Slow proofing and Saponification, have you had it happen?

Treatment and handling of your distillate.

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Slow proofing and Saponification, have you had it happen?

Post by atarijedi » Sat Mar 27, 2021 4:24 am

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.

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