores are everywhere, just waiting for insufficient
sanitation practices in preparing the fermentor to get growing.

The other earthy mustiness I'm familiar with is TCA (trichloroanisole),
also know as 'corked' wine. That has been traditionally associated with
either tainted cork used in bottling, but can also be caused by having
damp wood or cardboard in your 'winery', especially when bleach is used
for sanitation.

All four of these musty smells are the byproducts of different kinds of
fungus.... nature's most efficient decomposers.

Gene



Rick wrote:

Sounds great but I've had and treated H2s a couple of times in the past
with quick positive results but this time the wine has a slight musty
odor with a hint of H2s so I figured (I'm not a chemist) that somehow
the main problem has been taken care of but there is some sort of H2s
residue hanging on that may have to be treated in a different way, am I
on the wrong track?
If copper is the way to go I'm more than willing to give it a try also
I will try and find a copy of Winery Technology and Operations as soon
as I post this message.

Thanks,
Rick



Joe Sallustio wrote:

Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:

I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

I've never had this problem, but I've been told that racking through a
short, thin length of copper tubing sometimes works, or drop a small
piece of copper in the wine for a few hours (tied to a string for easy
retrieval). Copper is not a nice thing to have in foodstuffs.

Ric wrote:
Assuming for a minute that the problem is solely H2S, then Rick is likely
faced with H2S that has already progressed to mercaptans or worse. Assuming
that is 'simply' H2S, he can try to remedy with copper sulfate - but needs
to be very careful; this is deadly stuff. To treat a small quantity like
that, he will need to measurements of grains - not grams. The Margolit book
is the best guide.

I had a similar problem this last year with some Syrah. I had about 20+
gallons in 4 large carboys (6.5's and one 5) The H2S did not become apparent
until a week or so into secondary. Because it appeared in all but one
carboy, I am still perplexed as to cause (if it was in primary - why
wouldn't it show in all 4 carboys? If in secondary, why in three out of 4?
hmmm). anyway, tried a splashy racking, which reduced it, but didn;t solve
it. I then spent a couple weeks learning about copper sulfate and then
trying it. Too late. I ended dumping all but the one carboy. I now have 5
gallons of wonderful Syrah sitting in a carboy with an oak stave, and regret
the loss of the rest.

Figuring that prevention is better than cure, I've been making as many plans
as I can to avoid this problem this year. Adding 'super food' as well as DAP
during primary; increasing punch downs from twice to three times daily.
Other than that, not sure what else i can do other than monitor daily and
'splashy' rack at the first sniff of problem.

any ideas?



The yeast not being happy during primary fermentation (high H2S consistent
with the fermentation going reductive) may have led to some cap spoilage,
if it started to dry out at any time during primary fermentation. Did
your primary fermentation go very slowly? That could explain the
mustiness.

Also, leaving the fruit 'skins' in contact with the wine for too long can
add a mustiness to wine. I did this intentionally as experiments in
extreme extended maceration (3 months and 6 months) of zinfandel wine. The
wine was good except for a hint of ethyl acetate (overripe pineapple
smell) after 3 months and the beginning of mustiness caused by the skins
starting to break down (in addition to the ethyl acetate) after 6 months.

Another cause of mustiness would be Brettanomyces contamination.
Brettanomyces spores are everywhere, just waiting for insufficient
sanitation practices in preparing the fermentor to get growing.

The other earthy mustiness I'm familiar with is TCA (trichloroanisole),
also know as 'corked' wine. That has been traditionally associated with
either tainted cork used in bottling, but can also be caused by having
damp wood or cardboard in your 'winery', especially when bleach is used
for sanitation.

All four of these musty smells are the byproducts of different kinds of
fungus.... nature's most efficient decomposers.

Gene



Rick wrote:

Sounds great but I've had and treated H2s a couple of times in the past
with quick positive results but this time the wine has a slight musty
odor with a hint of H2s so I figured (I'm not a chemist) that somehow
the main problem has been taken care of but there is some sort of H2s
residue hanging on that may have to be treated in a different way, am I
on the wrong track?
If copper is the way to go I'm more than willing to give it a try also
I will try and find a copy of Winery Technology and Operations as soon
as I post this message.

Thanks,
Rick



Joe Sallustio wrote:

Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:

I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Figuring that prevention is better than cure, I've been making as many plans
as I can to avoid this problem this year. Adding 'super food' as well as DAP
during primary; increasing punch downs from twice to three times daily.
Other than that, not sure what else i can do other than monitor daily and
'splashy' rack at the first sniff of problem.


