Slow proofing and Saponification, have you had it happen?

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atarijedi
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Slow proofing and Saponification, have you had it happen?

Post by atarijedi »

Greetings all,

I imagine any of you that have done any research into proofing down spirits, before aging, after aging, without any aging, have run into the idea of slow proofing as both a means to prevent saponification, and to prevent the mellowing or stifling of flavours.

I am trying to track down the exact reasons why saponification happens when making spirits, I'm an environmental chemist (analyst) by education/trade, and the reasons why this happens vexes me, considering the stories I have heard. So I thought I would come to this forum, and ask people if they have had it happen, and what exactly they were doing when it happened, and maybe I can track down the specifics of this event. So I have a list of questions I'd like you to answer if you have ever had saponification happen (a soapy taste developed). You can put N/A beside the ones that are not applicable, or just leave them blank, please number them though, so I know what question is being answered.

I figure with these questions, I'll be able to figure out exactly what is happening chemically speaking, in order to trigger a saponification reaction. I already have a hypothesis on post-wood aging saponification, but I need some more scenarios in which it has happened to fully flesh my ideas out, and then I can begin to develop some experiments, and do real world tests. That is where you fine folks come into play.

And just to further define it, saponification is in the most basic explanation, when a fat/oil/lipid is turned into a soap, and so you get a soapy flavour in your spirit. More technically, and specific to our case, it is the base hydrolysis of a fatty acid ester into a fatty acid salt. e.g. Ethyl oleate into Sodium oleate. Technically there are a bunch of different ways this hydrolysis can happen, but realistically, under the conditions we deal with, both pre and post aging (if it's being aged at all), the number of actual ways diminishes a lot. It seems to happen in one of these scenarios, directly out of the still, after proofing down but before aging on wood, after aging on wood but before proofing down, or after aging on wood and proofing down, then with spirits like gin or other botanical infusions, there are a bunch of extra steps as well.

So here are the questions, I know there seem to be a lot, obviously you don't need to answer them all, but if you can answer all the relevant questions to the best of your ability, that'll make things easier. If you can add on to that, like you know the temperature and pH of things when you were doing the thing the question asks, then please add that information as well.

1. What spirit were you trying to make?
2. What ingredients did you use in the mash/wash?
3. What type of water did you use in the mash/wash?
4. Did you use a pot still or column still?
5. Did your distillate have a soapy taste?

If you are making a gin or other botanical infusion, you can jump to question 17.

6. Did you proof down prior to aging?
7. What type of water did you use to proof down?
8. After you aged the spirit, but before proofing it down, did it have a soapy taste?
9. What kind of wood did you use for aging?
10. Was it toasted and charred, just toasted, just charred?
11. Was it a barrel, staves, cubes, chips, spirals?
12. Did it taste soapy after removing it from the aging wood?
13. Did you proof it down after aging on wood?
14. What type of water did you use to proof down after aging?
15. What kind of container did you let the spirit mature in after aging and removing the wood?
16. Did it develop a soapy taste over time as it matured?

17. If you are making a gin/infusion, what botanicals did you use?
18. Did you vapour infuse, or macerate?
19. Did you proof down prior to vapour infusion/maceration?
20. Did it taste soapy after proofing down?
21. What kind of water did you use to proof down?
22. Did you proof down after vapour infusion/maceration?
23. Did it taste soapy after proofing down?
24. What kind of water did you use to proof down?

I thank you for any help you can give me. I will make sure to share what I find out both in this post, and I will also make a new post as well.
Hans Lander
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Re: Slow proofing and Saponification, have you had it happen?

Post by Hans Lander »

Did not happen to me and I am only offering my thoughts since it seems no one else did, but I would just imagine that since Saponification is the "alkaline hydrolysis of an ester", and given that esters are most prevalent in the "heads" of a run... It may be possible that some esters are being retained from what is often discarded in the "heads" in the yield being aged. In addition the PH would have to of-course be a little high.... but I can see the "spirits" sometimes aligning to allow such a process. Would certainly be unmistakable in the final yield... soapy.
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Re: Slow proofing and Saponification, have you had it happen?

Post by LWTCS »

This is a great topic.

I personally have not experienced this as I have not made any AG whiskey. But one of my old customer's whiskey absolutely had a soapy flavor. Not at all pleasant.
Delicate subject matter as how does one truthfully critique a bad whiskey when the whiskey maker is having a measure of success and some of that success has trickled down to me.
So I never really had a chance to discuss the actual protocol out of,,,,,politeness.

Basically a 100% malted corn, pot stilled, aged on new medium char oak (53 gallon) barrels.
I don't have any details beyond that.

Was straight up soapy bath water...
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Re: Slow proofing and Saponification, have you had it happen?

Post by jonnys_spirit »


I already have a hypothesis on post-wood aging saponification, but I need some more scenarios in which it has happened to fully flesh my ideas out, and then I can begin to develop some experiments, and do real world tests. That is where you fine folks come into play.
I have not experienced this yet.

What’s your hypothesis?

Thanks,
-j
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i prefer my mash shaken, not stirred
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stillness
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Re: Slow proofing and Saponification, have you had it happen?

