Kettle Soured Rum

[Donny3000]

Hello all,

I was unable to find much on kettle souring of any kind of wash or mash specifically to be distilled, so I thought the best way to find an answer would be to test it. So heres my plan.

Follow Buccaneer Bob's steps for making the wash, but instead of adding yeast, I will lower the ph to about 4.5 and add l. planatarum (from a Mango Goodbelly drink) and keep it warm for about 24 hours. This should bring the ph down to about 3.4. At that point, I will bring the wash to a brief boil to kill off the lacto, cool it down, then pitch my yeast.

Im hoping this will produce some funky esters and replace the need for a dunder pit. If anyone has any suggestions on how I should alter my plan or has any input please shoot it my way. Will post updates for this project.

[Dr Griz]

I'd love to hear how it turns out, but I gotta tell ya, I'd be a bit worried about running the starting pH down too low on a rum wash -- I gather that, unlike an AG mash, molasses or brown sugar don't have much in the way of buffering capacity, and the yeast tends to run the pH down as it is. Of course, it depends a lot on your yeast, but I've had rum washes stall out where you're planning to start.

But I'm keen to hear what more experienced hands have to contribute!

[Donny3000]

That's something I'm definitely going to keep in mind. I have some EC-1118 on hand which should help if it stalls, but if that doesn't do the trick I might add some yeast nutrient or calcium carbonate to bring the pH back to a level where the yeast are happy.

[NZChris]

The ester precursors in a dunder pit are created by bacteria thriving in a comfortable pH for them. Bacteria don't do well in a low pH environment, so if you start a rum ferment with a low pH and no dunder, where will your carboxylic acids come from?

[Saltbush Bill]

If your trying to get flavour in Rum Id suggest you use a yeast other than 1118

[Yummyrum]

Sounds all wrong to me .
Yeast don’t like pH that low ( 3.5pH) and if you intend to add calcium carbonate to raise pH , what was the reason for lowering it in the first place

[Donny3000]

I'm going with the classic bakers yeast, the EC 1118 is only for if it stalls. The calcium carbonate is also just in case it stalls, I'm hoping i wont need to add any.

As for the low pH, lactobacillus planatarum benefit from a lower pH, and at the end of the souring they should in theory have produced plenty of lactic acid and some interesting flavor.

I'm aware this project will probably not turn out well, but I hadn't seen any discussion about distilling kettle soured mash or wash, so I thought I might as well try it and see what happens.

[Dr Griz]

I reckon that if your only goal is to bring down the pH, you may be barking up the wrong still column -- the pH might be a bit too low, and besides, if that's what you want, it's easier to just dump some lactic or citric acid in at the beginning.

But it sounds like your goal is also to bring in the kinds of funky esters that a good sour beer has. So even if you end up having to bump up the pH later, you might still get something interesting. I guess the real question is what kinds of flavors this particular culture you're using will produce.

I guess the only way to know is to experiment! I sure hope you'll keep us posted!

[Donny3000]

Update: Wash finished fermenting and is undergoing a stripping run. I let the wash sour for about 24 hours with a mango Goodbelly drink which brought pH to 3.5. This was brought to a brief boil (like 5 min and covered) to kill the lactobacillus and cooled before about ~30g bakers yeast was added. Starting gravity was 1.085 with pH of 3.4.

This fermented for a few days with a heating pad keeping it at 83*F, then I added 4lbs of morena sugar and let it ferment out. FG was 1.009.

Still got a ways to go on this project, but the smell of the wash as it was going into the boiler was fantastic so i'm optimistic about how this will turn out. Will post updates when I've done a spirit run and let it sit on oak for a few weeks.

[Dr Griz]

I don’t wanna sound all pretentious, but I’m really hoping you could elaborate on the fantastic smell. What kind of notes were you picking up?

[Donny3000]

Working from memory here, but it smelled pretty fruity, a little sour, a little funky, overall tropical. Its been a bit since my last batch of rum and I didn't pay super close attention to the smell of the wash (3rd gen bucc bobs rum) but from what I do remember this one smells similar but more fragrant and a bit fruitier. The mango comes across a little, but the smell is almost closer to like papaya or a faint guava.