Sounds like you have a workable plan, I do that and haven't had issues
recently.

Joe

Thx Joe - your advice is always appreciated.


Sounds like you have a workable plan, I do that and haven't had issues
recently.

Joe

Yes it sounds as if it may be too late but I'm on vacation this week
and would like to try and remedy this asap which will means I will not
get the book in time.

I picked up a 10g container of blue crystals Cupric Sulfate Crystals
CusO45H2O at the local homebrew shop but they didn't have any info on
how to use it and there's no user info on the container so I dug around
the internet and found an article that said (a 0.1% solution added at
about 0.5% ml per gallon will give about 0.3% ppm but do not exceed
..05% copper).

It also read that the copper will settle to the bottom in a black form
but recommended fining with bentonite after racking.

If your comfortable giving me the info on how to come up with this
measurement I'd appreciate it and will most likely do a trial starting
with 1/2 the recommended amount.

Actually I made 3 batches of blackberry 2 using D47 and one with 71B
ending up with 6 gallons each in secondary and all developed H2s most
likely due to the Pot Meta I added before hand to kill off bacteria but
I did aerate and add DAP beforehand and a smaller amount on a daily
basis when stirring, nothing to punch down on this one because I added
the Pot Meta and let set for a couple of days gently stirring twice a
day then extracted the juice which made life a whole lot easier
bypassing all the fluff when transferring from primary.

Also on the sanitary end I've made well over a hinder batches of beer
and about 25 batches of wines and meads knock on wood I never had an
infection problem in the past ( I'm a sanitary nut) but I guess you
never know when the bug will strike, hopefully the slight musty odor
will disappear after treatment or a transfer or two along with some
bulk aging.

Rick




Joe Sallustio wrote:
Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:
I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Yes it sounds as if it may be too late but I'm on vacation this week
and would like to try and remedy this asap which means I will not
get the book in time.

I picked up a 10g container of blue crystals Cupric Sulfate Crystals
CusO45H2O at the local homebrew shop but they didn't have any info on
how to use it and there's no user info on the container so I dug around

the internet and found an article that said (a 0.1% solution added at
about 0.5% ml per gallon will give about 0.3% ppm but do not exceed
..05% copper).


It also read that the copper will settle to the bottom in a black form
but recommended fining with bentonite after racking.


If your comfortable giving me the info on how to come up with this
measurement I'd appreciate it and will most likely do a trial starting
with 1/2 the recommended amount.


Actually I made 3 batches of blackberry 2 using D47 and one with 71B
ending up with 6 gallons each in secondary and all developed H2s most
likely due to the Pot Meta which I added before hand to kill off
bacteria but
I did aerate and add DAP beforehand and a smaller amount on a daily
basis when stirring. The fermentation appeared to go well and nothing
to punch down on this one because I added
the Pot Meta and let set for a couple of days gently stirring twice a
day then extracted the juice which made life a whole lot easier
bypassing all the fluff when transferring from primary.


Also on the sanitary end I've made well over a hundred batches of beer
and about 25 batches of wines and meads knock on wood I never had an
infection problem in the past ( I'm a sanitary nut) but I guess you
never know when the bug will strike, hopefully the slight musty odor
will disappear after treatment or a transfer or two along with some
bulk aging.

Rick



Joe Sallustio wrote:
Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:
I have a large batch of blackberry (18 gallons) that I started in early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help but
can't remember any details.

Rick

Rick,
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
Good luck,
Lum

"Rick" wrote in message
ups.com...
Yes it sounds as if it may be too late but I'm on vacation this week
and would like to try and remedy this asap which will means I will not
get the book in time.

I picked up a 10g container of blue crystals Cupric Sulfate Crystals
CusO45H2O at the local homebrew shop but they didn't have any info on
how to use it and there's no user info on the container so I dug around
the internet and found an article that said (a 0.1% solution added at
about 0.5% ml per gallon will give about 0.3% ppm but do not exceed
.05% copper).

It also read that the copper will settle to the bottom in a black form
but recommended fining with bentonite after racking.

If your comfortable giving me the info on how to come up with this
measurement I'd appreciate it and will most likely do a trial starting
with 1/2 the recommended amount.

Actually I made 3 batches of blackberry 2 using D47 and one with 71B
ending up with 6 gallons each in secondary and all developed H2s most
likely due to the Pot Meta I added before hand to kill off bacteria but
I did aerate and add DAP beforehand and a smaller amount on a daily
basis when stirring, nothing to punch down on this one because I added
the Pot Meta and let set for a couple of days gently stirring twice a
day then extracted the juice which made life a whole lot easier
bypassing all the fluff when transferring from primary.

