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Now normaly folks I dont bother. So far I have only done double fermentations, using dunder from the first strip run to start the second wash.

I am considering setting up a "Dunder Pit" not quite in the traditional sense. I am thinking say a 30 to 50 gallon HDPE open top drum. Now I know the top layer gets mouldy and you use the middle layers, but are there any problems I need to be aware of. Does it work in our cooler climate - this is not the Caribean after all.

The principle seems to be bacterial growth/fermentation of the residual unfermented sugar to cause esterification and an increase in the concentration of rum oils and other congeners. On a small scale is there a significant improvement in flavour? Is there any risk of growing nasties? A dose of food poisoning is not my idea of a good night.

Are any of you actually doing it?

Dumb question maybe but wouldn't the continuous use of dunder batch to batch be essentially the same thing? Wouldn't the bacterial growth and fermentation of the unfermented sugars happen in the new wash anyways if you keep reusing the dunder batch to batch. Kinda like what happens with backset with grain based ferments. bd.

I haven't used this as a continuous process a la 'dunder pit', but I have racked off rum dunder from under mould before. it worked fine, and no one got food poisoning I didn't notice differences in taste. Hope that helps to alleviate some fears? sorry I can't shed light on the continuous thing. Oh, I should add, my dunder went mouldy in an open top container in a shed at about 5*C, so I don't think it will make too much difference not being in the tropics you could try leaving it in the sun if you wanted bacteria that like high temps. wrap in black polyethylene?

I've asked myself the same question many times Myles, but like you I was also concerned. I've done multiple runs using dunder from the previous batch for up to five or six times, but it's always been fresh. Whenever I keep it for a month or so the mould scares me enough to not use it. I'll be watching this interesting thread. Thanks for raising it.

blanik

Yes blanik you have the point. There is a difference between using dunder from run to run, which has basically been sterilised and then stored for a short time. As opposed to growing a long term bacterial fermentation in a dunder pit.

Know I know it is how they do it old style, but I got a bit nervous the first time I tried, about the mould that grows on the surface. Even if there were some nasties in there I doubt anything toxic would get through the still

There is a difference between using dunder from run to run, which has basically been sterilised and then stored for a short time. As opposed to growing a long term bacterial fermentation in a dunder pit.

OK Myles, I get it now. It sounds like a really interesting idea. bd.

I have been re-reading the articles and the 1945 Arroyo patent, and they all state simmilar things. Various bacterial contaminants that occur naturally in the soil and sugar cane are responsible for the bacterial fermentation in the dunder that causes production of the esters that dominate the tails and improve the flavour.

However they also say that these can cause problems. Now I dont have access to cultures of the specified Clostridium bacteria, but I know that it will get contaminated spontaneously if left open to atmosphere.

Has anyone had any success with wild bacterial fermentations of dunder? Or are there any horror stories of how it has gone wrong?

I have been re-reading the articles and the 1945 Arroyo patent, and they all state simmilar things.

Where is this literature Myles? Do you mind sharing? Thanks, bd.

No problem at all. Found some good stuff here in the library:

http://distillers.tastylime.net/library ... /index.htm

http://distillers.tastylime.net/library ... /index.htm

Also came across this

http://etd.lsu.edu/docs/available/etd-1 ... thesis.pdf

And these:

http://homedistiller.org/forum/viewtopi ... =11&t=6871

http://homedistiller.org/detail/362ChapterThree-c.htm

http://www.1911encyclopedia.org/Spirits

Lastly this is a LONG LONG read be warned

http://books.google.co.uk/books?id=13Ey ... er&f=false

Am sure there are lots more articles out there waiting to be found again.

Thanks for those links Myles. Cheers, bd.

Has anyone outside the caribean any experience of trying this? I just ordered two 220 litre screw top plastic barrels. They used to have olive oil in them but they should clean up ok. The big screw top will let me skim off the ineviteable mould, and a tap further downshould be fine for taking off the dunder. Just don't want to poison anyone. Xpecially me!!!

