[Philbrew]

 Common homebrew practice is to cool wort to 2 F below fermentation temperature (say, 60 for ales and 48 for lagers) and also cool yeast starters and re-hydrated dry yeast to close to those temps and then pitch the yeast into the fermenter.

I’ve rigged up an ice bath secondary coolant flow system for my immersion chiller.  I can now bring the wort down to 72-74 F with my ground water.  Then I put the outflow hose from the IC in the ice bath bucket, switch the valves on a garden hose Y and plug in the submersible pump in the ice bath.  This will bring 6.5 gallons of wort down to 60 F in about 5 minutes and down to 48 F in about 20 minutes.

Only problem is it takes far longer and some hassle to get the starter or re-hydrated yeast down to pitching temperature.  So I’ve started pitching the yeast in the boil kettle at 72-74 and bringing the (now) beer quickly down to fermentation temps.

The only (minor) downside that I can see is I lose a small amount of yeast in the trub at the bottom of the kettle after transfer.  Are there any other potential problems that I’m missing?  Cooling the yeast that fast…bad?
 

[klickitat jim]

I am not a fan of dropping yeast temps until they are done with fermentation. I'd avoid that. I only worry about chilling my lager starter wort before pitching the starter yeast. That way I'm not shocking the starter by dumping it into cold wort.

[erockrph]

I think if you get down to temp before the yeast comes out of its lag phase, then you can probably get away with it. I know I've done this out of necessity in the past with 34/70 (pitch in upper 50's, then put it in my ferm chamber set to 45F) and it didn't lead to any off flavors. But 34/70 is about the most forgiving yeast strain I can think of. I'd be hesitant to do this A) at temps that might throw fusels or B) with a flocculant yeast like Fullers.

[Iliff Ave]

Cooling in the summer is still the biggest challenge for me.

I pitch above fermentation temp all the time but try to keep it within the upper limits of the recommend temp range. I cool it down to the temp I want within 12 hours in the chest freezer.

I don't recommend it but it works for me 

[flars]

You could attemperate the yeast by adding cooled wort at intervals of a couple minutes apart.  Pitching the yeast when it is within 5°F of the wort temperature would not have a detrimental effect on the yeasts performance.

[802Chris]

I promise I'm not being a smart aleck..

Why exactly are you worried about this? I would say as long as the yeast is active from a starter or freshly rehydrated, you should just get your wort to temp and pitch it. The yeast will get to the temp of your wort very quickly based on sheer volume difference.

Maybe this is just another thing to stress you, that could worry less about?

[pete b]

I'm not getting why you don't just wait for the wort to cool. I usually pitch at night if brewing in the morning or the next morning if brewing at night. Just aerate first.

[Philbrew]

I promise I'm not being a smart aleck..

Why exactly are you worried about this? I would say as long as the yeast is active from a starter or freshly rehydrated, you should just get your wort to temp and pitch it. The yeast will get to the temp of your wort very quickly based on sheer volume difference.

Maybe this is just another thing to stress you, that could worry less about?

I've read that dumping yeast at 8-10 or so degrees higher than the wort can shock the yeast and cause it to make a form (petite-something, can't remember the term) that won't ferment properly.

[Philbrew]

I'm not getting why you don't just wait for the wort to cool. I usually pitch at night if brewing in the morning or the next morning if brewing at night. Just aerate first.

I had been doing it that way but this shortens my brew day.  And it should give the yeast a head start on any bugs.  Also, if I'm doing lodo (just started fooling with that), it may give the yeast a small head start before O2 is introduced.  I dunno.

[Philbrew]

I think if you get down to temp before the yeast comes out of its lag phase, then you can probably get away with it. I know I've done this out of necessity in the past with 34/70 (pitch in upper 50's, then put it in my ferm chamber set to 45F) and it didn't lead to any off flavors. But 34/70 is about the most forgiving yeast strain I can think of. I'd be hesitant to do this A) at temps that might throw fusels or B) with a flocculant yeast like Fullers.

I've done four batches this way so far.
- Pils with 34/70 in a starter.  No yeast related off flavors.  Minerally, but I suspect a water issue.  ??

- Best Bitters with Lallemand ESB (reported to be Fullers).  Took off like a rocket and finished in 2-1/2 days.

- Belgian Saison with Lallemand Belle Saison.  Fermented as expected (FG 1.002).  Delicious!

- Maibock with 2 packs of Fermentis s-189.  Took 1-1/2 days to get going but is currently chugging along.

[Phil_M]

I'm not getting why you don't just wait for the wort to cool. I usually pitch at night if brewing in the morning or the next morning if brewing at night. Just aerate first.

I had been doing it that way but this shortens my brew day.  And it should give the yeast a head start on any bugs.  Also, if I'm doing lodo (just started fooling with that), it may give the yeast a small head start before O2 is introduced.  I dunno.

Petite Mutant?

[Joe Sr.]

Why bother rehydrating dry yeast?  Sprinkle it on top and forget about it.

As far as a starter, if you're pitching at high krausen (shaken, not stirred) I don't think you need to worry about the temp, just pitch it.

It you're doing a stirred starter (or if you just don't want to pitch the starter wort) put it in the fridge to crash the yeast when you fire up your kettle.  Or the night before.

You may be over thinking this one.

[Philbrew]

Why bother rehydrating dry yeast?  Sprinkle it on top and forget about it.

As far as a starter, if you're pitching at high krausen (shaken, not stirred) I don't think you need to worry about the temp, just pitch it.

It you're doing a stirred starter (or if you just don't want to pitch the starter wort) put it in the fridge to crash the yeast when you fire up your kettle.  Or the night before.

You may be over thinking this one.

Yeah, I'm over thinking.  But with my feeble brain, that's an accomplishment.     This technique is just so out-of-normal that I wanted to get the forum thoughts on it.

I do SNS starters.  Never did buy a stir plate.

[Todd H.]

I've read that dumping yeast at 8-10 or so degrees higher than the wort can shock the yeast and cause it to make a form (petite-something, can't remember the term) that won't ferment properly.
[/quote]

Just to let you know, you don't have to worry about forming petite mutants just from a temperature shock (and I wouldn't call an 8F difference much of a shock to the cells... a temp shock to yeast is more like going from 30 to 37 or 42 degrees C, or 30C to 10C or 4C, those are much bigger jumps).
You need to damage DNA (generally mitochondrial DNA) to make petite mutants.  I've only done it using ethidium bromide; I'm sure there are other ways, just not a small temperature shift.

[ynotbrusum]

If it is any consolation, I have a brewing friend that has won many awards with a bock that he pitches in the low 60's, waits a day and then drops it into the mid 50's to complete the fermentation.  I think the yeast are very forgiving in the very early stage, as long as the wort at pitching is +/- 10 degrees F of where you are asking them to finish the work.  No science here, purely speculation and experience (my friend's experience - he is a pro brewer and went through the Seibel Institute coursework).

Me, I still pitch cool and bring it up a few degrees, when time allows for this approach, but I don't sweat it if I am in that 10 degree range, since it essentially mimics what my friend does.  YMMV and it could be somewhat yeast dependent - he favors 2206 for his bocks.