Bad Sulfur Smell = Bad Yeast?

[ultravista]

I pulled a few jars of Pacman yeast from my last brew. The yeast jars sat at room temperature (approx 75f) for approximately 1 week.

The once clear top fluid turned hazy, and when opening the jar, gave off a sulfur smell. All three jars went cloudy and had a similar smell.

I poured off the liquid, filled the jars with distilled water, decanted the slurries into a larger jar and refrigerated.

I am assuming the warm temperatures had something to do with the cloudiness and smell. It was almost like it started fermenting again; maybe yeast consuming yeast.

Is this yeast bad now?

Should I toss it and mark it as a lesson learned?

 

[Calder]

I'm sure you have heard of autolysis; now you know what it is.

Next time store the yeast in the fridge. The same thing will happen to it, but it will take 6 months rather than 1 week.

The good news is that you don't have to toss it away. Decanting the liquid was the right thing to do. Make a 1 liter starter, and let it ferment out. Place it in the fridge for 15 to 30 minutes to let most of the dead cells drop, pour the liquid into another container, leaving the sediment behind. Make another starter with the liquid, and then use.

The dead yeast is actually a nutrient for the live yeast, but personally, I would not want to put that many dead cells into fresh new wort. I would be concerned about that nasty smell carrying over (probably not a concern, but I just couldn't do it).

 

[ultravista]

Calder - the smell diminishes with each washing but it is still very pronounced.

Are you suggesting a starter to rejuvinate / build the good yeast? Will that drive off the smell?

 

[Calder]

Make a starter to build up the good yeast.

Wash the yeast - Cold crash the starter (for about 15 minutes) to drop the dead yeast and pour off and save the liquid.

Cold crash the liquid again, until clear. Pour off the liquid and save the sediment.

Make starter as normal with the saved yeast.

 

[SickTransitMundus]

Pacman slurry should have a slight sulfide odor, but you are describing something worse. In any case I agree with Calder - wash it, make a new starter, and see if it improves.