Using copper to reduce sulfur - cider in IBCs
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Matt Cavers
May 17, 2016, 1:17:45 AM5/17/16
to Cider Workshop
Hi everyone,
I've got two ~950 L batches of cider right now that show a pronounced H2S aroma. The sulfur smell wasn't apparent at the end of fermentation - about two weeks ago - but since then has become just a shade too strong for me to comfortably ignore. I've tried to blow off the H2S by racking vigorously and bubbling CO2 through a diffusion stone, but to no avail.
I'm weighing the pros and cons of treating the two batches with copper. From what I've read on this forum, it seems that when copper sulfate is used to eliminate H2S, the cider is racked off the resultant copper salts soon afterward. Two questions come to mind (assuming copper works to reduce the H2S in my particular batches of cider), and maybe there are cider makers out there who could answer them...?
- Is it necessary to rack within a day or two of treatment with copper sulfate, or could I delay by a month or two? Having just racked the cider (splashily, into CO2-purged IBCs) off the gross lees, it's still quite hazy with suspended yeast, and I'd sure like to see it drop clear before I bother to move it again. I'd be happiest if the cider's next move was into a bright tank for carbonation and dry-hopping!
- As you can see from the above question, I'm using IBCs as fermenters and storage tanks. Having no standpipe in the containers, I don't have a way of fully excluding the lees when transferring the cider, though I'll attempt to minimize this by tilting the containers slightly backward when pumping out. And - important bit - I don't have filtration equipment. If the resultant cupric sulfide (do I have this right?) is toxic, will I be simply transporting toxic salts from IBC to bright tank to keg - and to glass? This seems like something I ought to avoid.
On the other hand, does anyone have any experience reducing sulfur smells simply by stirring their cider with copper? I do have a long copper coil I could brighten up and sanitize and gently stir with.
Many thanks for your input.
Matt Cavers
I've got two ~950 L batches of cider right now that show a pronounced H2S aroma. The sulfur smell wasn't apparent at the end of fermentation - about two weeks ago - but since then has become just a shade too strong for me to comfortably ignore. I've tried to blow off the H2S by racking vigorously and bubbling CO2 through a diffusion stone, but to no avail.
I'm weighing the pros and cons of treating the two batches with copper. From what I've read on this forum, it seems that when copper sulfate is used to eliminate H2S, the cider is racked off the resultant copper salts soon afterward. Two questions come to mind (assuming copper works to reduce the H2S in my particular batches of cider), and maybe there are cider makers out there who could answer them...?
- Is it necessary to rack within a day or two of treatment with copper sulfate, or could I delay by a month or two? Having just racked the cider (splashily, into CO2-purged IBCs) off the gross lees, it's still quite hazy with suspended yeast, and I'd sure like to see it drop clear before I bother to move it again. I'd be happiest if the cider's next move was into a bright tank for carbonation and dry-hopping!
- As you can see from the above question, I'm using IBCs as fermenters and storage tanks. Having no standpipe in the containers, I don't have a way of fully excluding the lees when transferring the cider, though I'll attempt to minimize this by tilting the containers slightly backward when pumping out. And - important bit - I don't have filtration equipment. If the resultant cupric sulfide (do I have this right?) is toxic, will I be simply transporting toxic salts from IBC to bright tank to keg - and to glass? This seems like something I ought to avoid.
On the other hand, does anyone have any experience reducing sulfur smells simply by stirring their cider with copper? I do have a long copper coil I could brighten up and sanitize and gently stir with.
Many thanks for your input.
Matt Cavers
Dick Dunn
May 17, 2016, 2:26:56 AM5/17/16
to cider-w...@googlegroups.com
snipping out some bits, and interspersing replies to various questions,
below:
On Mon, May 16, 2016 at 10:17:44PM -0700, Matt Cavers wrote:
> I've got two ~950 L batches of cider right now that show a pronounced H2S
> aroma. The sulfur smell wasn't apparent at the end of fermentation - about
> two weeks ago - but since then has become just a shade too strong for me to
> comfortably ignore...
