Running Grape Wine - Pot Still vs. Crystal Dragon - Something isn't right

JoeHell

Is there a scientific explanation why a 4" Crystal Dragon would turn a decent rose' wine into "poison" yet a pot still setup produced a more neutral spirit? When using the dragon the first gallon or so of product had a very intense and distinct sulfur dioxide gas characteristic...one whiff would literally take your breath away to which you could feel for several minutes. I wouldn't think due to the age of the wine that there would be too much SO2 left.

After a very short period of time we shut everything down and came back to it the next day. At that point we disassembled the dragon and rebuilt as a pot still. The resulting product had a much more neutral and far from offensive odor...dare I say palatable.

Previous runs with already stripped wine produced different results but it was equally as bad. In that case the first product to come off had a faint yellow color to it and also left a brownish residue in the pot and on the glass.

All of the equipment was carefully scrubbed and several cleaning runs were made just to get a feel of things several months prior to any other use.

Smaug

Sounds like a more compressed fore shot and heads than you are used to dealing with.

Patina on the copper or a bright virgin finish? Cleaning run with alcohol?

TheMechWarrior

Hi @JoeHell,

A couple of observations:

1. The yellow colour you observed is often seen during a cleaning run on new copper, at least it was for me.
2. The fores from a wine run are atrocious. I've run (20+yo wine) Pinot and Chardonnay and both fores will strip the hairs from your nose, be careful.
3. The pot gets a brown deposit meaning you need to manually clean the pot and the elements after each run.
4. Your plates foul up and your copper structured packing will turn black, you need more frequent cleaning when processing wine compared to a grain/sugar wash.
5. I ran 5 plates plus a packed section for both stripping and spirit run. No RC and high power for the strip. RC on and lower power for the spirit run.
6. The only reason I could think of for the CD producing a flavour taint would be the quality of the copper, the yellow spirit suggests to me the unit was not clean at the start?
7. The hearts of a wine run a very delicious, I love the fruity aroma. They make great brandy.
8. Try the CD again. Do a vinegar cleaning run and TPW sacrificial run first though, just be sure.

Kapea

Sounds like the winemaker overdid the sodium metabisulfite dosing to me.

JoeHell

@Kapea said: Sounds like the winemaker overdid the sodium metabisulfite dosing to me.

The wine had 25 ppm SO2 at bottling over 3 years ago...a low amount to start with.

JoeHell

@Smaug said: Sounds like a more compressed fore shot and heads than you are used to dealing with.

Patina on the copper or a bright virgin finish? Cleaning run with alcohol?

There were cleaning runs with vinegar and separate runs with alcohol. Everything so far has been disposable so to speak, just to get a feel for things. Additionally the copper was cleaned by itself just prior to use.

JoeHell

@TheMechWarrior said: Hi JoeHell,

A couple of observations:

1. The yellow colour you observed is often seen during a cleaning run on new copper, at least it was for me.

2. The fores from a wine run are atrocious. I've run (20+yo wine) Pinot and Chardonnay and both fores will strip the hairs from your nose, be careful.

3. The pot gets a brown deposit meaning you need to manually clean the pot and the elements after each run.

4. Your plates foul up and your copper structured packing will turn black, you need more frequent cleaning when processing wine compared to a grain/sugar wash.

5. I ran 5 plates plus a packed section for both stripping and spirit run. No RC and high power for the strip. RC on and lower power for the spirit run.

6. The only reason I could think of for the CD producing a flavour taint would be the quality of the copper, the yellow spirit suggests to me the unit was not clean at the start?

7. The hearts of a wine run a very delicious, I love the fruity aroma. They make great brandy.

8. Try the CD again. Do a vinegar cleaning run and TPW sacrificial run first though, just be sure.

1-4 is spot on to what I have run into thus far. The hearts were great. Very floral with notes of Anise and Coffee

grim

There is no place a sulfur compound could come, but from but the wine. There would be a number of different sulfur components, many concentrated in the heads, but likely prevalent through the run.

@JoeHell said: After a very short period of time we shut everything down and came back to it the next day. At that point we disassembled the dragon and rebuilt as a pot still. The resulting product had a much more neutral and far from offensive odor...dare I say palatable.

Am I understanding this correctly - you stopped mid run, left the boiler contents in place, and the next day replaced the plates with the pot head and continued the distillation?

If so, you may have already stripped most of the volatile sulfur compounds off in the fractions taken with the plates, if you reran the remainder with the pot head, it's likely you would have just smeared the smaller remaining volume of sulfur compounds over the run, maybe pushing them below detection.

I've seen plenty of seemingly innocuous, passable wines turn into absolute stink bombs on the still.

