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I'm getting to be a fairly experienced brewer now but this is my first experiment with sours. I read about using lactobacillus from yoghurt so I thought I'd give it a bash.

The process so far... Simple all-grain mash, OG around 1.047. Sparged, raised to 80oC to pasteurise, then chilled to 30oC. Placed in a sanitised demijohn leaving the smallest possible air gap at the top. Just shy of 5 litres in total. Popped a bubble trap on then wrapped it with a heating belt to maintain 35oC. I cannot rule out the presence of oxygen.

I pitched in a 65ml pot of Yakult live yoghurt that apparently contains 6.5 billion lactobacillus casei.

After 12-18 hours there seemed to be gaseous fermentation going on - bubbles rising and a sort of small krausen formed. This puzzled me because I thought casei was homofermentative.

I couldn't resist popping out the bubble trap and having a sniff of the fermentation. Oh dear... I wish I hadn't done that. I was expecting to smell the beginnings of souring... What I actually smelt was an affront to my nostrils... The sort of smell that makes you pull away. Fetid, perhaps slightly fecal, or dead vegetation.

The fermentation appeared to stop after around 30 hours but the smell is still unpleasant. The gravity is still way up near 1.047 so if fermentation as I understand it took place there wasn't much action.

I have risked tasting the product and there is definitely some sourness there, but it's hard to get past the smell.

I'm now in day 3 and the demijohn is just sitting there looking completely inactive... So I sit and wait. It's around pH 3.5.

My plan is to boil the soured wort to drop the break out and kill the lacto, add some late addition hops, and then pitch saccharomyces as normal.

So I guess my questions are...

What is that smell, and is it normal? Will the smell disappear? Will the boil get rid of the smell? If I wasn't going to boil it would be smell disappear? Why did it appear to ferment?

Thanks already for your help! :)

/* EDIT */

I boiled it today, about 3.5 days (80 hours) after first pitch the lactobacillus. There's a strong sourness on the palate but it's not lip-puckering. No bittering hops so it was just a quick 45 minutes boil.

The nasty smell certainly mellowed but didn't disappear completely. It's no longer overpoweringly unpleasant but now just a funky 'note' of the aroma profile.

Steeped 30g First Gold whilst I was chilling it back into a different, sanitised demijohn. Pitched a stack of Nottingham dried for a nice quick fermentation.

/* EDIT */

OK - fermentation over. FG dropped to 1.011 - ABV 4.3%. That hideous smell has mellowed a lot but not completely disappeared. It is still detectable but not unpleasant.

Bottled a week ago but couldn't resist popping a bottle today. Obviously carbonation is poor but it's a lovely refreshing sharpness. On the whole, very pleased. I'll be trying this again.

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  • I don't think it's normal. I fermented many things (but not wort) with bacteria from yogurt and kefir and never got anything like this. I'd guess an infection - but I admit it's just a guess based on unrelated cooking experiments.
    – Mołot
    Commented Mar 3, 2016 at 22:04
  • Although I won't rule an infection out, I'd be surprised if it was. It's quite easy to control the infection when brewing on such a small scale. I'm not using excessive amounts of equipment so the potential sources of infection are pretty minimal.
    – Doug
    Commented Mar 3, 2016 at 22:39
  • I hope you're right. I'm just saying my sourdough never had any hint of such smells. And it was grain, water and yogurt or kefir. But maybe it's something different in wort. That's why I don't feel competent to post an answer.
    – Mołot
    Commented Mar 3, 2016 at 22:44

3 Answers 3

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Addressing your homefermentative comment, how do you know this Yakult pitch is a single strain of microbes? It could have some other strains to a smaller % and they are giving you your off smell. There isn't much regulation in the purity of yogurt cultures. Its more of a what is the largest population pitched to make the product. It doesn't mean there aren't other microbes coming along for the ride.

The only answer is to let it go through your process and see what you get. Its an experiment really.

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  • You're absolutely right. There's no guarantee that it's only L. Cases in Yakult so there could easily be other beasties in there.
    – Doug
    Commented Mar 4, 2016 at 15:31
  • Interestingly, it wasn't fermentation as you'd understand it - it lasted only a few hours and stopped without perceptibly reducing the gravity.
    – Doug
    Commented Mar 4, 2016 at 15:33
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Have others soured using Yakult?

From what I can tell it's a specific strain of Lactobacillus (casei Shirota). Specifically designed as a probiotic to aid digestion.

Kinda makes sense it would smell septic.

I would say boil it and see how it turns out. I've had many great beers where fermentation smelled terrible.

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  • That's reassuring. I was probably going to try that anyway. :)
    – Doug
    Commented Mar 4, 2016 at 8:26
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Although we use acidulated malt kettle sour, we too always get an off putting smell during kettle souring boil does rid most or atleast some of the smell, but fermentation does the best job of getting rid of the smell assuming we have the same nose... Does it smell similar to nuts and old yogurt? If so you have a good start and not to worry it will be fine. If it smells more like baby poop like actual bad diaper like you want to throw it away then see what happens in fermentation if doesn't get rid of the smell then yes it is abnormal.

Brandon J. Woodruff Founding Brewer Mancave Brewing Company Eugene, OR

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