What's your total fermentation period? Point of question: Would a bit of
time tame it down, or have you already given it enough that it should have
come right?
> I'm weighing the pros and cons of treating the two batches with copper.
> >From what I've read on this forum, it seems that when copper sulfate is
> used to eliminate H2S, the cider is racked off the resultant copper salts
> soon afterward...
Well...yes, the cider is racked off the insoluble copper sulfide, but let's
be careful about the meaning of "soon".
> - Is it necessary to rack within a day or two of treatment with copper
> sulfate, or could I delay by a month or two? Having just racked the cider
> (splashily, into CO2-purged IBCs) off the gross lees, it's still quite hazy
> with suspended yeast, and I'd sure like to see it drop clear before I
> bother to move it again...
Let's go for a point between "a day or two" and "a month or two". Since
you're wanting the CuSO4 to have time to act, and then get the insoluble
sulfide to drop out, you do need to give it "some time". Give it a week
and see what's going on. If the cider is still turbid it might mean you've
still got some sulfide which hasn't settled out. OTOH you shouldn't need a
month or two, and might not want to wait that long, to avoid other adverse
changes. Regard the copper treatment and racking as one process, where you
do the treatment and then wait a period of time proper to finishing the
treatment for a racking.
>...I'd be happiest if the cider's next move was into
good cider, why are you going to spoil it by adding hops?
(OK, never mind, I know the answer:-(
To the point: If you're going to add hops at the end for whatever reason,
that's going to give you material which will need to settle out. Hopping
in a bright tank isn't so bright.
> - As you can see from the above question, I'm using IBCs as fermenters and
> storage tanks. Having no standpipe in the containers, I don't have a way of
> fully excluding the lees when transferring the cider, though I'll attempt
> to minimize this by tilting the containers slightly backward when pumping
> out. And - important bit - I don't have filtration equipment. If the
> resultant cupric sulfide (do I have this right?) is toxic, will I be simply
> transporting toxic salts from IBC to bright tank to keg - and to glass?
Not so much toxic as unpleasant, metallic. (Yes, toxic in some sense, but
it's unpleasantly metallic at levels well below toxicity.) Rack it and see
how clean you can keep it; don't be afraid to lose some of the dregs in
order to avoid carrying over what you don't want!
> On the other hand, does anyone have any experience reducing sulfur smells
> simply by stirring their cider with copper? I do have a long copper coil I
> could brighten up and sanitize and gently stir with.
All you're doing with that is replacing an ability to do a measured
treatment with a "winging it" treatment. Stirring with that copper coil
will still create insoluble copper sulfide which you need to rack away
from.
If you do the measured CuSO4 treatment, you know the parameters and you can
get the dosage spot on.
If you wave a wand of copper into the cider, you might get it right...or
you might under-treat and retain a sulfidic note in the cider...or you
might over-treat and end up with harsh-metallic green cider. I've had (and
made) all three. I know which one I want to aim for, and it can only be
done by accuracy.
--
Dick Dunn rc...@talisman.com Hygiene, Colorado USA
below:
On Mon, May 16, 2016 at 10:17:44PM -0700, Matt Cavers wrote:
> I've got two ~950 L batches of cider right now that show a pronounced H2S
> aroma. The sulfur smell wasn't apparent at the end of fermentation - about
> two weeks ago - but since then has become just a shade too strong for me to
What's your total fermentation period? Point of question: Would a bit of
time tame it down, or have you already given it enough that it should have
come right?
> I'm weighing the pros and cons of treating the two batches with copper.
> >From what I've read on this forum, it seems that when copper sulfate is
> used to eliminate H2S, the cider is racked off the resultant copper salts
Well...yes, the cider is racked off the insoluble copper sulfide, but let's
be careful about the meaning of "soon".
