Mother of vinegar to sour stout?

[BorealBrewer]

Hey, HBT!

I'm planning a couple one gallon stouts in the next few weeks. I've read about getting the distinctive Guinness-style "twang" by deliberately spoiling a bottle or two of stout, boiling it, and adding it back to the brew in secondary.

Would deliberately adding mother of vinegar to a poured bottle work? Am I after a different organism than the mother of vinegar? Has anyone tried this, and, if so, what was the result?

Any info is greatly appreciated!

 

[Gavagai]

You need lactic acid bacteria. Mother of vinegar makes acetic acid.

You could try adding a spoonful of malt to a bottle, top it off with a bit of your (unaerated) unfermented stout wort and put a balloon on top (ghetto airlock), then keep it in a warm place for a few days. The less oxygen available, the more you'll favor lactic acid over acetic acid. It will be much easier to sour wort than beer.

 

[BorealBrewer]

Hmmm. I wasn't sure if I was after lactic acid bacteria or acetic - this is why I asked, and why I love this forum!

I'm going to try the malt-wort set-up. In another bottle, under identical conditions, I'm going to try inoculate a mesophilic lactic bacteria cheese culture, and see what happens.

Thoughts?

 

[Gavagai]

Sounds like a fun experiment. The strains in cheese cultures are not the same as those found in sour beer (those would be l. delbruckii and l. brevis), so I assume they aren't alcohol tolerant, but if you're adding them to unfermented wort it just might work!

Although there's also the antibacterial properties of hops to consider...

 

[BorealBrewer]

I just found the "what goes in beer" post on your blog - nice work!

I actually have an l. brevis culture with my cheesemaking supplies - just found a site that suggests it's particularly hop-resistant, and is seen as a major beer-spoilage organism. I knew that even with good sanitation, it was dodgy to try make beer and cheese/sauerkraut in the same room on the same day...

I think that experimental condition #3 will be some wort inoculated with the juice from a particularly nice jar of 'kraut.

 

[Gavagai]

Cool, let us know how it turns out!

 

[rayfound]

The vinegar culture eats alcohol i think...

 

[BorealBrewer]

Yup, the vinegar culture does eat the alcohol, which is why I thought initially about inoculating some finished stout with it, getting it soured, boiling it to kill the acetobacteria, and denature any ethanol-to-acetic enzymes that might be left, and adding it back to the stout.

I'm not sure if the mother of vinegar can act directly on wort, or not...in this case, though, the mother of vinegar comes from a batch of wine that turned (never get more grapes than you can actually handle, lesson learned!) so should have some sort of yeast present.

I'm going to start tonight. I imagine the turn-around time on this series of tests should be pretty quick - at least for initial, it's-sour-or-it's-not results. Keep the ideas coming, folks, I'll post results when I have 'em!