Infection in Stored Yeast/Yeast Viability

[MrZuckerkorn]

So I'm planning to brew a couple of batches next weekend, a saison and an IPA. I have saved yeast in the fridge for each batch (wyeast 3711 and 1056) harvested from overbuilt starters. I made a new starter this afternoon, but when I opened my 3711 jar the contents started lightly fizzing, almost like I had poured an undercarbonated beer. The fizzing continued, coming from the yeast at the bottom, and was knocking some chunks of yeast free, floating them to the surface. When I lifted the jar to try and decant some of the liquid, the movement made much more of the yeast come loose, mixing and making it impossible to decant. I tasted some of the poured off liquid, it didn't taste infected but it might have had a bit of an off flavor. To me it almost smelled a bit salty, while my wife said it smelled like corn. I sanitized my mason jar by boiling in water along with the lid and ring for 15 minutes, drying upside down on a sanitized surface, and spraying with starsan before putting the yeast slurry inside. I've never had an infection before (17-18 brews now), and have never seen a saved starter do this, they are always completely flat and the 3711 stays in place when I decant normally. Does this sound like an infection? I'd like to avoid buying a new package, but obviously it's not worth ruining a batch over $7.

Also, the 1056 has been in the fridge longer than I thought, since April 22nd, and brewers friend estimates it is 6% viable. Is it really that low if it's been kept refrigerated and undisturbed under a layer of beer (from the starter)? It's probably not worth trying to build a multi-step starter, but if I can get it done in one step in a 2 liter starter on a stirplate that would be great.

Thanks!

 

[55x11]

So I'm planning to brew a couple of batches next weekend, a saison and an IPA. I have saved yeast in the fridge for each batch (wyeast 3711 and 1056) harvested from overbuilt starters. I made a new starter this afternoon, but when I opened my 3711 jar the contents started lightly fizzing, almost like I had poured an undercarbonated beer. The fizzing continued, coming from the yeast at the bottom, and was knocking some chunks of yeast free, floating them to the surface. When I lifted the jar to try and decant some of the liquid, the movement made much more of the yeast come loose, mixing and making it impossible to decant. I tasted some of the poured off liquid, it didn't taste infected but it might have had a bit of an off flavor. To me it almost smelled a bit salty, while my wife said it smelled like corn. I sanitized my mason jar by boiling in water along with the lid and ring for 15 minutes, drying upside down on a sanitized surface, and spraying with starsan before putting the yeast slurry inside. I've never had an infection before (17-18 brews now), and have never seen a saved starter do this, they are always completely flat and the 3711 stays in place when I decant normally. Does this sound like an infection? I'd like to avoid buying a new package, but obviously it's not worth ruining a batch over $7.

Also, the 1056 has been in the fridge longer than I thought, since April 22nd, and brewers friend estimates it is 6% viable. Is it really that low if it's been kept refrigerated and undisturbed under a layer of beer (from the starter)? It's probably not worth trying to build a multi-step starter, but if I can get it done in one step in a 2 liter starter on a stirplate that would be great.

Thanks!

Brewers friend estimate of yeast viability go from 12% at 4 months old, to 3% at 4.5 months old to 0% another 2 days later. Obviously that's not realistic.

It's possible your yeast was just slowly fermenting some residual sugars left in the starter. Or it is wild yeast. Given low viability (it may not be 6%, but probably below 20% for sure) and your suspicions of infection, I would just get a new vial.

 

[MrZuckerkorn]

Thanks, I had similar thoughts about viability. I didn't write very clearly, the possible infection is on the saison yeast, which is actually from the end of July, putting it's viability around 70%. The 1056 is what I've had since April. But, even though the saison yeast is plenty viable, I suppose it's not worth the possibility of infection.