> - Is it necessary to rack within a day or two of treatment with copper
> sulfate, or could I delay by a month or two? Having just racked the cider
> (splashily, into CO2-purged IBCs) off the gross lees, it's still quite hazy
> with suspended yeast, and I'd sure like to see it drop clear before I
Let's go for a point between "a day or two" and "a month or two". Since
you're wanting the CuSO4 to have time to act, and then get the insoluble
sulfide to drop out, you do need to give it "some time". Give it a week
and see what's going on. If the cider is still turbid it might mean you've
still got some sulfide which hasn't settled out. OTOH you shouldn't need a
month or two, and might not want to wait that long, to avoid other adverse
changes. Regard the copper treatment and racking as one process, where you
do the treatment and then wait a period of time proper to finishing the
treatment for a racking.
>...I'd be happiest if the cider's next move was into
> a bright tank for carbonation and dry-hopping!
If you're going to the effort of clearing a sulfide taint of a potentially
good cider, why are you going to spoil it by adding hops?
(OK, never mind, I know the answer:-(
To the point: If you're going to add hops at the end for whatever reason,
that's going to give you material which will need to settle out. Hopping
in a bright tank isn't so bright.
> - As you can see from the above question, I'm using IBCs as fermenters and
> storage tanks. Having no standpipe in the containers, I don't have a way of
> fully excluding the lees when transferring the cider, though I'll attempt
> to minimize this by tilting the containers slightly backward when pumping
> out. And - important bit - I don't have filtration equipment. If the
> resultant cupric sulfide (do I have this right?) is toxic, will I be simply
> transporting toxic salts from IBC to bright tank to keg - and to glass?
it's unpleasantly metallic at levels well below toxicity.) Rack it and see
how clean you can keep it; don't be afraid to lose some of the dregs in
order to avoid carrying over what you don't want!
> On the other hand, does anyone have any experience reducing sulfur smells
> simply by stirring their cider with copper? I do have a long copper coil I
> could brighten up and sanitize and gently stir with.
treatment with a "winging it" treatment. Stirring with that copper coil
will still create insoluble copper sulfide which you need to rack away
from.
If you do the measured CuSO4 treatment, you know the parameters and you can
get the dosage spot on.
If you wave a wand of copper into the cider, you might get it right...or
you might under-treat and retain a sulfidic note in the cider...or you
might over-treat and end up with harsh-metallic green cider. I've had (and
made) all three. I know which one I want to aim for, and it can only be
done by accuracy.
--
Dick Dunn rc...@talisman.com Hygiene, Colorado USA
Matt Cavers
May 17, 2016, 12:30:32 PM5/17/16
to Cider Workshop
Hi Dick,
This is tremendously helpful - thanks so much for taking the time to reply.
In answer to your first question, fermentation proceeded pretty rapidly once it began. I pitched yeast into the juice at 15 C, and within 7-9 days, the gravity in each container had dropped from 1.050 to 1.000. The temperature inside the containers climbed to a high of 17 C. I rehydrated the EC-1118 yeast with Go-Ferm, added Fermaid O 24 hours after pitching, oxygenated daily until fermentation was roughly one-third done, and added Fermaid K at that point as well. Approximately 10 days after fermentation finished, and a substantial cake of lees had accumulated, I racked into CO2-purged and sanitized IBCs, leaving most of the lees behind.
So - it's been a month since I pitched. Does it seem premature to you to be considering treating the cider with copper sulfate? This is my first time making cider on this scale, and I don't have an intuitive sense of it yet.
As for the hops - well - can't please everyone, I suppose! I quite like some dry-hopped ciders - to each their own. But let me clarify about the dry-hopping process I'm using. Yes, I'll be racking into one of our bright tanks (I work for a brewery, and will be sharing some equipment), but for the purpose of the cider, I'll fit the tank with a standpipe, making it more of a conditioning tank. The hops will be inside muslin bags, tied off to the carb stone. We use this technique for plenty of our beers, in combination with kieselsol finings, and there's never a problem excluding hop particles from the finished beer.
