Inoculating dunder with lambic strains

[MtRainier]

I’m starting up a dunder pit and purchased some lambic, sour beer, strains to start it off.

Going to do the wild yeast brettanomyces blend of WLP648 as well as WLP661 which is pediococcus damnosus and let them battle it out. White labs says that the 661 is a high diacetyl producer which sounds good to me. I may try other sour strains from time to time as I add and remove dunder for the batches to see how it all evolves.

I’ll report back if anything good or bad happens. I’m a lambic fan and rum dunder seems up that alley.

[Beerswimmer]

Sounds good. Are you going to have any sugars in it?

[MtRainier]

Probably almost no sugar left, just what would be left after fermenting the molasses and doing the stripping run.

I can always put some fresh molasses in there intentionally with the cooled dunder after removing for the next batch if it seems to be doing nothing. I figured the lambic bacteria strains could use some of the non-fermentable components in the dunder.

[MtRainier]

I did put a bit of unfermented blackstrap molasses in it two weeks ago. Not a lot. Maybe a half cup.

It's growing a light tan pellicle which is a bit powdery but sticks to the plastic thief when I pull a sample out. The pH is sitting at 4.34, which seems ok. I've put three generations of backset in it by removing 1.5g to add to the boiler charge and adding back 1.5g after running and cooling.

It smells like funky butterscotch bananas.

[Beerswimmer]

Nice!! I have a bunch of brett and LAB's, I might pitch some and see what happens.

[MtRainier]

I have 12 gallons of Bucaneer Bob's Rum that got the sugar addition about 10 days ago but is slow finishing out all of that sugar using FermPro 921 yeast, it seems.

I'm tempted to add a small amount of this lambic dunder to the fermenters to see if it will get more interesting and a bit dryer with the Brett strains added.

[Oldvine Zin]

I'm all for funk in my dunder pit but I have to say after years of wine making i've become very brett sensitive for me brett has no place in any wine or spirit or any other place that crucial decisions need to be made

just my opinion
OVV

[pope]

Was there any evolution in the use of your dunder pit, MtRainier? I'm thinking of culturing some of my own White Labs bacterias in a dunder pit.

[MtRainier]

It has a ton of "rotten banana with butter" smell in it and is very sour if I boil up a bit and taste it. I can't say that it does much for my rum. The pellicle kind of settled down and went away. I suspect there just isn't much in there to ferment. I'd like to put some more bacteria in there to handle stuff that isn't sugar. I can't say it is continuing to change, but it's possible something is happening in there. I'm not doing anything special to it except for looking at the air lock every couple of months to see if it needs more water.

I added fresh backset a few months ago when I did my last rum ferment after taking out 2 gallons and boiling it up with yeast (for nutrient and to sanitize it) and to dissolve the molasses. I do 100% blackstrap molasses for fermentables, so there should be some good stuff left in it that the yeast doesn't get in my 5 days of ferment.

[Single Malt Yinzer]

For me seasoned dunder is about bacteria, pH, nutrients and wild yeast. If you want to pitch a commercial yeast just pitch it in the wash before you add the seasoned dunder. After a run there won't be much sugar left for any yeast to grow. If you toss in a commercial yeast it will either die or not grow much. If you add the dunder it's not going to have as much of that yeast as you would in a standard packet. It will be a small amount of yeast amongst the rest of the microbial material.

If you're using seasoned dunder at the start of the fermentation you'll be losing alcohol yield to things that are not yeast. Pitch the yeast you want the flavor of then wait a day or two and add the seasoned dunder.

[MtRainier]

SMY, I wouldn't use dunder to contribute microbes for fermentation. I think that's what you're talking about here, and it's a cool idea, but not one that I've tried. I use it for flavor enhancement, trying to get some of that funk into the vapor during distillation.

I don't know the right spot in the rum run for doing that. I'm experimenting with it. The last batch I sterilized it by boiling it and then added it at the beginning of the ferment to lower pH instead of citric acid. I've also done a batch where I added it to the boil right before the stripping run. I'm considering doing one where I add dunder to the low wines to get that funk into the output of the spirit run.

