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General Category => Yeast and Fermentation => Topic started by: flbrewer on March 20, 2015, 06:39:33 PM

Title: Cold Crashing Starter
Post by: flbrewer on March 20, 2015, 06:39:33 PM
I need some clarification on when to cold crash a starter please. I believe in the past people have mentioned after the krausen begins to fall. I have read more recently that you should crash after fermentation is over in the starter. Thoughts? Bonus picture below of my starter after 18 or so hours.

(http://i.imgur.com/pD6SMn6.jpg)
Title: Re: Cold Crashing Starter
Post by: JT on March 20, 2015, 06:54:31 PM
This answer, like many others, depends on who you ask.  I had planned on dosing my next starter with oxygen, shaking and then crashing at high krausen.  Previously I've done 18-24 hours on a stir plate, with no oxygen injection.  What yeast are you using?
Title: Re: Cold Crashing Starter
Post by: gmac on March 20, 2015, 06:55:35 PM
I am sure I am wrong but I am happy with me results. I let mine ferment out and then cold crash. Decant the beer and pitch dregs. Now, if I forget to make a starter ahead or don't have time. Then I make a starter using wort and pitch the entire thing at high krausen but I am doing 15 gal batches so one litre of starter is of little concern to me.
That's what I do and it works for me.
Title: Re: Cold Crashing Starter
Post by: flbrewer on March 20, 2015, 06:58:57 PM
What yeast are you using?

WLP 001
Title: Re: Cold Crashing Starter
Post by: JT on March 20, 2015, 07:01:43 PM
The good news is it is hard to go wrong with that yeast for beers within normal gravity ranges.
Title: Re: Cold Crashing Starter
Post by: denny on March 20, 2015, 08:30:00 PM
I am sure I am wrong but I am happy with me results. I let mine ferment out and then cold crash. Decant the beer and pitch dregs.

Just what I do, too.
Title: Re: Cold Crashing Starter
Post by: brewinhard on March 20, 2015, 09:06:59 PM
I too prefer to let my starter ferment to completion before cold crashing (usually around 24 hrs is enough depending on starter size and yeast freshness).  All starters done on a stir plate.
Title: Re: Cold Crashing Starter
Post by: Stevie on March 20, 2015, 09:15:28 PM
Now, if I forget to make a starter ahead or don't have time. Then I make a starter using wort and pitch the entire thing at high krausen...
I have been reserving this in my toolbox for a while. Such a smart and easy trick.
Title: Re: Cold Crashing Starter
Post by: klickitat jim on March 20, 2015, 09:17:02 PM
Unless I'm pitching at high krausen I chill after the growth phase.
Title: Re: Cold Crashing Starter
Post by: bassetman on March 20, 2015, 09:52:45 PM
After the cold crash when is the best time to use the starter and how long could you delay in a pinch?
Title: Re: Cold Crashing Starter
Post by: rjharper on March 20, 2015, 11:27:55 PM
Now, if I forget to make a starter ahead or don't have time. Then I make a starter using wort and pitch the entire thing at high krausen...
I have been reserving this in my toolbox for a while. Such a smart and easy trick.

I've done this a few times. Quite frankly, it's tempting to make this my normal practice.
Title: Re: Cold Crashing Starter
Post by: gmac on March 21, 2015, 03:50:15 PM
After the cold crash when is the best time to use the starter and how long could you delay in a pinch?

If I plan to brew Friday then I crash Thursday night and pitch the next day. I have had pitches wait 3 or 4 days with no issue but if things change and I can't brew for a week or so then I pull a bit of boiling wort in a clean mason jar, cap and cool and then put it on the yeast cake and pitch the whole thing a couple hours later. But I have only had to do this a couple times. Mostly I think it just wakes the yeast up.
Title: Re: Cold Crashing Starter
Post by: flbrewer on March 21, 2015, 08:48:02 PM
OK, to beat a dead horse...I'd really like to brew tomorrow, but the starter is still chugging along. The krausen has fallen considerably but there is still active fermentation.

