Long-term wild yeast incolulation of open-air dunder

[RumFiend]

I'd recently left two separate fermenters each with 4L of undiluted stockfeed molasses in my shed with no lid on it only to find that about a week later one of them had started fermenting from whatever the hell was in the air during that time. I could hear fizzing and see some bubbles evolve through the thick mess, and there were the slightest traces of something very faint white-green 'mould' growing on the surface. On later visits the whole surface had become overrun by the mystery 'mould' and only after shaking the fermenter to redissolve the mould could anymore fizzing be heard (this could just be trapped gas being released and not the mould continuing fermentation).

Then I decided to explore this Clostridium bactyricum bacteria in more depth and to cut a long story short and avoid the summarising of about 6 hrs straight meta-research of this crafty little critter til 6/7 in the morning, I found a paper which explored the inoculation times of C. bactyricum using batch and fed-batch methods, i.e. having all the glucose available at once, and having the glucose slowing introduced over time, respectively. And in that paper they found that the ideal pH for quickest growth was 6.5.

Well..

All this has inspired me to conduct a experiment to explore the variations in yeast and bacteria - "wild yeast" - populations in dunder and their associated flavour effects, across a strata of pH levels starting from 4.5 and incrementing by a pH of 0.5 up to 7.5. It's hoped that there will be observed a variation in the spectrum of species that dominate each mini dunder pit and this will express itself with a unique set of congeners.

Eight 700mL glass bottles containing 500mL of dunder will be placed in my backyard and observed over a period of time to see what kind of effect pH has on being selective for and against "wild yeast" strains.

So here's my method so far:

4L of 3rd generation pugirum dunder was brought to a rolling boil and left for 25 minutes to kill off any existing yeast and most bacteria present, and evaporated any trace alcohol that may have fermented out from leftover yeast*. This provides a stable starter medium for wild yeast and bacteria that waft in over my backyard to inhabit.

After 25 minutes of rolling boil the first 500mL aliquot was taken from the pot by way of alcohol-sterilised pipette into an alcohol-sterilised glass jug. The pH was tested, and the temperature adjusted for 75C, and found to be 4.08, a little too high for the first sample. Food-grade citric acid was added until the pH was bought down to 4.00, then the aliquot placed in an alcohol-sterilised 700mL glass longneck and placed into storage.

The remaining 500mL aliquots were taken and pH-adjusted at random due to overshooting the target pH on a couple of occasions:
aliquots w/ pH 6.0, 6.5 and 7.5 contain higher traces of sodium and citric due to the target pH being overshot, <= 8.5, and needing titration (a fishy odour was observed when the pH was brought too high);
aliquot w/ pH 6.5 only contained 400mL due to losses by evaporation of the mother liquor, it was the last one allocated.

By the time I'd gotten to the the 8th/last aliquot the temp had dropped quite a bit and I noticed the reading for the untitrated dunder was now reading 3.88 so I will let all the glass bottles come to room temp then do a final correction where need be.

Seeing as there would be very few fermentable sugars leftover in the dunder I'm thinking I'll replicate the above experiment using fresh, dilute molasses.

As for a control I'm thinking that maybe some dilute invert sugar syrup in a similar fashion as described above.

Waddayathunk? :-B

* This dunder had in fact spontaneously refermented which had gone on unnoticed for about a month when, to my surprise, I went to take the 2 inch round metal cap off of the 50L keg it was contained in and noticed a hissing sound. Neat, I thought, until I loosened the cap a little more, and little more, until a fucking loud pop sound erupted and the little stainless steel cap went shooting right past my face and crashing into the tin roof above me. Quite a close call, I wasn't all that phased though, more excited about the random spontaneous fermentation from old backset-dunder.

[scythe]

Interesting hypothesis, i wonder if there are any nasty yeasts that might fly in?
My guess would be that the mid range of your pH sample will be preferred by wild yeasts much like commercial ones.
Would containers with larger openings have been more suitable test vessels to "catch" the little yeasties?
Will be interesting to see what actually turns up in your bottles.

