Yeast Starter FG

[mattjm]

I made a yeast starter (Danish Lager) about 36hrs ago and it has been fermenting away on my stirplate since. I made the starter with LDME 2L to 1.040 and it is currently sitting at about 1.020 (refrac correction from 1.035). The smack pack did not swell very much at all in the approx 3 hours I gave it before pitching. Is the yeast a bit sluggish or is this about normal. I want to brew tomorrow so I was planning to refrigerate today and decant prior to pitching. Is it safe to say I have had enough yeast growth or should I let it carry on a little longer. Perth temps are finally starting to cool (10-19) and this is spinning away in the kitchen.

 

[Ducatiboy stu]

Wont hurt to change the wort

Go with a 1020sg starter

 

[MHB]

Should finish about the same as an equivalent beer, so I would be expecting 1.010-1.012 depending on your DME.
Not really a surprise that a smack pack takes a bit longer to swell, if they are day old they can pop up pretty fast, as they get older they slow down, if they come strait out of the fridge they can take an hour or more to warm up enough for the yeast to fire.
You really don't need to smack them, you can just add then to the starter, make sure there isn't too much difference between the temperature of the yeast and starter or thermal shock can kill a lot of yeast.
Mark

 

[danestead]

Sounds normal to me. Only small lager starters with a really fresh pitch of yeast would be done in 36hrs.

You don't need to test the fg. Just wait until the small co2 bubbles have stopped rising then switch the stir plate off, leave for 8hrs then chill in the fridge.

 

[mattjm]

Im not really seeing any action, so the consensus is let it go longer?
I cooled the starter wort to about equilibrium with my tap water then pitched the yeast that had been out of the fridge for 3 hours so i dont think thermal shock was an issue.

 

[manticle]

Lack of visible action in a starter is not a guarantee of inactivity.
As you said - gravity has reduced and further resuction is the only way to tell (although tiny bubbles when held up to the light can be a subtle visual indicator).

 

[mattjm]

I definitely have activity I looked closer and there is clearly tiny bubbles rising to the top.

 

[manticle]

I'd say all good and some zen patience is required.

 

[mattjm]

So I'm going to basically wait till that subsides before cold crashing, as I am looking for yeast growth not complete attenuation I wasn't sure whether I actually need to achieve a full and finished fermentation prior to pitching

 

[Ducatiboy stu]

You might be better to draw the active yeast off at high krausen and adding new wort rather than waitng for it to finish

 

[danestead]

So I'm going to basically wait till that subsides before cold crashing, as I am looking for yeast growth not complete attenuation I wasn't sure whether I actually need to achieve a full and finished fermentation prior to pitching

Well there is 2 ways to go about doing starters. Either waiting for them to finish, chill, decant then pitch, or pitching the whole starter into your fermenter at high krausen. High krausen is the peak of the starter fermentation and most of the yeast growth has taken place. It is only recommended to pitch the whole starter if the volume is less than about 5% of your batch size.

 

[manticle]

Or if it's a smaller batch of the same wort, fermented under similar conitions (which is how I do it).

 

[mattjm]

Its closer to 10% and I highly doubt it will finish completely by tomorrow although it may go close, but Id be doing well to have time to finish it and have it ccing by tonight so I can decant and pitch tomorrow. Best I can do is take it off the stir plate tomorrow and decant half of the wort prior to pitching. I certainly thought this step was a bit more straight forward then it seems now. Oh well more learning I guess and next time start my starter more than three days out maybe tuesday for a Sunday brew instead of Thurs.

 

[mattjm]

Would 2L of this starter 1.040 LDME be detrimental to an Pills lager? Should I just pitch the lot?

 

[Ducatiboy stu]

Once you have pitched the yeast into your beer, draw out 1-2ltrs thru the tap at peak krausen and use this as the starter of your next batch.

You can do this for any beer, Obviously you wouldnt take a starter from a stout and use it in a pale ale

 

[mattjm]

I assume you mean if you are ready to brew straight away? If you wait for high krausen wouldnt the wort you are pulling off be useless for a starter wort? Im a bit confused by what you mean?

 

[Ducatiboy stu]

It can sit in the fridge. Just let it warm up before pitching

 

[mattjm]

so you talking about repitching the yest slurry, I have a sight glass at the bottom of my conical and I plan to drop the first trub then collect the yeast once it settles in the sightglass so basically the same thing but I will only collect about 300mls and build it up again in a new starter.

 

[Ducatiboy stu]

No, not re pitching slurry, but drawing off yeast when it is at its most active in the ferment

 

[mattjm]

My starter has dropped to 1.009 so I have turned off the stir plate and will allow the yeast to drop out and hopefully be able to decant the liquid off before Im ready to decant.