Strong salty, baking-soda like flavor in Rum distilate

[Dman]

Hey Home distillers. Been ages since I’ve visited this forum. Good to be back.


I ran an experimental batch of high ester Rum, and this one resulted in a very odd, baking-soda like bite. Something similar only happened to me once before, and I found I was unable to distill this flavor out (going to try it on this batch as well). First thing I am concerned about is whether it's safe to drink.
The process was as following:

Fermentation:
20% dunder
All blackstrap for sugar, 1.098 S.G.
Nutrient was a mix of DAP and Valine + Leucine amino acids
1 multivitamin + 1 b complex (come to think of it, I think I might have done this last time I got this off flavor as well)
100g dead yeast
Pre-fermentation, added 10% of lactic bacteria, Panella fermentation.
Yeast was a Hernendal Kveik


Distillation:
Ran this through a double retort. First thumper was copper (primed with Rum tails), 2nd was stainless steel (primed with rum heads). I primed both of them with 1.5ml of sulfuric acid to promote cousins esterification.
What I didn’t realize is that stainless steel is corroded by sulfuric acid. The high wines in the steel thumper were cobalt blue. Though none of that color made it through to the distillate.
The copper thumper low wines were pretty deep yellow (which is also a first for me). Don't think it was due to puking as there was an union before the 1st thumper.

Any ideas of whatI might be tasting?

[MooseMan]

There's all sorts of things going on here that could have caused your issues, DAP, vitamin tabs, extra aminos, etc. but one thing jumps out a bit, and that's your mention of the acid affecting the thumpers.

By your explanation it's possible you managed to create a medium range sulfuric acid concentration, which is strangely worse than high or low, and removed the oxide layer on the stainless, creating god knows what metal salts, and probably alkenes from the acid/ethanol mix of high proof heads that would have reacted further.
And the same for the copper thumper, you probably made cupric salts. Not sure why yellow!
Not sure how much if any of this could come over in the distillate, but the alkenes would have I'm sure.

I would definitely not drink this!

[Dman]

Thanks MooseMan.

Down the drain it goes! You live, you learn.

During my last round I added the sulphuric to a pre mixed acid and alcohol blend. Mostly Butyric, acetic and propionic plus a mix of fusel alcohols and ethanol. All in a glass container. The results were great. I then tossed that into my primary retort. I guess most of the sulphuric might have reacted by then. Though the process felt a bit overly synthetic. Arroyo alluded to adding the sulphuric to the retort. So I thought I would give it a go and see what naturally occurring acids and alcohols react from my fermentation. So much for that.

The aminos were meant to promote specific metabolic pathways to create more banana-like esters.

I wish there was a good way to promote more esterification without a strong acid. The copper and heat in a high alcohol (low water) environment can only do so much. Maybe go for far smaller amounts of sulphuric?

Should I give adding the sulphuric only to the copper thumper another go, or am I playing with fire here? The sulphuric shouldnt react with the copper unless it’s pretty oxidized. I do give my copper equipment a citric acid wash before use.

Hope I didn’t mess up the dunder. It’s a 20+ generation.

[NZChris]

Did you check the pH, or just chuck a random amount of H2SO4 in it?

What is the pH of the distillate?

Try re-running it in a simple pot still to see if that cleans it up, or to learn if that flavor comes over early or late and can be cut?

[Dman]

Ended up dumping the lot. Nothing to test unfortunately (should have test ph). The alkaline compounds rang true. Definitely tasted that way. Didn't want to mess around with it.

The amount of sulphuric acid was a bit of an educated guess based on “Confidential instructions on making high ester Rum” scaled down to my fermentation size. It gave me a ballpark, though there was a bit of the “chuck an amount in” factor. Looking at my calculations I might have went 3 times the amount.

Cousins call for 2 pounds for 100 gallons high wines. Thats roughy 0.5gr (which is roughly 0.5ml) per half gallon. I put in 1.5ml.

[Yummyrum]

Assuming you only had 1litre in the thumper , if you added 1.5ml of concentrated H2SO4, it would have a molarity of around 0.027mols/L

That is a very very weak acid . I seriously doubt it could cause such corrosion to the keg .

[Dman]

The copper thumper had about 2L of primer. The smaller glass/steel thumper was likely closer to 500-750ml. though yeah. Still pretty weak.

I've attached an image of the thumper in action. You can see the cobalt blue color of the high wines. You can also see the chemical reaction on the stainless.

Interesting piece of information actually now that I come to think of it! The acid + heads was in the stainless thumper all night. It was only after I started running the still that it slowly started turning blue. Heat promoting a reaction maybe? Could something have been coming though the primary thumper?

[shadylane]

That's an undersized toy thumper, looks like it loaded up with copper sulfate.
But that's something usually caused by a pH above 7.
I'm fumbuzled about the blue but I'd not recommend the little thumper.

