Black Mould on a Vial

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Mrobson

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I’ve had a vial of yeast in the fridge for a few months and finally got round to using it. I boiled some light DME for the starter and when I opened the vial to pitch I noticed the lid was full of black mould and smelled of what I can only describe as wet wood. With nothing to loose I wiped away what I could from the top of vial, gave it a good shake with my starsan’ed finger over the top and pitched it anyway.

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The starter seems very dark to me which is making me worried. I’ve got a cherry stout planned for the weekend, what’s the chances that the yeast is going to be usable or is it down to the beer gods? Would I be stupid to take the risk?

Cheers

Edit - it’s a proper Kveik strain, not an isolate
 
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the baron

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Not a yeast expert but doesn't look good to me I am sure the yeast masters will comment
 

Mrobson

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Ye that’s what I was thinking too, going to let it ferment out anyway

Cheers
 

Mrobson

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I left this to ferment out and have the slurry drying in the spare room. I tasted the starter and couldn’t taste anything out of the ordinary, given it was only a few days old tho. Would a spell in the freezer kill whatever the black mould was or would making a batch with this yeast still be a gamble?
 

An Ankoù

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Ditch it. It's more likely than not that it'll ruin your beer.
You can wash yeast with a chemical to kill the non yeasts. Forgotten the name.
I think BeerCat's referring to acid washing, which, I think, uses phosphoric acid to get rid of bacteria. Probably doesn't work with moulds.

Have you got any bottles of the beer you originally used that yeast for? You could make a starter up from the sediment.
 

BeerCat

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Ditch it. It's more likely than not that it'll ruin your beer.

I think BeerCat's referring to acid washing, which, I think, uses phosphoric acid to get rid of bacteria. Probably doesn't work with moulds.

Have you got any bottles of the beer you originally used that yeast for? You could make a starter up from the sediment.
Yes your right been reading up on it. Interesting topic. I would dump the yeast and buy more.
 

Mrobson

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From what I’ve read mould can be quite resilient.

The yeast discussed in this topic in Espe, would anyone be up for a yeast swap? I’ve got both dried and slurry of the kveik strains I’ve currently got.
 
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