[Dr Griz]

Groovy! I hope a lot of it comes through in your final product -- I reckon the more esters, the more transesterification!

[Donny3000]

Update:
It's been on a mix of 2nd and 3rd use oak for 18 days now, and the tropical flavors have mostly disappeared. I compared this batch to a 4th generation rum I made recently (aged 22 days with 2nd use oak) and the flavors are almost the same, although I hesitate to attribute the flavor to the kettle souring as most of the new flavors I got from it as white rum have since disappeared.

Altogether I don't think it's really worth it to kettle sour the rum given the extra work it took for how little the flavor has changed.

I'm gonna let it keep aging and then give it a couple weeks once I proof it down to bottling strength, and will post another update if it's improved in flavor or if some of the early flavors come back. Worthwhile experiment even though it didn't turn out any better than a normal batch.

[NZChris]

18 days???

A couple of days ago I noticed that I hadn't tasted my latest batch of rum for 17 months. I'll try to remember to have a look for it tomorrow, but I expect it will be a bit young yet.

[Saltbush Bill]

It's been on a mix of 2nd and 3rd use oak for 18 days now,

Agree with Chris , 18 days wont even give you a hint of what it might be like in 12 or 18 months time.

[Donny3000]

I only run an 8 gallon boiler, and this was a single batch, which yielded a bit over a half gallon of good hearts at 65%. Like I said I'm gonna let it keep going for a while, I just wanted to give it a comparison when it was close in age to the last batch I did, which turned out phenomenal (at least for my personal tastes). For what its worth I also thermocycle the jugs I age spirits in with a heating pad to be 24 hours on and 24 hours off to coax the spirits in and out of the oak to make it closer to what a barrel in a rickhouse would achieve. It's not a replacement for time but it definitely makes the spirits taste better when aging short periods.

I've only been running liquor for about 5 months now so I'm still just trying out a bunch of recipes in single batches to see what I like before I do larger batches where aging for a year+ would make sense. I do appreciate getting the feedback from you longtime pros though, and will make a note to start some projects to be aged in years rather than days.

[Donny3000]

Final Update:

I used too much oak, and had to pull it off the oak after 33 days to avoid it getting too oaky (at least for my own taste). After proofing down to 45% and letting it sit for about a week, here's my final conclusions. The rum starts with a bit of a guava/juicy tropical flavor, and fades into a bit of a muted earthy/mossy flavor on the backend. As a whole its pretty good, but for my own taste I would not consider it superior to my usual rum. I tried to keep as many variables between this rum and usual recipe constant save for the kettle souring, but shit happens so it wasn't a perfect experiment. I'm hesitant to attribute the early tropical flavors to the kettle souring process but I suspect it's what caused it.

Overall I would say it was worthwhile to at least test, even though it did not yield a fantastic result. If I were to replicate this (and eventually I probably will) I would use like 1/3rd the amount of oak cubes and let it age for 3-6 months. I'm still a noob at this so theres probably a lot more that I missed here but I tried, and I'll try again when I've got more experience under my belt. Thanks for following this thread and giving me input!

[Hogo]

Hi,
I have a similar method but pH was 5-5.5 on pitching yeast, then left for a few hours before pitching L.Plantarum... this ferment was left for 14 days. Towards the end a slight Lacto layer was forming on top of the ferment. the yeast had no problem finishing off fermenting.
Double pot stilled this. Definitely gave more complexity to the rum and a slight more funkiness. Currently sitting in a barrel and will try after two years (or maybe sneak a sample every 6 mths for quality assurance purposes only...).
Cheers

[Hogo]

Hi,
I have a similar method but pH was 5-5.5 on pitching yeast, then left for a few hours before pitching L.Plantarum... this ferment was left for 14 days. Towards the end a slight Lacto layer was forming on top of the ferment. the yeast had no problem finishing off fermenting.
Double pot stilled this. Definitely gave more complexity to the rum and a slight more funkiness. Currently sitting in a barrel and will try after two years (or maybe sneak a sample every 6 mths for quality assurance purposes only...).
Cheers