It should get pretty acidic, so I don't expect anything really nasty to grow. Anyone have any comments / advice? Is it worth the effort over the normal practice of storing dunder just from 1 run to the next?

Thanks myles, great links, Im just not sure anymore whether I want to make rum or move to the Caribbean..

Cheers

I live in the tropics and have been using dunder that's now several months old months old with lots of mold, bacteria and god knows what else growing on it. For may last wash, I heated it up to boiling before mixing it with the molasses and water. I figured it would be better to kill off any potential nasties before throwing the yeast.

guillermo wrote:I live in the tropics and have been using dunder that's now several months old months old with lots of mold, bacteria and god knows what else growing on it. For may last wash, I heated it up to boiling before mixing it with the molasses and water. I figured it would be better to kill off any potential nasties before throwing the yeast.

Nice one guillermo Have you noticed a significant difference between the rum made with the aged dunder and what you started out with at the begining?

As you are still doing it - it sugests it is worth while. Or are you still evaluating the process??

Hi Guillermo - just a couple questions from the uninitiated.

For may last wash, I heated it up to boiling before mixing it with the molasses and water. I figured it would be better to kill off any potential nasties before throwing the yeast.

Do you hold back some of the "living" dunder?
Also, how long before the dunder gets infected? I ready to strip my first molasses wash and was wondering that. Thanks, bd.

I am fermenting now in 150 litre drums. I am thinking for the rum that I will do 100 litres at a time as this should strip down just about right for my still. I may use one of the 150 litre drums as a low wines store. For my dunder store I have ordered a 220 litre screw top drum. Now for 100 litres I will only use 20 to 30 litres of dunder so I should be able to get quite a colony growing in the store. Well that is the plan.

I see. Are you going to add some dunder to your spirit run like one of the articles mentions? I think that's what I read Cheers, bd.

Miles wrote:

Have you noticed a significant difference between the rum made with the aged dunder and what you started out with at the begining?
As you are still doing it - it sugests it is worth while. Or are you still evaluating the process??

I'm still evaluating. I started making rum a year ago and so far have a couple of 5 gal.wooden barrels aging and am working on a third. I changed my approach after I visited a rum factory. They let me taste their fresh distillate that was 70 ABV and it had more flavor than the stuff I was making (it still didn't taste like anything you'd want to drink because it hadn't been in the barrel). Now I'm using more blackstrap and the moldy dunder in hopes of getting more rum oils and thus flavor. I'm also using a bigger fermenter so I can do 100+ liters at a time. I like your your idea of using a large container for the dunder. I've been using 5 gal pails with lids I don't seal completely.

blind drunk wrote:

Do you hold back some of the "living" dunder?
Also, how long before the dunder gets infected? I ready to strip my first molasses wash and was wondering that.

My dunder starts growing mold after a week or two. I'm in the tropics and store it at room temperature. I use the fresh dunder if I don't have the old moldy stuff.

I recon if I can build up to having 200 litres of dunder in storeage, and I am only using 20 to 30 litres at a time, then I should get a fairly consistent flavour contribution form the dunder store. It should also even out the acidity at a stable level I hope. Part of it is about flavour, part acidity and part yeast nutrient. Will have to see how it works out.

I have a gallon of dunder that I saved - in an airtight container - from when I first read this thread and I just went and had a look at it. It has a few 'flakes' of mould floating, and I mean a few, and it looks clean and smells delightful.

I reckon it's time I made some rum and tried this.

blanik

I'm sceared.
Might need to wait for one of you fine gents to offer up a tutorial when you get the questions and such ironed out.
I with you in spirit though.

mmm 200l foodgrade barrels are cheaper than the brewshops are selling their 25l fermenters... I see a dunder pit in my near future (and probably a fermenter upgrade!)