Also on the sanitary end I've made well over a hinder batches of beer
and about 25 batches of wines and meads knock on wood I never had an
infection problem in the past ( I'm a sanitary nut) but I guess you
never know when the bug will strike, hopefully the slight musty odor
will disappear after treatment or a transfer or two along with some
bulk aging.

Rick




Joe Sallustio wrote:
Not sure how that would help, I think you might want to consider Copper
Sulfate. An old trick to add a little copper to the wine was to rack
it through some copper tubing but you are running out of time if this
has been going on for months. Copper in foodstuffs is considered a
poison at some point so it's nothing to fool around with.

Margalit describes a simple procedure to see if copper sulfate will
work in 'Winery Technology and Operations'; if you can't get a copy of
it Ii can sum it up in a post.

Joe


Rick wrote:
I have a large batch of blackberry (18 gallons) that I started in
early
April of this year which developed H2s in the primary, I splashed
transferred and treated with Bocksin but several months later I can
still notice a slight H2s odor?
Does anyone have a cure for this residual odor, I thought I read
somewhere in the past that treating with Potassium Sorbate may help
but
can't remember any details.

Rick

Lum - two questions;
1. there is a third structure that develops after mercaptans (can;t remember
right now) do you know of such?
2. I was of the understanding (mistaken?) that the Cu sulfate effected only
the H2S - NOT the mercaptan structure, nor the ensuing (above). Is that
wrong?

R


Rick,
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
Good luck,
Lum

Ric,

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.

Lum

"Ric" wrote in message
.. .
Lum - two questions;
1. there is a third structure that develops after mercaptans (can;t
remember
right now) do you know of such?
2. I was of the understanding (mistaken?) that the Cu sulfate effected
only
the H2S - NOT the mercaptan structure, nor the ensuing (above). Is that
wrong?

R


Rick,
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
Good luck,
Lum

Thanks Lum - that helped a lot.

If you're still browsing this thread I have, as always (!) more questions;
Does the disulfide still smell?
Last season, I tried to aerate some stinky merlot, didn;t work, so I treated
with Cu sulfate, per Margalit. Still didnlt work (still rotten egg smell).
After a few weeks, no change, so I dumped it. Assuming it was disulfide, I
am now thinking that possibly I could have treated with ascorbic acid, then
Cu sulfate, and left it a while longer.

dang it - dumped about 35 gallons of wine.



Ric,

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.

Lum

"Ric" wrote in message
.. .
Lum - two questions;
1. there is a third structure that develops after mercaptans (can;t
remember
right now) do you know of such?
2. I was of the understanding (mistaken?) that the Cu sulfate effected
only
the H2S - NOT the mercaptan structure, nor the ensuing (above). Is that
wrong?

R


Rick,
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
Good luck,
Lum

Compound Aroma Threshold (ppb)
__________________________________________________ ___________
Hydrogen Sulfide Rotten Egg 0.9-1.5
Ethanethiol Burnt match 1.1-1.8
Methanethiol Rotten cabbage 1.5
Diethyl Sulfide Rubbery 0.9-1.3
Dimethyl Sulfide Canned Corn 17-25
Diethyl Disulfide Garlic 3.6-4.3
Dimethyl Disulfide Cooked cabbage 9.8-10.2


From: Sulfide Sensory Thresholds and Aroma Descriptions ng/ml ppb.
Produced By Enological Technical Services. St. Helena, CA



Ric wrote:
Thanks Lum - that helped a lot.

If you're still browsing this thread I have, as always (!) more questions;
Does the disulfide still smell?
Last season, I tried to aerate some stinky merlot, didn;t work, so I treated
with Cu sulfate, per Margalit. Still didnlt work (still rotten egg smell).
After a few weeks, no change, so I dumped it. Assuming it was disulfide, I
am now thinking that possibly I could have treated with ascorbic acid, then
Cu sulfate, and left it a while longer.

dang it - dumped about 35 gallons of wine.




Ric,

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.

Lum

"Ric" wrote in message
...

Lum - two questions;
1. there is a third structure that develops after mercaptans (can;t

remember

right now) do you know of such?
2. I was of the understanding (mistaken?) that the Cu sulfate effected

only

the H2S - NOT the mercaptan structure, nor the ensuing (above). Is that
wrong?

R



Rick,
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
Good luck,
Lum