Distillation of sulfur dioxide containing ingredients

[Brewstilla]

We are starting some R&D on a product that involves the redistillation of a base spirit with other ingredients, including some fruit. For ease, consistency, and fruits not available in our locale, I would like to use dried fruits. After some research, it seems the vast majority are packaged with SO2. 

So my question is, will the SO2 come over in the spirit like many other sulfur compounds? I am guessing that this will be the case, and is easy enough for me to trial on the benchtop still, but figured I would throw it out here first to see if anyone had any experience or input before doing that.

Thanks! 

[Silk City Distillers]

Sulfur dioxide will come over, you will need to treat.

https://onlinelibrary.wiley.com/doi/full/10.1002/jib.100

[PeteB]

I did some very interesting distillation of sulfured wine a couple of months ago.

Some bulk wine was double distilled at another distillery using simple pot still. The sulfur fumes on the first run were very strong. Calculated additions of H2O2 were made during the run to help knock it out. More H2O2 was added during the spirit run.

I did the stripping run of my share of the wine through my continuous copper stripping column. No H2O2 added. Very surprisingly there was no sulfur smell and a test of the sulfur level in the low wines was low. We did add some H2O2 during the spirit run to clean it up a bit more.

The hot feed wine splashes down over copper plates, and vapors move up over the plates in the stripping column. Maybe the sulfur in the hot liquid feed wine reacts much better with the copper. In a regular pot still the sulfur/copper contact would mainly be vapor.

 

 

[meerkat]

I think @PeteB is correct regarding the reactions being faster in the liquid phase.  I have seen large continuous vodka columns which were made of stainless steel, but the reflux was passed through a bed of copper raschig rings before returning to the column.

Edited November 17, 2020 by meerkat
typo

[PeteB]

I did read somewhere, possibly on this forum many years ago, that silicon based antifoam will coat the copper surface and reduce interaction with sulfur !!

Does anyone know if this is true?

[JustAndy]

My experience with antifoam is that it fouls the still much easier than normal; the coagulated muck it creates cooks onto the hot copper and it makes sense that this forms a physical barrier which reduces copper interaction.  

The level of so2 allowed in dried fruit is something like an order of magnitude greater than is typical in wine, but I think whether it's a problem in redistillation will really depend on how much you use. 

[Storm King Distilling Co.]

Guys, I just finished distilling a bunch of wine that had way more sulfur dioxide than we thought. The distillate tastes great, but the smell is super pungent. We knew it was coming over in the distillate when I almost got knocked out by it sniffing the samples prior to the heads cut. We thought maybe it would dissipate as the finished spirit sat in stainless, but that is not happening. So the question is can we treat the brandy prior to barreling and proofing with anything that can help us? I read the report that @Silk City Distillersposted a year ago and it seems as though we might be able to add Activated Charcoal but then I think we'd have to distill it again, which I am trying to avoid. I was thinking adding the charcoal then letting it sit around, filtering, and then barreling in a charred barrel. Thoughts?....Another thought will a char 4 over 5 years do the trick on its own? next time we will do the treatment before any of the distillation, but we just didnt think the sulfur was as high as it obviously was. Cheers!

[kleclerc77]

30 minutes ago, Storm King Distilling Co. said:

....Another thought will a char 4 over 5 years do the trick on its own? next time we will do the treatment before any of the distillation, but we just didnt think the sulfur was as high as it obviously was. Cheers!

I'd be hesitant to put fruit distillate into new charred American oak, especially a 4 char - it just doesn't stand up (in my opinion!!!). I would try to clean it up beforehand. Like @meerkat and @PeteBpointed out, copper contact with liquid can help reduce sulfur a lot. If you don't want to redistill it - any way to gently agitate for a while in your still or a vessel with a bunch of copper?

[Silk City Distillers]

Take a stroll through the literature on Copper Sulfate Pentahydrate treatment in wine as well, it might be effective for you, but you'll need to redistill.  It's the equivalent of forcing copper reactions chemically.  You can use more than they do in wine, but again, you MUST decant the distillate off any precipitate and redistill, Copper Sulfate Pentahydrate is poison in the amounts you'll need to treat low/high wines.

https://vinlab.com/wp-content/uploads/2017/03/Vinlab-Copper-Trial-and-Addition.pdf

It's a much more targeted approach than carbon, which is just a sledgehammer in this situation.

[Storm King Distilling Co.]

Cheers @kleclerc77 and @Silk City Distillers we shall see. This all seems like a distraction from whiskey making. Right now I am just blaming my brother-in-law for adding sulfur to his wine after I told him not to. 

[JustAndy]

7 hours ago, Silk City Distillers said:

Take a stroll through the literature on Copper Sulfate Pentahydrate treatment in wine as well, it might be effective for you, but you'll need to redistill.  It's the equivalent of forcing copper reactions chemically.  You can use more than they do in wine, but again, you MUST decant the distillate off any precipitate and redistill, Copper Sulfate Pentahydrate is poison in the amounts you'll need to treat low/high wines.

https://vinlab.com/wp-content/uploads/2017/03/Vinlab-Copper-Trial-and-Addition.pdf

It's a much more targeted approach than carbon, which is just a sledgehammer in this situation.

I believe copper treatment is used for reductive aromas / sulfides and won't address sulfur dioxide issues.  To me treating the distillate with hydrogen peroxide and redistilling is the best course. A portion of the so2 aroma will dissipate over the course of aging, but the distillate usually retains a detectable plastic / rubber / chemical aroma. You might think the spirit tastes great but if there is so much so2 that you can't nose it, it's very difficult to make correct cuts during the distillation and although the so2 will dissipate with aging incorrect cuts sometimes are not fixed by time. 

[Silk City Distillers]

Yeah, understood.  I was under the impression that brandies distilled from wines with sulfur dioxide often saw h2s and other sulfides formed from so2.

[JustAndy]

@Silk City Distillersthere might technically be some connection but in my experience they are separate issues. There is some aspect of co-morbidity as just about all wine sent for distillation has too much so2 and wine-makers often aren't aware its an issue. But excess sulfide IS an issue wine-makers notice and sends some of them down the distillation path. Sometimes copper contact from double or triple distillation is enough to resolve sulfide issues but I think it depends on what form it is in and the distillate often has a baseline meaty/savory character. I do a fair bit (let say a small volume but wide variety) of contract wine distillation and after 9 years I am coming close to having encountered everything that can go wrong with a wine.  

[Storm King Distilling Co.]

@JustAndy cheers, I think the peroxide approach is worth a shot and see what happens.