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Settling Yeast for Decanting

So you've listened to all the advice from your fellow brewers about making a yeast starter.

Heck, you've made a great starter. You've swirled and mixed this starter everytime you laid eyes on it. Maybe you went on Ebay, Labx or Cynamr and found yourself a stir plate so you could have even better growth (A 4-10 fold increase interests you doesn't it? Makes $20-40 spent seem well worth it).
Now here's the problem though, you went and tasted the starter. Egads, oxidized foul tasting brew. Do you really want to throw that nasty stuff into your nice clean pristine beer?
If you've got a day, you can force settle your yeast in the fridge. To see what happens over the course of a day, I present a little slide show of a day in the life. Make sure that before you use the yeast, you decant the starter and feed the slurry with a bit of wort to wake it back up and to stir the yeast back into solution in time for pitching.
  0 Hour of Settling

2 Hours of Settling

10 Hours of Settling

24 Hours of Settling

At the end of 24 hours the yeast cake has nicely compacted down, with the wort clearing above the sediment line. Now all that remains is to pour off the spent wort and reinvigorate it in time for the brew day

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justin_bourret's picture

What is the best way to reinvigorate the yeast starter after you've decanted the spent wort?

Administrator's picture

a little fresh wort never hurts, but in reality you can take it straight into a beer no problem.

MrDouglasN's picture

How long can a starter sit in a fridge after cold crashing? Should it be stored with the starter wort still in the flask or decanted? I vaguely remember hearing something about the yeast using up their glycogen reserves fairly fast...


rdexter's picture

It seems like dumping the whole thing in while the yeast are active and already munching would be the best way to get the fermentation rolling.  The sooner the fermentation gets going, the less chance of bad stuff taking over.  But there is the issue of all the wort in the starter that is just going to dilute your beer.  Especially if it's a big starter.  So I can see the advantage of doing this process.  Now the yeast will be added while it is still somewhat sleepy.  How does this affect the fermentation?  To reinvigorate you mention adding some wort.  I suppose I could add some wort of the beer I am making from the sample valve of my conical after or as I am filling it from the kettle.  How long would should I let the yeast invigorate after adding wort before I pitch it?  Or do I just add enough to loosen it up to make it pourable and just dump it?

Drew Beechum's picture

I'm not really worried about lag times. I tend to think the speed race to start fermentation faster isn't a terribly good one. Sanitation and a large pitch of slurry along with cooler temps will cause a longer lag, but I think give a cleaner beer particularly without all the oxidized starter wort. So I settle and decant. If I'm refreshing the slurry, I'll usually take just a pint or two of the freshly chilled wort and toss it in while the rest of the beer is chilling down. Let it rest for 10-20 minutes and you're good to go.

rdexter's picture

Ok, cool.  Sounds like a plan.  I'll try this on a repeat of a batch I did using a full 3 liter starter and compare.


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