[Dman]

Haha. Yeah it is. The 1st thumper is 3.5 gallons (the thing in the top of the image is a vertical thumper). The kettle is only 10 gallons. So as a secondary the size fits well (and it indeed kept a good load for its size through the run). This was my first time tacking this one on to see what happens. Copper sulfate was my initial thought as well, though I’d expect it to be in the larger copper thumper if that was the case. And it’s also a very heavy compound, it would be odd for it to make it through to the secondary thumper.

The wash was just around 4.0 ph and the thumper loads were 4.8-5.0 + sulphuric. An alkaline reaction is possible though.

[shadylane]

This was my first time tacking this one on to see what happens.

There might be a clue right there.

[Dman]

Agreed, question is what’s the detail. I’m still hoping to run a double retort with this setup. I can’t see how size is a chemical influence.
Though the stainless steel can definitely be a factor. Though many folks run SS retorts. Trying to sort out what I miscalculated.

[shadylane]

Agreed, question is what’s the detail. I’m still hoping to run a double retort with this setup. I can’t see how size is a chemical influence.
Though the stainless steel can definitely be a factor. Though many folks run SS retorts. Trying to sort out what I miscalculated.

I'm thinking any problem isn't in the SS parts.

[Dman]

Agreed, question is what’s the detail. I’m still hoping to run a double retort with this setup. I can’t see how size is a chemical influence.
Though the stainless steel can definitely be a factor. Though many folks run SS retorts. Trying to sort out what I miscalculated.

I'm thinking any problem isn't in the SS parts.

Can you say more about the size issue? Would be curious to get your gut check.

[shadylane]

Can you say more about the size issue? Would be curious to get your gut check.

For Rum, thumpers need to be precharged and have head space left over to avoid overfilling before the run ends.
Just guestimation, I'd use thumpers at least 25% of the boiler size.

[NZChris]

You're not the first one to toss a product without allowing time for plenty of opinions and recommendations as to how to fix it to come in. I hope newbies reading this take note of that.

I've never had blue carry over into final distillate from low or high wines of any kind. I suspect that your blue was a non-volatile salt, but we will never have the opportunity to investigate it.

I've been using H2SO4 for rum for over thirty years in a copper & SS still and never had a problem, so I wouldn't blame it without knowing the pH in the retorts, wash, distillates, dunder, stillage, etc..

Cousins uses lime salts. You mention Cousins, so were you using lime salts and how did you make/obtain them?

[Dman]

You live you learn…

I’m very happy not to blame the H2SO4 as I plan to use to again.

This is only my 2nd time using sulphuric, so I’m still learning the ropes. My general understanding of the cousins process (and correct me if I’m wrong) was to use lime salts to in order to reuse the acids in solution by crystalizing them. I have not tried that. The only thing I am currently using from that document is trying to push esterification by using a strong acid as a catalyst. Once I get that process stable, I’ll start looking into recycling.

I’ll repeat this experiment and take better measurements. I’ve been making Rum for a few years now, this is the first time things went so far sideways.

Though it’s also the first time I’ve tried amino acids as a nutrient source. The chemistry made sense, but who knows what kind of reaction I didn’t account for with all the compounds in the molasses, or dunder.

[MooseMan]

It may well have been nothing to do with the Sulphuric, it just stood out to me in your initial post and there are several things that could have happened as reactions.

Speaking of reactions, you have mentioned trying to push esterification by using the strong acid as a catalyst. Are you adding live dunder/muck to the mix? What is it you are trying to esterify?

The issues you had could just as much come from the vit tabs, or the extra nitrogen you added, playing with the DAP.

Maybe strip it all back and start again from the beginning with the next rum, and only change one thing at a time.

[Dman]

As for muck, I used a controlled bacterial fermentation I was running on the side as my acid source ( 3.4 ph). About 10% overall volume.

That’s indeed what I’m going to try. Cut the tablets and aminos and try it fresh. The question is, do I dump the dunder as it likely still has traces of those compounds.

[NZChris]

I thought muck pH was supposed be around 5 to encourage bacterial growth and the formation of carboxylic acids?

[Dman]

I might have been too vague in the above comment. I am not using actual Muck. Instead, my source of acids is an un-ph-buffered, controlled bacterial fermentation. Using a combination of a few different strains of Lactobacillus and Closridium butyricum. What I end with is a bucket full of puky funk at a ph of 3.4. Something like a combination of Kvass malt beer and parmesan cheese.

I am actually just now starting my first earnest attempt at a muck bucket. As I mentioned a few posts back. My current methods are getting too “synthetic” for my liking. I’d like to see what some wild factor gets me.

[Yummyrum]

I have to say I’m surprised your dunder is 3.5

I’ve been making all mollases rum for over 10 years and every single time , the Dunder is pH 5.0 +|- 0.1.

To pH adjust all Molasses Dunder from 5.0 to 3.5 takes a lot of very strong acid .Those cultures must be amazing if they can sour it that much .