WLP007- Contaminated?

[MG1602]

I recently grew up a starter from a slant that finally went to 2.5L of wort. This is the second time to use the yeast, and don't remember it acting this way last time. After 24H on stir plate, I stopped and let it settle for 12H before crashing(usual protocol). One thing I noticed is that tiny yeast droplets were coming to the surface after the twelve hours. It has the bready smell, and an ever so subtle twang, almost sour? 82% efficiency, so this is par for this yeast. Has anyone had this experience with WLP007? My gut is telling me to toss and start over. Feedback is greatly appreciated.

 

[CBMbrewer]

Seems suspicious. How old is the yeast? Did you harvest from a higher gravity beer?

 

[MG1602]

Not too old. Slant was about a month old from a plate that was about 2 months old. Clean colony pick.

 

[CBMbrewer]

My concern would be if it came from a high gravity beer. That can cause cell death and mutation that can certainly cause less then normal aromas.

 

[MG1602]

Sorry, just saw I said efficiency. I meant attenuation:smack:

 

[MG1602]

The weird thing is the yeast droplets. I don't believe I have ever seen that? I am assuming it is C02 still being pushed out, but this also means some fermentation is going on. The yeast cake had already settled though!