Would cold crashing tonight for 12 or so hours and decanting be "throwing away" some of the potential active yeast vs. waiting for fermentation to fully finish?

Title: Re: Cold Crashing Starter
Post by: gmac on March 21, 2015, 08:53:42 PM
I believe that if the krausen has fallen then the yeast are now just building up resources and not reproducing. I believe you will be just fine to crash it tonight and then brew with it tomorrow. I certainly would.
Title: Re: Cold Crashing Starter
Post by: S. cerevisiae on March 21, 2015, 09:09:46 PM
Unless we are talking about a huge starter, crashing isn't really necessary.  I almost never crash my starters.  I pitch the entire contents of the starter vessel.  However, then again, I do not use a yeast stress inducing stir plate.
Title: Cold Crashing Starter
Post by: flbrewer on March 21, 2015, 10:29:25 PM
Unless we are talking about a huge starter, crashing isn't really necessary.  I almost never crash my starters.  I pitch the entire contents of the starter vessel.  However, then again, I do not use a yeast stress inducing stir plate.

So you're suggesting I just pitch it all tomorrow even though it may not be done at that point? I thought the consensus was to only pitch it all when it was at the peak.
Title: Re: Cold Crashing Starter
Post by: Wort-H.O.G. on March 21, 2015, 10:43:23 PM
Unless we are talking about a huge starter, crashing isn't really necessary.  I almost never crash my starters.  I pitch the entire contents of the starter vessel.  However, then again, I do not use a yeast stress inducing stir plate.

So you're suggesting I just pitch it all tomorrow even though it may not be done at that point? I thought the consensus was to only pitch it all when it was at the peak.

quite likely it will be done. but then again, you could just throw it in fridge now and then pitch it tomorrow. this last thursday, i removed some slurry from y IPA and made a small 1L starter. it took off in about 2 hours and peaked at about 7 hours. i put it in fridge and took it out the next day and pitched about 400ml after partial decant. my new IPA took off in about 10 hrs and is going wicked strong. i've done this the last few batches and beer is as good as ever.
Title: Re: Cold Crashing Starter
Post by: S. cerevisiae on March 22, 2015, 04:01:29 PM
So you're suggesting I just pitch it all tomorrow even though it may not be done at that point? I thought the consensus was to only pitch it all when it was at the peak.

It does not matter if fermentation is complete or not, crashing and decanting is optional if one is not using a yeast stress inducing stir plate.  The only thing that not decanting will do is dilute your final gravity a bit; therefore, wait until after you pitch to take your hydrometer sample.
Title: Re: Cold Crashing Starter
Post by: narcout on March 22, 2015, 05:48:58 PM
To me, crashing and decanting is about not wanting to dilute the beer.  However, I also don't particularly care for the flavor of unhopped DME that was been warm fermented, regardless of whether or not the starter has  been made with a stir plate.
Title: Re: Cold Crashing Starter
Post by: Philbrew on March 22, 2015, 09:39:31 PM
So you're suggesting I just pitch it all tomorrow even though it may not be done at that point? I thought the consensus was to only pitch it all when it was at the peak.