Any chance you have any idea of the volatile acidity of the wine? Is this a fault wine you are distilling? High levels of volatile acidity in the wine can be overly aggressive to the copper, as can the metabisulfite and acetaldehyde.

grim

See page 240 in this (PDF) document:

The heads fraction may be highly acidic and corrosive if sulfur dioxide or bisulfite is used in the production or preservation of the wine. The reversible reactions involved are:

H 2 0 + S0 2 HSO3- + H+

HSO3 - + CH3CH O CH3CHOHSO3-

The acetaldehyde—sulfurous acid compound has the properties of a sulfonic acid with C—S linkage rather than an ester structure as once assumed. It is properly 1-hydroxyethane sulfonic acid (23, 24) and is highly acidic (25). Samples of concentrated heads from commercial aldehyde columns having aldehyde contents of 5-13% gave p H values of 0.7-0.9 and contained high levels of copper (25).

Whitmore (26) and Deibner and Bénard (27) claim that sulfonic acids are capable of distilling intact. However, it would seem more likely that at the temperature of the distilling process, 1-hydroxyethane sulfonic acid in the wine would dissociate into the very volatile free acetaldehyde and therefore rapidly distill along with free sulfur dioxide and recombine at the top level of the fractionating column.

JoeHell

@grim said: There is no place a sulfur compound could come, but from but the wine. There would be a number of different sulfur components, many concentrated in the heads, but likely prevalent through the run.

Any chance you have any idea of the volatile acidity of the wine? Is this a fault wine you are distilling? High levels of volatile acidity in the wine can be overly aggressive to the copper, as can the metabisulfite and acetaldehyde.

I don't have any records that I can find of the acidity. I wouldn't call it a fault wine more than an overabundance of cased goods. The wine itself is a 2011 Rose'. The wine has a great nose but is a tad bitter on the palate with little to no finish.

JoeHell

You are correct that I stopped mid-run. I assumed that I may have just extracted the bad on day one and was left with the "good stuff" the following day. I guess my main apprehension the first day came because it was such a stark contrast to anything I had run before it.

TheMechWarrior

You are correct, the crap comes off first, so day 1 was the worst of it. When I said the fores were bad, I was down playing just how truly bad they are. But you already know this ;)

Ryan

If your fermented mash as any hint of "rotten egg" (H2S) smell it going to concentrate in your fores. H2S is obviously very potent and the human nose can sense very low concentrations.

Instead of relying on bare copper in your still to knock out the H2S you can simply treat your fermented mash with copper sulfate the day before and it will drop out (precipitate) the H2S. You really don't need much. See here: How to Solve "Rotten Egg" Smell in Wine

Better link: Treatment for Removal of H2S

TheMechWarrior

Now I wish I still had some of that old wine to try this on! What an intriguing find, thanks for sharing.

jacksonbrown

I visited an award winning single malt joint here and noted how blue his low wines tank was. At the time I remember thinking his still must be corroding bloody quick but maybe this was one of his secrets. He came from a chem background from memory.

TheMechWarrior

I've seen blue low wines before, it came from too much nutrient and or too high a power on the still. Both variables were dropped back and the blue went away.

brewsmith

Does anyone know what the blue compound is called in that reaction with copper?

Kapea

Cuprammonium hydroxide.

Ryan

@TheMechWarrior said: I've seen blue low wines before, it came from too much nutrient and or too high a power on the still. Both variables were dropped back and the blue went away.

It's usually an indication that your fermented mash pH is too high and ammonia is dropping out (from the N2 compounds like amino acids and other nutrients). Then the ammonia combines with water to make ammonium hydroxide which strips the copper off your still turning your low wines blue-ish (cupric hydroxide).

You might already know this, but the fermented mash should be acidic whereas subsequent low wines can be basic (or buffered) Low wines will not contain any N2 compounds to form ammonia so if your desire is to minimize ester formation (especially if your goal is a neutral spirit) buffer your low wines.

TheMechWarrior

Ta, I explained all that to the chap with the blue spirit and he cut back the nutrients, monitored his pH and adjusted his still operation.

grim

Low wines will not contain any N2 compounds to form ammonia so if your desire is to minimize ester formation (especially if your goal is a neutral spirit) buffer your low wines.

One of my favorite topics - reducing the acidity of the low-wines will shift the equilibrium point of Fischer esterification towards lower, rather than greater ester production.

jacksonbrown

The guy I referred to was making internationally acclaimed single malt so I don't think he saw it as a fault to be rectified.
So if the desire is to maximise ester formation in a heavy rum for example, I should throw a hand full of lime into my low wines tank? Is there a target pH?

Grim have you got stuff on sale? I think I need to taste the fruits of your labors. Neutral was a bit of a no brainer for me but aged brown spirit where the magic is. That goes for a quite a few of you actually. I'd really like to taste what you guys are proud to be producing. I'll happily pay postage and handling on 20ml samples if the selling of product is an issue.

JoeHell

@Ryan said: If your fermented mash as any hint of "rotten egg" (H2S) smell it going to concentrate in your fores. H2S is obviously very potent and the human nose can sense very low concentrations.

Instead of relying on bare copper in your still to knock out the H2S you can simply treat your fermented mash with copper sulfate the day before and it will drop out (precipitate) the H2S. You really don't need much. See here: How to Solve "Rotten Egg" Smell in Wine

Better link: Treatment for Removal of H2S

There was no noticeable reduction or H2S to any of the product prior to distillation but man that was some stinky tail! LOL. It was so bad the dog wouldn't even take the blame.