Black Mould on a Vial

[Mrobson]

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.

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

 

[The Baron]

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

 

[MyQul]

I REALLY wouldnt be happy with that and deffo wouldn't pitch the starter into a batch

 

[the_quick]

Better be save than sorry and ditch that starter. You risk the whole batch to go bad.

 

[Mrobson]

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

Cheers

 

[Mrobson]

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?

 

[BeerCat]

You can wash yeast with a chemical to kill the non yeasts. Forgotten the name.

 

[An Ankoù]

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]

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]

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.