It does not matter if fermentation is complete or not, crashing and decanting is optional if one is not using a yeast stress inducing stir plate.  The only thing that not decanting will do is dilute your final gravity a bit; therefore, wait until after you pitch to take your hydrometer sample.
Except you will dilute your gravity a significant amount if you follow the size recommendations of the online yeast calculators.  I now believe that the online yeast calculators think that you will let the starter work to completion, crash and decant even if you're not using a stir plate.  I did a waaaaay too big shake-to-all-foam starter based on what MrMalty was saying that I needed for a shaken starter.  If you pitch a starter at or near high krausen those yeasties are in high gear.  You can make a much smaller starter than the calculators call for.  By pitching a 3-1/2 L starter in a 6 gal. (final vol.) lager, I didn't just reduce lagtime, I eliminated it altogether.  Unnecessary.
Title: Re: Cold Crashing Starter
Post by: S. cerevisiae on March 22, 2015, 10:07:31 PM
Except you will dilute your gravity a significant amount if you follow the size recommendations of the online yeast calculators.  I now believe that the online yeast calculators think that you will let the starter work to completion, crash and decant even if you're not using a stir plate.  I did a waaaaay too big shake-to-all-foam starter based on what MrMalty was saying that I needed for a shaken starter.  If you pitch a starter at or near high krausen those yeasties are in high gear.  You can make a much smaller starter than the calculators call for.  By pitching a 3-1/2 L starter in a 6 gal. (final vol.) lager, I didn't just reduce lagtime, I eliminated it altogether.  Unnecessary.

You are correct.  Pitching at high krausen allows one to reduce the required pitch rate by at least one half without a degradation in performance.  That's because one is pitching yeast cells that are still in the exponential phase.  Waiting until the culture has completed fermentation places the cells in a quiescent state where they have to reverse survival-related morphological changes that occurred at the end of fermentation before being able to go to work.  A culture that has reached quiescence also has low ergosterol and unsaturated fatty acid reserves.  These reserves have to be rebuilt when the culture is pitched, increasing dissolved O2 requirements.


 
Title: Re: Cold Crashing Starter
Post by: narcout on March 22, 2015, 10:13:30 PM
You can make a much smaller starter than the calculators call for.  By pitching a 3-1/2 L starter in a 6 gal. (final vol.) lager, I didn't just reduce lagtime, I eliminated it altogether.

Yes, but yeast growth in beer can have flavor consequences.

3.5 liters of starter wort in a 6 gallon (inclusive of starter) batch means roughly 15% of your volume is starter wort.  That seems undesirably high to me.
Title: Re: Cold Crashing Starter
Post by: Philbrew on March 22, 2015, 11:35:02 PM
You can make a much smaller starter than the calculators call for.  By pitching a 3-1/2 L starter in a 6 gal. (final vol.) lager, I didn't just reduce lagtime, I eliminated it altogether.

Yes, but yeast growth in beer can have flavor consequences.

3.5 liters of starter wort in a 6 gallon (inclusive of starter) batch means roughly 15% of your volume is starter wort.  That seems undesirably high to me.
Yes, that's part of my point.  The online yeast calculators lead a newbie like me to make a huge starter without saying that they expect that you will let it work out, crash and decant.  And you don't need to do all of that if you make a smaller starter, shake the bejeebers out of it and pitch at or near high krausen.  Saves time, effort, money.

So far, the beer tastes really good (unlagered and uncarbed).
A 3.5 L starter...undesirable, probably...unnecessary, definitely!
Title: Re: Cold Crashing Starter
Post by: S. cerevisiae on March 23, 2015, 12:38:45 AM
Yes, but yeast growth in beer can have flavor consequences.

The maximum cell density for 19 liters of wort is 3.8 trillion cells; hence, the difference between 100B cells and 200B cells is insignificant.  In fact, the difference between 100B cells and 400B cells is insignificant unless one is dealing with the cell destroying effects of high osmotic pressure. 

What's more important when pitching a starter is the health/state of the cells.  Cells that are pitched at high krausen are still in the exponential stage, which means that have ergosterol and unsaturated fatty acid reserves that only need to be topped off. Cells that have reached quiescence have undo the cell wall thickening that occurs at the end of fermentation.  They also have to rebuild the ergosterol and unsaturated fatty acid reserves that were wasted producing replacement cells after the exponential phase was exited.

log(3,800 / 400) / log(2) = 4 replication periods (rounded up)
og(3,800 / 200) / log(2) = 5  replication periods (rounded up)
log(3,800 / 100) / log(2) = 6  replication periods (rounded up)