Another question - when adding copper sulfate solution, should one stir it into the cider (under CO2 blanket)? Or simply pour into the top of the container?
Many thanks again!
This is tremendously helpful - thanks so much for taking the time to reply.
In answer to your first question, fermentation proceeded pretty rapidly once it began. I pitched yeast into the juice at 15 C, and within 7-9 days, the gravity in each container had dropped from 1.050 to 1.000. The temperature inside the containers climbed to a high of 17 C. I rehydrated the EC-1118 yeast with Go-Ferm, added Fermaid O 24 hours after pitching, oxygenated daily until fermentation was roughly one-third done, and added Fermaid K at that point as well. Approximately 10 days after fermentation finished, and a substantial cake of lees had accumulated, I racked into CO2-purged and sanitized IBCs, leaving most of the lees behind.
So - it's been a month since I pitched. Does it seem premature to you to be considering treating the cider with copper sulfate? This is my first time making cider on this scale, and I don't have an intuitive sense of it yet.
As for the hops - well - can't please everyone, I suppose! I quite like some dry-hopped ciders - to each their own. But let me clarify about the dry-hopping process I'm using. Yes, I'll be racking into one of our bright tanks (I work for a brewery, and will be sharing some equipment), but for the purpose of the cider, I'll fit the tank with a standpipe, making it more of a conditioning tank. The hops will be inside muslin bags, tied off to the carb stone. We use this technique for plenty of our beers, in combination with kieselsol finings, and there's never a problem excluding hop particles from the finished beer.
Another question - when adding copper sulfate solution, should one stir it into the cider (under CO2 blanket)? Or simply pour into the top of the container?
Many thanks again!
Chris Schmidt
May 17, 2016, 12:45:49 PM5/17/16
to cider-w...@googlegroups.com
Hi Matt;
I had one tote that had a strong-ish sulphur smell to it, so I racked it and hung a single piece of 1/2” copper plumbing elbow in the tote for about two weeks, and no more smell. Cost me $.96 at Home Depot…. I did pick up some of that copper sulfide stuff from BosaGrape, but haven’t had to use it.
Try that and lemme know (offline) if it works!
Brent Klassen
Jan 3, 2017, 3:06:39 PM1/3/17
to Cider Workshop, ch...@todcreekcider.com
Chris -
One of the things I've read about treating H2S with Copper is that it can sacrifice some of the complexity of the end product as the copper will also reduce some of the desirable aromatics in the juice. Was that your experience?
Also, was your tote full? as in, a single copper plumbing elbow dealt with the H2S for 1,000 litres?
Chris Schmidt
Jan 3, 2017, 9:39:17 PM1/3/17
to cider-w...@googlegroups.com
Hi Brent;
That one tote we had was a full 1000L of dessert fruit (MacIntosh if memory serves correct…) that had a mild H2S smell to it. We blended it with other batches of cider once the H2S smell went away for a big batch of 3000L that went into the 16oz cans. I hadn’t received any H2S complaints, and I didn’t notice any smell on the finished batch. We add S02 to about 10-14ppm FSO2 prior to canning and force carbonate to 2ATM. Even with the 2 month fermentation, there really isn’t a lot of ‘complexity’ to the dessert fruit cider to get sacrificed with H2S, so I can’t confirm or deny what you’ve read from my experience other than to say “it worked ok for me".
My lessons from that experience are:
- if you have a hint of H2S, do what Wes/Claude/Andrew suggest and then blend it with other cider that doesn’t have H2S.
- always follow a really good fermentation protocol (yeast nutrients, etc) to prevent it in the first place (since that experience, I haven’t had a recurrence of H2S in the approx 30 x 1000L batches we’ve produced). We use Go-Ferm and Ferm-O with our EC-1118 yeast, and only a wee bit of Ferm-O when we’re doing wild ferment cider.