Post by stillness »

Just ran into this last night. Went over to a friend's house and he pulled out a bottle we made 5 years ago. It was an all grain mash (I don't remember grain bill exactly, but mostly 2 row barley, with low ABV maybe 5%).
One slow run on an outdated CM still design. Decent cuts. I remember tasting individual glasses with friends. Cuts by committee. No soap. Didn't hear about soap from the 3 other bottles, but they were gone within the year.

He left it on oak at 60% for 3 years, in glass. When I heard, I told him to take it out for sure. Sat with no oak for another 2 years.
Had some great vanilla and caramel, really deep color, decent mouth, very little nose.. but the finish was all perfume and soap. And it stayed with you. It was undrinkable. Really some of the worst, and I was glad the last of this product was gone from the earth.

Edit:
Sorry, no numbers for questions.
I can't remember if we proofed down or not. But I think we must have a little, cause it was right at 60%, but I don't think the hearts were much above that.
The water for mash and proofing was city water out of the tap. No water was added during oaking/maturing.
The oak was a charred oak dowel from home depot. (Don't judge me world)
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Re: Slow proofing and Saponification, have you had it happen?

Post by Birrofilo »

I am very interested in this subject. I will be diluting my 95% ABV neutral soon into drinking strength.

My questions for those in the know:

a) Does saponification only happen in an alkaline environment, would a slight acidification of the liquor prevent the problem?
b) Is this a problem that only happens with wood-aged products, or is it possible to experience it also with aromatic neutrals, such as gin?
c) Does the problem occur only in presence of heat? (I don't think so);
d) Does the use of distilled water prevent the problem? (Maybe as it will be slightly acidic after exposure to ambient air for a while);
e) Is there a way to be sure to avoid the issue?

I am currently preparing my very first final product, a mistrà secco obtained by autodistillation, which means that I will "infuse" the alcohol while at maximum strength, and dilute it as the final step. Before dilution, the product is already "rich" in aromatic substances and essential oils, which I think should make me wary of saponification issues, even though I know essential oils are not "oils" strictly speaking.
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Re: Slow proofing and Saponification, have you had it happen?

Post by OtisT »

Sorry, I have not experienced that taste myself in my AGs so I have no answers, but I will add a question to the mix.

Some folks don’t like Cilantro because it tastes soapy to them. I have heard that only a small percentage of people experience this because they have some heightened sense of taste that others do not. Is the soapy taste in cilantro caused by the same molecule? If so, it stands to reason that in limited quantity, only folks with this super taster ability would notice such a taste in whiskey.

Cilantro = Coriander and I wonder now if any of these super tasters have an issue with Gin?

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Saltbush Bill
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Re: Slow proofing and Saponification, have you had it happen?

Post by Saltbush Bill »

OtisT wrote: Mon Jun 21, 2021 1:57 pm Cilantro = Coriander and I wonder now if any of these super tasters have an issue with Gin?
Reading I gave done suggests it is one reason that some people dont like gin.
The dislike of coriander is a genetic thing from memory.
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Re: Slow proofing and Saponification, have you had it happen?

Post by Hambone »

Wood ash can yield an alkaline (lye) tendency. This could cause saponification, as glycerine is the third most produced substance from yeast (after alcohol and CO2). Lye + glycerine = soap if I remember correctly…from Fight Club.

Overly charred oak? Not rinsing charred oak before adding to spirits?
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atarijedi
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Re: Slow proofing and Saponification, have you had it happen?

Post by atarijedi »

Hambone wrote: Mon Jun 21, 2021 2:14 pm Wood ash can yield an alkaline (lye) tendency. This could cause saponification, as glycerine is the third most produced substance from yeast (after alcohol and CO2). Lye + glycerine = soap if I remember correctly…from Fight Club.

Overly charred oak? Not rinsing charred oak before adding to spirits?
This is what I think it could be, you char the wood, you are potentially opening the wood to more easily extract potassium hydroxide, sometimes called potash. Which was traditionally used in making soaps from animal fats (the mono/di/triglycerides).

Which leads me to think that, if they didn't rinse the barrel properly, or in the case of hobbyists don't rinse their charred wood at all, it's entirely possible that a base hydrolysis reaction is happening between that now introduced KOH and the fatty acid esters that would already be present.

One of the problems as I see it though, in the rinsing, is that you are potentially losing water soluble flavour/odour compounds.
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Re: Slow proofing and Saponification, have you had it happen?

Post by Demy »

It has never happened to me but I always use the column for the final distillation (in various configurations) .. I specify this because in my opinion in pot-still mode some oils could pass in the distillate towards the end (tail) and this in combination with a ph in the "soap" range it could give rise to the phenomenon. It's just my guess.
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Re: Slow proofing and Saponification, have you had it happen?

Post by Birrofilo »

From this very interesting thread, I distilled this knowledge to "bring home":

"Saponification" is a non-issue unless charred wood is involved, or coriander.
In all other occasions, adding slowly water to distillate while mixing should work without problems.