[RumFiend]

Interesting hypothesis, i wonder if there are any nasty yeasts that might fly in?

By having a variety of environments at varying pH levels I'm providing desirable conditions for some organisms and not-so-desirable conditions for others. There may be a high level of nasties in some bottles and a high level of favourable yeasts in others, either way I'll have a rough idea of which organisms like which conditions and can tailor my future open-air dunders to favour the wild yeasts I'm after. From there I could even isolate the organisms I've after but thats a whooole lotta 'nother kettle of fish work ;-)

My guess would be that the mid range of your pH sample will be preferred by wild yeasts much like commercial ones.

Thats my guess too. However, certain bacteria also like this pH range too so if they can beat the yeast to the chase they'll have a foothold on the dunder and do whatever they like to it. One thing to keep in mind is that because this experiment is basically a co-culturing of an unknown quantity of organisms there is room for quite a lot of growth dynamics to come into play.

For example, lets say 'bacteria A' is a quick coloniser and producer of acids, and 'yeast B' is a slow-grower that ferments acid into alcohol. Bacteria A might take over the dunder quite aggressively at first leaving no chance of other organisms taking hold while it pumps out acids. At some point this bacteria might produce so much acid that it can no longer survie.
Enter stage-left yeast B, who loves acid and can now thrive in the environment bacteria A has set up for it. It inoculates the dunder quite quickly, consuming all the acid left by bacteria B, and as a result producing alcohol and CO2.
This could go on and on with flux of conditions being created and consumed by various bacteria, yeasts and whatever else. My example is a very simple one but you get the idea.

Would containers with larger openings have been more suitable test vessels to "catch" the little yeasties?
Will be interesting to see what actually turns up in your bottles.

Yup, I would've preferred open jars but I'd just scored a few crates of relatively clean long-necks so I thought fuck it, why not use those instead.

I'll be sure to post as many filthy spore-ridden disguisting mould shit pictures as possbile :happy-partydance:

[RumFiend]

Attached is a paper that describes the positive impact on wine profile by two yeast strains, C. candida and S. cerevisiae.

[RumFiend]

The containers were corrected today to within 0.02 pH at a temp of +/- 22C. Quite a few of them were quite a fair way out, nearly 0.5 on some. I'd forgotten that pH varies quite a bit at higher temps (something to do with concentration of hydrogen ions?).

A magnetic stirrer was indispensable in dissolving the caustic soda and citric acid much quicker, smoother, and predictably.

I put the containers in my big backyard, near my cactus garden. There's heaps of trees where I live (well, for a suburb anyway) so that should provide some nice pollen floating around, plus watering the garden kicks up a bit of dirt into the air, we've got a few animals around too; all this and more should contribute to a fairly decent and unique microbiota :happy-partydance:

Fingers crossed!

[RumFiend]

pH 4.0: no visible signs of growth
pH 4.5: thin, uniform layer of smooth growth covering entire liquid surface.
pH 5.0: partial layer of growth similar to 4.5 covering about 25% of surface.
pH 5.5: no visible signs of growth
pH 6.0: blotchy, smooth growth covering entire liquid surface, slight 'bedsheet wrinkles'
pH 6.5: same as 6.0
pH 7.0: very thick crust of smooth, fuzzy growth covering entire surface, this sample has been infected the most.
pH 7.5: very thin, smooth layer of growth covering 50% of liquid surface.

All growth appears white in colour.
All samples smelt the same: just like fresh dunder; the exception being pH 7.0 which smelt noticeably sweeter and fruitier.

[Urrazeb]

Interesting :think:
Thanks for the update

[RumFiend]

Well it's been quite a while since I've posted any updates. In that time, the bottles have seen many cycles of various stages of growth but all of those growths appear to be quite common in appearance. The difference among them all seems to be how far advanced into a growth cycle the organism is and therefore how intricate the stuff is thats growing on top of the dunder.