- blending the cider with some crabapple & bittersweet (Tremlett and Dabinett are my main two varieties of Bittersweet) really do a great job of adding complexity if you have cider that has lost, or never had, its complexity. Same thing with making some wild ferment cider that you can use to add really neat flavours to otherwise ho-hum cider.
And yes, single 1/2” copper fitting for a 1000L tote….best 99 cents I ever spent! :)
Cheers!
Wes Cherry
Jan 4, 2017, 1:52:22 PM1/4/17
to cider-w...@googlegroups.com
Chris,
What did the test results show for the residual copper levels in your cider? The legal limit is 0.5ppm in the US. Not sure what it is in Canada.
ETS labs charges $29 for a copper test.
It would be cheaper to add a known amount of copper via copper sulfate solution. A 32 oz container of 10% costs $22.55 from All World (smaller sizes and 1% also avail). That’s enough to dose 472,500 liters at a typical dose of 0.2ppm, or 5c per 1000 liters
I suppose one could add a controlled amount of copper with a bit of plumbing by periodically weighing the copper piece. 0.2 ppm would correspond to 0.2g mass loss in 1000L.
Ideally one has done trials to determine the absolute minimum copper to add. Then it should settle out as insoluble CuS in the lees.
You can purchase a testing kit here
Copper is a neurotoxin, immunosuppressant,, and is also toxic to the liver and kidneys. Oddly, the US limit for drinking water is 1.3ppm, while wine and cider can only have 0.5ppm!
-Wes
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Dick Dunn
Jan 4, 2017, 5:33:01 PM1/4/17
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On Wed, Jan 04, 2017 at 10:52:15AM -0800, Wes Cherry noted:
...
> It would be cheaper to add a known amount of copper via copper sulfate solution. A 32 oz container of 10% costs $22.55 from All World (smaller sizes and 1% also avail). That???s enough to dose 472,500 liters at a typical dose of 0.2ppm, or 5c per 1000 liters
>
> http://www.wine-testing-supplies.com/Category/copper-sulfate-from-aws <http://www.wine-testing-supplies.com/Category/copper-sulfate-from-aws>
Wes - This doesn't seem to say anything about the "grade" (purity) of the
copper sulfate, at least not that I can find.
For myself, with some combination of paranoia and ignorance, I'd want to
know that I had a real "reagent" grade. I didn't when I was dosing my own
home cider, but for commercial use I did.
I guess the argument against my viewpoint is that the CuSO4 is used in such
a tiny quantity, and even in a technical grade the impurities would be a
such a tiny fraction of that, that it could hardly matter. Unfortunately,
paranoia doesn't listen very well to reason!
(Of course, the real danger in working with CuSO4 is mis-calculating the
dose by slipping a decimal point--which is quite separate from any question
of purity!)
...
> It would be cheaper to add a known amount of copper via copper sulfate solution. A 32 oz container of 10% costs $22.55 from All World (smaller sizes and 1% also avail). That???s enough to dose 472,500 liters at a typical dose of 0.2ppm, or 5c per 1000 liters
>
> http://www.wine-testing-supplies.com/Category/copper-sulfate-from-aws <http://www.wine-testing-supplies.com/Category/copper-sulfate-from-aws>
Wes - This doesn't seem to say anything about the "grade" (purity) of the
copper sulfate, at least not that I can find.
For myself, with some combination of paranoia and ignorance, I'd want to
know that I had a real "reagent" grade. I didn't when I was dosing my own
home cider, but for commercial use I did.
I guess the argument against my viewpoint is that the CuSO4 is used in such
a tiny quantity, and even in a technical grade the impurities would be a
such a tiny fraction of that, that it could hardly matter. Unfortunately,
paranoia doesn't listen very well to reason!
(Of course, the real danger in working with CuSO4 is mis-calculating the
dose by slipping a decimal point--which is quite separate from any question
of purity!)
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