[Single Malt Yinzer]

There's no laws when using dunder. For what you're trying to do it's working so keep at it. Boiling will kill pretty much everything but spores can survive. I wouldn't consider it huge thing as they won't have much time to grow. For greatest effect I would put it in at the start of the ferment so the yeast can have access to the fatty acids to make esters.

[pope]

SMY - so in a typical rum batch if I have 12-gal and I pitch my commercial starter, I come back to check on it around 10-12 hours to buffer if needed, would that be when you'd add some of the cultured dunder? How much would you suggest adding at a starting point?

I'm interested in adding the flavor potential of a dunder pit to the wash at whatever becomes the optimal point pre-stripping, since my next step would be to crash pH with sulfuric and use a dephlegmator to drive esterification to maximize flavor potential of the dunder contribution. But I've never had a dunder pit so it's all pretty theoretical at this point.

Side note, I'm very glad I found this thread!

[Single Malt Yinzer]

So everyone realizes that you can do what you want - just think about what you're trying to accomplish with your methods.

The way I do it is that I let the commercial yeast eat up most of the sugar, 2-4 days. Then I add a small amount of seasoned dunder - say 1 cup to a 5 gallon wash. It doesn't take much. Bacteria will use some fermentable sugar so I try to limit it to smaller loses. They can also ferment more complex sugars that yeast cannot so they are happy with leftovers. Give that a week or two. Even though there is little or no yeast activity the bacteria is still going. After I pitch the seasoned dunder I prefer to go to a closed fermenter so that acetic acid bacteria doesn't use up the alcohol either. I usually use carboys so open I leave the top covered with a paper towel but otherwise open to the world, closed I just put an stopper & airlock in.

If you're using fresh dunder or doing what Mt Rainer is doing it's going to be different.

[pope]

Totally, that's the beauty of it! There are so many ways to achieve better/more interesting spirit, but it's still nice to be learning from others' mistakes and successes where possible.

I would guess I'd start with a small pitch of one 'vial' of a white labs culture into a small 2-ish gallon bucket of backset/dunder. Maybe strip it a few gravity points early to leave a little more sugar in the first batch of backset. Would adding fresh molasses/sugar help get it started? This is sounding like molasses kombucha... anyway. Then cycle it with every stripping run, dumping half or maybe 1/4 (less the 1-cup-per-5-gal innoculation) and replenishing after said batch is finished.

A few questions - as the bacteria continue breaking down sugars, do you see gravity continue to drop after primary fermentation is complete? Do you have target pH and temp parameters that are different from your primary fermentation parameters? I aim to stay above 4.0 and use lallemand rm/danstil 493 (same thing), so I stay in the 81-86F range. Should be 86-95 but I need to change my gear to get higher. Though I aim to stay above 4, if by 1.000 I'm drifting into the 3.7-3.9 range it seems to still finish out fine.

[Single Malt Yinzer]

Would adding fresh molasses/sugar help get it started?

Yes. Some in the rum world to feed dunder pits fruits and other sugar/flavorings. It's important so that it doesn't mold over.

do you see gravity continue to drop after primary fermentation is complete?

Yes. It can go below 1 due to the presence of alcohol.

Do you have target pH parameters

No - I just keep it above 4.

Do you have target temp parameters

Yes - I start at a set point (normal 76-80) and after the heat of the primary ferment I turn the heat up a degree every day or so until it's mid-high 80s.

[pope]

Thanks for all the help!

I've been getting anywhere from .999 with cane down to .991 with agave, interested to see if I can go lower with bacteria on the tail end. Dunder pits used to sound very mystic/mythical but they're now starting to sound more like a sourdough/kombucha/kefir culture. Just a pot full of healthy microbes to bring flavor to our world.

Will a dunder pit come back to life after days/weeks/months of neglect or is it a daily maintenance ordeal?

[Single Malt Yinzer]

they're now starting to sound more like a sourdough/kombucha/kefir culture. Just a pot full of healthy microbes to bring flavor to our world.

That is really what it is. Nothing magical about it.

Will a dunder pit come back to life after days/weeks/months of neglect or is it a daily maintenance ordeal?

I tend to dump mine after a while and start over again. Can you bring it back? Probably but I haven't tried.

