Dunder: surface growth and vinegar smell

[Denizh]

I collected the dunder from my stripping run two weeks ago and kept it indoors in my distilling room. Last week there was a fuzzy spot on top and still smelled of dunder, this week the growth covers the surface and smells mostly of vinegar.

This is absolutely the first time I am doing this and wondering if I am on the right path to establishing a muck jar.

[Denizh]

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[Single Malt Yinzer]

Vinegar: It's because there was still alcohol in the wash. If you leave dunder uncovered then acetobacter will eventually grow and turn the alcohol into vinegar.

Surface growth: There was probably sugar left in the wash. If so then other bacteria, yeast, or mold will grow quickly. It happens eventually as yeast can't use more complex sugars that other microbes can.

The key is the smell - if it smells musty dump it. Mold is bad. Bacteria & other yeasts are ok. To maintain it you can dump most of the dunder on a regular basis and replace it with fresh backset.

[Denizh]

Vinegar: It's because there was still alcohol in the wash. If you leave dunder uncovered then acetobacter will eventually grow and turn the alcohol into vinegar.

Surface growth: There was probably sugar left in the wash. If so then other bacteria, yeast, or mold will grow quickly. It happens eventually as yeast can't use more complex sugars that other microbes can.

The key is the smell - if it smells musty dump it. Mold is bad. Bacteria & other yeasts are ok. To maintain it you can dump most of the dunder on a regular basis and replace it with fresh backset.

Interesting, tomorrow I am planning to distill a rum wash I have been fermenting. The critical question for me is: should I use this dunder to mix with my low wines or use fresh dunder from my stripping run?

Just trying to understand if I am on the right path if I plan to use this dunder for my spirit runs.

[Tummydoc]

I'd use your funky dunder. For ester formation you need acid, so the vinegar isn't a bad thing. Its all trial and error, but I'd give it a try.

[Single Malt Yinzer]

Like Tummydoc said it's trial and error. Trust your nose. If it smells musty then don't. Other aromas that are sweet or odd should be fine. The distilling and aging process will turn those chemicals into something else, normally good. Esterification is kinda crazy and not easily predictable. That's some of the fun. Use a small amount and then use more until you develop your nose and experience.

[howie]

like a proud dad lol
picture of my first dunder pit
midday today it was only the white rings at the side, 7pm it has grown to this.
it's about 5l of dunder from about 2 months ago.
kept hygienically in a cube until sunday, when it was thrown into a pail with a pot of yakult, with sunshade strapped over the top of the pail.

i can't work out if it's trying to tell me something?
is that an arse or a big pair of breasts in the top?

[Yummyrum]

You've been reading too many tea-leaves Howie

Its clearly a cute little furry creature .

40401FA8-370F-43E7-8ABC-9E6F3BC64240.jpeg (6 KiB) Viewed 1625 times

[Tummydoc]

That's ass, take it from a trained professional!

[Denizh]

OK, so I had placed one of the gallon jars outside (in about 15C temperatures) and the other one indoors (20C temps). Take a look at the attached photos, the one woth the pellicle was kept indoors.

They both have a similar acidic vinegary smell with the pellicled one being stronger.

[IMG]https://uploads.tapatalk-cdn.com/202102 ... ebd28a.jpg[/IMG]
[IMG]https://uploads.tapatalk-cdn.com/202102 ... 3ebe8e.jpg[/IMG]

[howie]

latest pic of dunder (not the planet mars!!!)
seems like an interesting selection growing in there
took the shade cloth off today, and there were about 6 fruit flys in a hurry to get out.
no idea how they got in.
does it look ok?