Save or dump this very active yeast starter?

Made a 1600 ml yeast starter using a 2000 ml flask . Sometime during the night the krausen was pushed up through the neck and pushed out the foam stopper to spill over the edges. Thus, since this strong activity resulted in the starter being exposed to the external air I am wondering if I should keep the yeast from this starter? My concerns are will there be much yeast remaining in the starter since this was a top cropping yeast strain and could airbourne yeast create a problem for this starter.

Hmmm, never heard of this happening but if it were me I would still use the starter. The reasoning is that if the yeast did blow out then any contaminted yeast is already out of the starter. A by product of fermentation is co2. The co2 is constently pushing up the neck of the flask and any floaties in the ambient air will also be blown away by the co2 current. This is how breweries do open fermentation.

I'm not saying your starter isn't contaminated but I'm saying the probability is low. Also, have you considered putting foil on top of your flask? This allows co2 out and oxygen in without a build up of pressure to cause a blowout.

I'll try foil next time I am near full capcaity for the flask. Thanks for your input and suggestion.

If this were me I'd still use it. Just like Arnold said, the CO2 will have the tendency to push any contaminants out.

msa8967 said:

Thus, since this strong activity resulted in the starter being exposed to the external air

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I'm no expert but this is what you want with a starter isn't it? The yeast are supposed to be taking in as much oxygen as possible to reproduce. If it were me, I would toss anything that made it outside of the jar and use the rest of the starter.

Just curious, when were you planning on pitching? If you have the time, maybe let it go for another few days and then see if you detect and funky smells.

I will be using it early next week so letting this go an extra day or two would be fine.

It should be fine to use.

I suggest to cover starters with foil and to add 1 drop of fermcap-S to minimize krausen height.

It should be fine to use.

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I agree w/ you. I would use foil from now on for your starters. At least you know the yeast is healthy!

I've had foam stoppers pushed out before, but I had a lot of gnats around so tossed it.

+1 to foil on top of the flask. I've never had any problems using it and I do 1.5L starters in a 2L flask.