Testing stored yeast for possible infections

Over the past year I have built up a large yeast bank by making double starters (one to pitch and one to step up) and then using the last runnings from the mashtun to step up build a new starter.For the last batch of yeast I have raised (WL001) I had 3 infections from 6 different brews. Since some of the yeast pitched came from a common sealed jar I am not sure if the infections came from the yeast or from the buckets. This happened with 15 gallon batches with 3 separate buckets for each batch. I tossed the beer and bleached the buckets. I tossed out all of the WL001 yeast I has stored.

Now I want to test my other stored yeast strains for potential infections. I was thinking of trying to make a 1/2 gallon starter for each jar and then let the yeast starter go for 1-2 days. After that I will seal the gallon jars and then either place the yeast in my lagering fridge or leave out for a period of time to see if there are any crazy bugs in it. Not sure if leaving it out or placing in the fridge will give me better results. Any thoughts on this or something else I could try?

 

I can't add anything valuable, but I would imagine leaving the sample out vs in the fridge would be better. The colder environment will just slow down the bugs from taking over, if the sample is infected.


Best of luck. Look forward to your results, as I have a small bank of yeast I try to maintain.

 

OK...I will let these go for 2 weeks at room temp. Not sure how this will affect yeast health at the end of the process but better this than to risk future infections. Thanks for the reply.