Again, due to the shape and colour of the bottles its hard to take accurate pictures. It's been raining a lot lately so most of what's grown on the liquid surface has been dissolved back into the dunder.

A smell test is also well overdue.. yummy..

This experiment may be moving soon (geographically) so it'll be interesting to see what changes take effect in their next home.

[RumFiend]

TODO:
1. smell tests
2. take pictures
3. measure pH


I can't think of what else to test/measure. suggestions anyone?

[Hawkeye]

Specific gravity? If you're experimenting with wild yeast, the aim is still alcohol production, SG might give you an idea...

Have you read Sandor Katz book called The Art of Wild Fermentation? Discusses how wild yeasts have been used by civilisations through history. Really interesting book and shows how they used to do it without all the commercial yeast strains we have now.

[Rush006]

Is it wild yeast or bacteria your testing? Im sure there is probably both in your test bottles. Im very interested in starting a dunder pit. at this stage I'm still in the read up and study phase. lots of good info on this forum and a few other international sites. thanks for posting your experiment

[RumFiend]

Specific gravity? If you're experimenting with wild yeast, the aim is still alcohol production, SG might give you an idea...

Have you read Sandor Katz book called The Art of Wild Fermentation? Discusses how wild yeasts have been used by civilisations through history. Really interesting book and shows how they used to do it without all the commercial yeast strains we have now.

Hey Hawkeye, thanks for replying. No I haven't read Katz's book, it sounds pretty interesting though. Humans have yeast in all kinds of intriguing ways since the dawn of time, as you no doubt know, so anything along those lines is bound to pique my interest. Thanks for the heads up.

As for for SG unfortunately I didnt take any readings at the time. Alcohol production wasn't part of the aim in this experiment, rather the effect of differing pH levels on the microbiome that took hold of each bottle and the resultant 'flavour soup.'
Rum is indeed the name of the overarching game, however in this case I'm more concerned with the dunder aspect, which from my research does not necessarily indicate alcohol production. Some texts I've read inform me that the dunder was simply an additive at the time of distillation and not even a part of the fermentation at all, which goes against what a lot of people on the internet seem to think. Having said that, dunder usage isn't exclusive to either process.

[RumFiend]

Is it wild yeast or bacteria your testing? Im sure there is probably both in your test bottles. Im very interested in starting a dunder pit. at this stage I'm still in the read up and study phase. lots of good info on this forum and a few other international sites. thanks for posting your experiment

You're right Rush006, it would be a mixture of both. If I were to end up with a desirable 'nose' profile on one of the batches I'd probably look into isolating some of the yeast(s) and or bacteria present, to see if there were a single organism that was responsible for significantly producing to the overall desirable properties.

I'd like to start this experiment again with clear bottles and monitor the growth more closely and consistently next time. There may be a point in time for a particular batch where there is an ideal flavour profile. What I've noticed with the current experiment is that the 'soup' is always in flux, so there is a fair degree of entropy to each mixture, i.e. there's a whole lot of variation going on! It would help the experiment if I paid closer attention to this :)

[Rush006]

Ive had really good results with aged Dunder up to about 30 days old.(which consolidates one of the articles i read on Dunder). now my Pits are getting really funky the results have not been consistent. they might just take some time to settle down after the 30 day stage. ill keep testing and searching for that perfect flavour. am only adding Dunder to boiler for a little while to confirm a few things with age. Gee I love this distilling. just wish i concentrated more in chemistry at school. Ha Ha. :laughing-rolling:

[P3T3rPan]

You must have a long tongue if you can taste your pits.
"How does he get all those girls?"
"Fucked if I know, he just stands there licking his eyebrows"

[RumFiend]

I just did a few quick whiffs of the bottles and there's quite a spread of different smells going on. some interesting, some dull, one in particular smells highly of vomit so I'm going to assume for now that there's higher levels of butyric acid in that one.