Thinking better about it, I considered that:

a) most distillers dilute their product between distilling "runs". If after the first run one gets 60% ABV, normally one dilutes it to 40% or less before making the second distilling run. This is routinely done in the most cavalier way... nobody does it in many days or weeks!

b) Most grappa producers go very fast from pomace to shelf. Never heard about any precaution to avoid saponification in the Italian practice or tradition, either professional or moonshine, never heard about the issue at all. Most grappa is sold "white" but that which is "barricata", which is put into wood, is for what I know put in non-charred wood. Charring wood is a typical bourbon thing, I presume. And in fact, most of the scarce sources one finds on internet regarding the risk of saponification deal with bourbon.
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Re: Slow proofing and Saponification, have you had it happen?

Post by HDNB »

i got soapy once a few years back, but alas no notes. i think i may have tried raising the ph of some really oily low wines with baking soda but after 5 years, it's just a guess. never added baking soda again, never got soap again so maybe more than a coincidence.

i saw the word "esters" a few time up there^^^ im no chemist but i think it's alkaline+ fats that give soap.... long chain fatty acids + ethanol =esters.
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atarijedi
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Re: Slow proofing and Saponification, have you had it happen?

Post by atarijedi »

HDNB wrote: Wed Jun 23, 2021 3:57 pm i got soapy once a few years back, but alas no notes. i think i may have tried raising the ph of some really oily low wines with baking soda but after 5 years, it's just a guess. never added baking soda again, never got soap again so maybe more than a coincidence.

i saw the word "esters" a few time up there^^^ im no chemist but i think it's alkaline+ fats that give soap.... long chain fatty acids + ethanol =esters.
It is fats that give soap, after reacting with an alkaline base. Those fats are sometimes fatty acids, and sometimes fatty acid esters, they are called fatty acids because they are long carbon chain carboxylic acids (fat shaming), or the ester form because it's undergone acid hydrolysis to become an ester. Soaps are actually called fatty acid salts, fatty acid ester salts, or salt carboxylates, and have undergone base hydrolysis.

Lot's of times though, those fatty acids don't exist on their own since there are a bunch of alcohols present, as they may have reacted with an alcohol to create a fatty acid ester like linoleic acid + ethanol = ethyl linoleate. So that ethyl linoleate is a fatty acid ester.

So no, if you put it (acid or ester) into an environment where an alkaline base is present, like potassium hydroxide, that ethyl linoleate can be broken apart into ethanol and linoleic acid, and then the linoleic acid will react with that KOH to produce potassium linoleate, a fatty acid salt, sometimes called a soap because the reaction is called saponification or base hydrolysis, sometimes it's called a fatty acid ester salt because it used to be a fatty acid ester, and sometimes it's called a carboxylate salt because it's the salt conjugate base (potassium linoleate) of a carboxylic acid (linoleic acid).
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Re: Slow proofing and Saponification, have you had it happen?

Post by HDNB »

well that clears that up. :crazy:
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now i drink for evil.
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Re: Slow proofing and Saponification, have you had it happen?

Post by Harley »

A friend of mine made a batch of sugar vodka when he was starting off with the turbos and it came out really soapy.

We realised it was actually because he was experimenting with cheap unwashed fish tank carbon to filter his spirits. We figured that this dirty carbon was leeching salts and minerals into the alcohol that were reacting to cause the soapy flavour.

So based on the previous threads, perhaps spirits are at risk of saponification when there's any carbon filtration or aging of carbon barrels/staves? Although I think these can be mitigated
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Re: Slow proofing and Saponification, have you had it happen?

Post by Hogo »

Hi,
I have had this happen with a rum made from Jaggery Sugar. Although it didn't necessarily taste soapy.
I've tried multiple different things over many runs to try and fix it and the only way was to run the spirit run super super slow, (or chill filter).
A couple of points,
Diluting down slow or fast it always happened - Although I do dilute down slow for other reasons - diluting fast creates heat and this encourages vapour and aroma etc to evaporate. If you dilute quickly in a test tube you'll see bubbles forming from the chemical reaction (micro boiling?).

I would say that the oils are consistent throughout the whole run but the water/ethanol changes and as the run progresses the water content goes up to the point that the oils are not soluble (usually around 40%abv). You can check this by diluting the heads down to 40% as a a test...

I hope you managed to get tot the bottom of this topic!
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Re: Slow proofing and Saponification, have you had it happen?

Post by Avalir »

I haven't had this happen, but the fun word "saponification" got me reading. After dwelling on this a little while after reading through the thread. I found myself periodically having the same though pop up: saponifation sounds like sap. This got the gears turning and it finally clicked in a way. Sap! I then hit the research articles. The fatty acids that are likely responsible for for this have its highest concentration near the pith, followed by the sapwood, and the least in the heartwood. These fatty acids are also more common in soft woods than in hardwoods.
You have the type of wood question down, but I think you may be missing a couple follow up questions that many who have experienced the problem may not know the answer to.
You should likely also inquire about where in tree/trunk was the wood harvested from. And also, how was it cured/seasoned and for how long.
I think those may end up being key components in your investigation.

I apologize I couldn't give any first hand experience/knowledge. But I hope this at least gives you some food for thought.
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