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General Category => Yeast and Fermentation => Topic started by: benamcg on January 29, 2011, 02:22:15 AM

Title: Is My Washed Yeast Too Old
Post by: benamcg on January 29, 2011, 02:22:15 AM
Went to make a 2 L starter tonight with washed yeast.  I didnt think about it until I pulled it out of the fridge, but the yeast washed on Dec 4th.  I have 800 mL of nice looking yeast, but according to Mr Malty, I am way short (by about 1200 mL).  I placed it in the starter beaker (on a stir plate) and less than an hour in, got some nice frothy head and good airlock activity (could this solely be from the stir plate?). 

I have about 24 hrs before pitching, and I dont have anymore DME to make another starter.

1) Do I pitch it anyway (and hope for the best)


2) Add non starter (or started) yeast from yeast washed last weekend to the cooled wort?

I am leaning towards pitching the older washed yeast anyway, and if the activity is not great (within 4-6 hrs.) , pitching the back-up non-starter yeast.

Any thoughts would be appreciated. 
Title: Re: Is My Washed Yeast Too Old
Post by: Hokerer on January 29, 2011, 02:31:20 AM
The plan you're leaning towards is probably your best bet.  In fact, you might even want to wait longer before giving up on the older yeast.

One thing you might want to change in the future.  The point of a stirplate is to increase the amount of oxygen dissolved into the starter wort.  The vortex continuously refreshes/replaces the oxygen that is consumed by the yeast reproduction.  The vortex gets this oxygen from the air.  Since the purpose of an airlock is to only allow airflow OUT of the flask, the vortex has no place to get oxygen from so you're defeating the purpose/benefit of a stirplate.

Next time, don't use an airlock.  The simplest thing is to loosely cover the top of the flask with aluminum foil.  If you're really paranoid, you can use a foam stopper (like is available from Northern Brewer) instead.
Title: Re: Is My Washed Yeast Too Old
Post by: benamcg on January 29, 2011, 02:34:29 AM
Thanks for the advice- I do have a foam stopper and will now be using it. 
Title: Re: Is My Washed Yeast Too Old
Post by: sharg54 on February 04, 2011, 07:54:17 AM
I don't use a stirplate so can't say much about that  but I have used plenty of washed yeast in the past. As long as it's 3 generations or newer and you kept a close eye on sanitation and storage when you collected it it shouldn't be a problem. I have gone as far as 4 generations with White Labs yeast and three months old with out a problem. If you run out of DME to keep your starter building you can always pull off some of your wort to do the job as well. Just make sure you sanitize everything you use to collect the wort and it will also help your yeast get used to what it's going to work on.  Sort of like a snack before the big feed.