Old thread but just started a dunder pit after my first rum run couple weeks ago. Not big on rum myself but now I know why. Local commercial stuff is crap. Did hookrum and fantastic. So I used a spare 5 gallon fermentation pail (enough laying around now that I upgraded in size). I put two layers of cheese cloth over then the lid. I put a wad of cheese cloth in the airlock hole to keep bugs out. Checked it yesterday, has a layer of scum and some mold starting nicely. Smells very pleasant surprisingly! Fruit flies trying to get in bit the cheese cloth has foiled them! Can't wait to try this method now!


*edit* stupid phone split my post somehow

So now my dunder has a nice thin layer of white on the surface. It still smells very sweet and pleasant. Everything seem ok? Posting pic of my "rot pot" aka dunder pit.

moosemilk wrote:Old thread but just started a dunder pit after my first rum run couple weeks ago. Not big on rum myself but now I know why. Local commercial stuff is crap. Did hookrum and fantastic. So I used a spare 5 gallon fermentation pail (enough laying around now that I upgraded in size). I put two layers of cheese cloth over then the lid. I put a wad of cheese cloth in the airlock hole to keep bugs out. Checked it yesterday, has a layer of scum and some mold starting nicely. Smells very pleasant surprisingly! Fruit flies trying to get in bit the cheese cloth has foiled them! Can't wait to try this method now!


*edit* stupid phone split my post somehow

I just started hook rum a couple days ago. I am thinking along the same lines you are: ill add my dunder(backset) to an empty carboy. I was thinking of using a nonscented babywipe to cover the top and use an elastic to keep it on. Whether it gets cruddy or moldy- as long as its brought to a good boil, then through a still (potentially 2x) - i cant see any sort of pathogen making it through...im not a dr, but well educated in laboratory science. If im wrong please school me

I could be wrong, but from everything I have read here and elsewhere, what I got is that there is no known pathogen that could survive in the vapor path. Besides, most Caribbean rums use dunder pits,and I have never heard of anybody Contracting ebola or the likes from drinking rum. And you are not trying to get the mold, you want to rack from the middle between the top layer of mold and all and the bottom sediment layer. I may get corrected, but this is what all my reading has lead to

Spores and prions can infact survive the temps of stilling. Some are pathogens . I should retract my last thread. I cant find any literature on the topic of pathogens and distilling. Most "bugs" that cause sickness WILL be killed.

freshwaterjellyfish wrote:Spores and prions can infact survive the temps of stilling. Some are pathogens . I should retract my last thread. I cant find any literature on the topic of pathogens and distilling. Most "bugs" that cause sickness WILL be killed.

Good to know, I'm still doing reading on the whole thing. Have you come across anything about them surviving in an alcoholic vapor path though? That seems to be what most of the references are too. May be able to survive temps, but what about the alcohol at those temps also? And with a dunder pit, you wouldn't be going after the top crust where the spores would tend to be, so maybe that's key as well

Spores tend to float. Using below the surface of a dunderpit would cut the number tremendously, (thats my plan). Many cleaners we use are disinfectants; they kill/hinder bacteria, but not always their spores. Sterilization is what kills the spores. In lab we use autoclaves to sterilize equipment. This uses moist heat and alot of pressure (much more psi than a still)alcohol (used at 70%) will denature proteins.

I try makeing rum from birdwatcher's wash and give molasses* only to the low wines for flavour (as molasses are not easy to aquire here) before distillation, I wondered is the spent wash (sugar+tomato+citric acid+yeast) should work as a dunder too? Also, should one also pour the dead yeast cells that thickened in the fermenter's bottom into the dunder pit?

*Lyle's black treacle, it says it is sulphured, will three heaped tablespoon (<200g) added to the low wines give a recognizable sulphuric smell or taste? Never done it before, so I thought those who play with dunder-pits here are the pro's in rum making, this is why I dare to ask here.
Thank you.