OFD142014

Green Distillate

16 posts in this topic

Hello,

I am writing to ask if anyone has experienced green distillate before? It isn't blue, more of an emerald green. I first noticed it when rectifying brandy low wines. Then I noticed it again when rectifying sorghum low wines. It does clear up eventually in both instances, however it goes further into my hearts than I am comfortable with. I do supplement the ferments with nutrients rich in Nitrogen. Could excess nitrogen be creating an environment that is oxidizing my copper? It is my understanding that this leads to a blue tint. On stripping runs, I collect down to between 20-40 proof. Is this too low; am I leaving some residue on the inside of my column and or condenser- Is this getting dissolved by the heads/hearts fraction of the spirit run? I am experiencing this in both, the production still and my pilot still which leads me to believe it is something in the wash carrying over and not something in the stills. Is it possible that it is a combination of yellow tailsy residue from the still and bluish oxidation from the copper (yellow+blue=green)? Have any of you experienced this or anything similar? Any help is greatly appreciated.

Thank you,

Emerald City

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Well, at least the color matches your name. Some copper salts are green (just ask Lady Liberty). My first guess would be Cu4SO4(OH)6. Given that its coming through to your distillate, it's probably forming in the condenser. What kind of system are you running? I would recommend doing a through clean of your system and seeing if the problem persists, as the most likely cause is a build-up in your condenser. Could have been caused by a puking run that wasn't fully cleaned. Could also be that you are not fully draining the condenser at the end of the run and the last bit of distillate is sitting in it oxidizing away between runs, leaving plenty of colorful goodies for the next run.

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Keep in mind that the perceived color can be impacted by the lighting, so it wouldn't be a bad bet to assume anything in the bluish/greenish family is going to trace back to the copper. I wouldn't make too much of the color difference.

What are you using to clean the still?

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Ha, I made the name to match the color of my spirit. Thank you all for the information. Our current production still is a copper reflux (copper condenser). The pilot still is a stainless reflux with copper plates (stainless condenser). I flush both stills with hot water after runs, nothing fancy. Every so often, I will use a mild caustic solution followed by mild acid solution as well. Of course I flush after this with hot water back to neutral. Maybe I am not actually cleaning enough? The copper salt formation sounds reasonable to me, but why all of the sudden? We have been operational for almost two years and haven't had this issue until very recently (started last month).

I don't see any blue or green in the cloudy low wines. Maybe it is forming during the strip in the copper system and when being rectified (production or pilot still) it concentrates and makes itself visible? Can this salt, if that be the guilty party, travel up the column as a vapor and then be re-condensed? As I said before, the condenser on the pilot still is stainless and only the plates in the column are copper.

In any case, I will try a thorough cleaning of both stills before rectifying my next brandy and see if this solves the issue. Thanks again!

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Distilling wine, I would worry about copper acetate in a copper condenser forming from any residual acetic acid. But that is a dark teal blue, more than a green. In any case, get rid of the copper condenser.

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The closest I have seen to your experiece was a yellow-green heads stream in a continuous neutral spirit plant. The plant wisdom was that this was diacetyl (butanedione). In this plant the fermenters were steel, the stripper column mostly copper and the rectifier fully stainless steel.

I would be surprised if a colored copper salt could make it to the top of your column, unless you have significant liquid entrainment up the column. If it is a salt it would have to be formed in the final condenser, but the fact that your pilot condenser is SS tends to rule out that theory.

My opinion is that it would have to be formed during fermentation. Did you make any changes in the fermentation temperature or agitation or nutrients that coincided with the appearance of this problem?

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I would be surprised if a colored copper salt could make it to the top of your column, unless you have significant liquid entrainment up the column. If it is a salt it would have to be formed in the final condenser, but the fact that your pilot condenser is SS tends to rule out that theory.

It wasn't clear to me that he was seeing this using a SS condenser. OFD, could you clarify?

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Again, thank you all for the information. Just to clarify, I do the stripping runs in the 100% copper still. From there, the low wines get put back into the copper still for rectification if it is a product we intend to sell. If the low wines are intended for RnD, they go into the stainless pilot still. I am leaning towards something formed either in fermentation or in the copper condenser. I suppose the green isn't visible in the cloudy low wines until it is concentrated in the rec-run? I have been assembling my own "nutrient bomb" as of late that might be contributing to this in the wine and sorghum distillations that I am seeing this in. Problem is, the color hasn't reared its head in any of the other products that I am making... using the same basic set of nutrients. Nutrient Bomb for my 300 gallon ferment: 3 cups DAP, 1 cup boiled (deceased) yeast, 1/4 cup thiamine hydrochloride, 1/8 cup magnesium sulfate. Am I too high on any of these? Could too much DAP be causing this? Temps, agitation, etc. have remained the same. I did not use this "bomb" on the brandy wash, I used bio-ferm complete. I ran the brandy first, noticed the green color, then when done ran the sorghum... heads came with green color. Maybe it's something residual from the brandy (acetic, diacetyl?) that didn't get washed out before running the sorghum. Even after rerunning this colored spirit, it still comes out with the same color green heads smearing into the hearts.

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Clarification I sought was: do you see color when using a stainless steel condenser, not still?

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Apologies, bluestar. The short answer is yes, I do see the green color in the stainless condenser. The stainless condenser is attached to the stainless pilot still. The copper condenser is attached to the copper production still. No wash goes directly into the pilot still without first being stripped by the copper production still. Could the distillate be picking this color up during the stripping run in the copper still/condenser? I don't see the low wines to be green in their cloudy, low proof state. Maybe the color is diluted so much that I cant see it? Could it be that the low wines from the stripping run are so low proof, and smeared that the reaction doesn't occur there? Perhaps the reaction only occurs during the rectification run, when the fractions are more concentrated? What are your thoughts?

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OK, assuming you are cleaning your SS still properly, you should not be seeing any carry over of copper salts from a redistillation in the SS after stripping in the copper still. I would test that green stuff to determine what it is. What kind of gaskets do you have in the vapor path in the SS still?

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Fair enough, I was planning on getting it tested just for my peace of mind. I am using plain old silicon gaskets.

Silicone should not be a problem, EPDM for example should be avoided, can get leachate in the spirit.

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Copper carbonate? It's green. You said you use soda ash, right? Maybe residual soda ash, not complete neutralized by the citric or rinsed out by the hot water reacting with the copper condenser.

Have also heard of excessively gassy (CO2) charges can also cause lime green distillates.

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I have experienced the same anomaly... yellowish/greenish tint to my first stripping run of apple brandy... although mine has not cleared after almost 2 weeks sitting in the collection glass carboy... please see my post on this topic... 

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