[SaltyStaves]

Will a dunder pit come back to life after days/weeks/months of neglect or is it a daily maintenance ordeal?

If nature is left to take its course, the bacteria can turn a pit to water, ammonia and carbolic acid. Acidifying the pit will make it dormant and lock in the precious acids. To restart it, a strong base like slaked lime can be used.

My pit has been left for months with a pH around 4. It is pointless to try and culture bacteria in an outdoor pit during cool weather. I'm waiting for the hot weather so I can restart it again. If you have an indoor pit and temperature control, then you could skip the whole dormant/active cycle.

[pope]

As a hobby I'll probably just start it indoors with an innoculant (looking at White Labs 655 which is "A unique blend of Brettanomyces and Saccharomyces yeasts as well as bacterial strains Lactobacillus and Pediococcus"). I'll keep it hot (mid 80's F) and > 4 pH and feed it a little with fresh backset and molasses with every distillation while I try some different tweaks to test batches and then toss it. I'm sure I'd keep it going if I went pro.

Salty it restarts after you crash it's pH? I guess that's from bacterial spores? So interesting.

[SaltyStaves]

Salty it restarts after you crash it's pH? I guess that's from bacterial spores? So interesting.

Crash? I think you mean raise. Crashing is when I leave the pit dormant (acidic) over the winter.

I think you are only concentrating on aerobic infections that only favour a very acidic environment. My pit is also used for anaerobic bacterial development too (summer). I'm not only giving my bacteria lots of sugar and oxygen and a highly acidic environment to play in, I'm giving them dead yeast, waxes, fruit peels and vegetative material and a slightly acidic environment (pH 5.5-6.5). It depends on what I'm developing and I don't try and do it all at once.

The point is, acids and bases are used as levers to stop/start the pit.

[pope]

I meant you can revive it (by raising pH) after you've already crashed/lowered it. Without thinking it through my gut feeling was that you'd kill microbes with an acidic crash but it makes sense that nature would find a way to survive adverse conditions. Other than a light perusing of other posts I really settled on this one to start my dunder pit journey so I'll have to pull up other posts and give them a thorough read-through.

[SaltyStaves]

You will need new bacterial colonies. Acidifying the dunder will stop them eating and kill them. The important thing is to lock down the carboxylic acids that they have created at the time they were active. This is especially important if you aren't ready to use the dunder. Acidifying it, allows you to draw it at a later stage, safe in the knowledge that they aren't going to continue feeding until they've run out of food and then start eating each other.

But that is only important if you have a discontinuous cycle (like with a seasonal pit).

[pope]

Gotcha. So you're using it for the acids themselves, not as a culture to inoculate a freshly yeasted rum ferment. What acid do you use to acidify?

[SaltyStaves]

Gotcha. So you're using it for the acids themselves, not as a culture to inoculate a freshly yeasted rum ferment. What acid do you use to acidify?

Infecting rum washes tends to be unpredictable and non-repeatable. I've tried it a few times with more failures than successes. I stick to adding the infected dunder to finished wash or low wines. Its more volume to strip, but it can be trialed first before committing.

Banana/Cane vinegar, previously infected dunder and Lees are what I predominantly use to acidify the pit.

[pope]

Never heard of banana vinegar but that sounds like the perfect kind of acids to be adding to a rum ingredient. Makes sense it's more consistent, how much volume from the pit does it take per volume of wash to get the kinds of flavors you're after?

[SaltyStaves]

Never heard of banana vinegar but that sounds like the perfect kind of acids to be adding to a rum ingredient. Makes sense it's more consistent, how much volume from the pit does it take per volume of wash to get the kinds of flavors you're after?

I have greater access to bananas than sugar cane, so I have more of it than cane vinegar.

I have been following something similar to Hampden Estate's process with 36% dunder/muck with as much sour cane skimmings as I can get, combined with 64% freshly fermented rum and force aerated before distilling.

[pope]

Wow! Way more than I expected, glad I asked.

[Corsaire]

Cane vinegar, especially infected cane vinegar is what they use at worthy park I'm told. They don't do muck pits but do have a funky jamaican rum.