Pitching dried yeast into cold wort

Buffers brewery · Nov 9, 2024

Earlier this year I changed my brewing process and now leave the partially cooled (sub 50C) wort in my garage overnight to finish cooling but also to let it settle out before syphoning off. Now the overnight outside temperature is dropping, by the following morning the wort temperature is well below pitching temperature. Today I’ve moved the fermenter with the cold wort into my brew fridge set at 20C and will pitch the yeast either tonight or tomorrow when it’s warmed up.

Am I overthinking this? Is there a temperature below which it’s not a good idea to pitch dried yeast?

YeastFace · Nov 9, 2024

I've read that it's better to pitch yeast into a colder temperature than you intend to ferment at. Not sure if that's wet or dry, but it's to avoid thermal shock or somesuch.

How cold are we talking? I take yeast out of the fridge for a few hours to get to pitching temperature. Your method just sounds like a more gentle example of that.

Yeast is pretty resilient, so reckon you'll be ok.

JockyBrewer · Nov 9, 2024

The yeast might stay dormant when too cold, but should start fermenting when it warms up.

The only real danger here is that the longer you leave the wort without getting your yeast going the danger of a wild yeast or bacterial infection taking hold increases.

Its6pmsomewhere · Nov 9, 2024

I don't see why there'd be an issue with that. We store the yeast in the fridge, I take mine out at the start of brewday and chuck it in when I have the wort down to pitch temp but realistically the yeast must still be colder so Im prob shocking it. The way you describe above is probably better for yeast as it's getting up to temp gently in a tasty environment?

Twostage · Nov 9, 2024

I take the packet(s) of yeast I'm going use out of the freezer and put it/them in my trouser pocket when its getting close to pitch time to warm them up.

I've read that pitching low can help prevent some off flavours forming, particularly for lagers. I've definitely pitched low before when I've wandered off and got distracted when chilling an ale wort and come back to 13 or 15c and just pitched anyway. No harm done.

An Ankoù · Nov 9, 2024

The dilemma for me is the rehydration temperature. When we rehydrate yeast in water we pitch around 30-35C for ale yeast and are warned not to use cold water. If I pitch directly, I tend to do so around 25+ C and let the beer cool naturally. I think everything said above is spot on except that nobody has considered the rehydration of the yeast cells.
So to answer the OP, I'd let the beer warm up first and I don't think you're overthinking it. Or rehydrate and let the sample cool to nearer the beer temp before pitching.

Its6pmsomewhere · Nov 9, 2024

Twostage said:
I take the packet(s) of yeast I'm going use out of the freezer and put it/them in my trouser pocket when its getting close to pitch time to warm them up.

Genius

. This is one of those 'how did I miss something so bloody obvious' moments

MashBag · Nov 9, 2024

Twostage said:
I take the packet(s) of yeast I'm going use out of the freezer and put it/them in my trouser pocket when its getting close to pitch time to warm them up.

I was going to say that!

For ale I would not pitch much below 18c

Twostage · Nov 9, 2024

When I make bread I take the yeast out of the fridge and put it straight into room temp water. Never given temperature equalisation a thought.

Buffers brewery · Nov 9, 2024

Thanks peeps for your feedback. The wort temperature this morning when I syphoned was 14.6C. I was in two minds and decided to warm it up a bit before pitching. My yeast is probably a bit above fridge temperature (4C) when I normally pitch into wort at about 23C so the larger bulk of warm wort quickly warms and rehydrates the yeast. Never had a problem so far. As @An Ankoù says, I was more concerned about the rehydration of the yeast thinking the yeast would come to life as it got warmer, a bit like priming a beer after cold crashing.

An Ankoù · Nov 9, 2024

Buffers brewery said:
I was more concerned about the rehydration of the yeast thinking the yeast would come to life as it got warmer, a bit like priming a beer after cold crashing.

I don't pretend to understand all the ramifications of rehydration, but I understand that, while the yeast is stable when dry and resilient when wet, it's quite vulnerable during the transition from dry to wet. Dormant yeast in suspension during and after a cold crash will wake up when the temperature rises, but I think that's quite different to what goes on during rehydration.
For what it;s worth.

Buffers brewery · Nov 9, 2024

The brew I’ve just done is a NEIPA and destined to have a shedload of hops added so the last thing I wanted was a complication with the yeast asad.

. I’ll be brewing a simpler pale ale next, when it might be colder, so I might just try and pitch into cold wort to see what happens ashock1

.
I’ll report back.

MrRook · Nov 9, 2024

Its6pmsomewhere said:
I don't see why there'd be an issue with that. We store the yeast in the fridge, I take mine out at the start of brewday and chuck it in when I have the wort down to pitch temp but realistically the yeast must still be colder so Im prob shocking it.

Dry yeast being colder than the wort is not much of an issue. You're more.likely to shock yeast when it's warmer than the wort.

MrRook · Nov 9, 2024

MrRook said:
Dry yeast being colder than the wort is not much of an issue. You're more.likely to shock yeast when it's warmer than the wort.

I routinely pitch dry yeast directly from the fridge with no issue.

Caramel Ox · Nov 10, 2024

Depending on your setup can’t you just put it in the brew fridge overnight set to 20 but with the fridge unplugged? Then it won’t drop lower.

Buffers brewery · Nov 10, 2024

Caramel Ox said:
Depending on your setup can’t you just put it in the brew fridge overnight set to 20 but with the fridge unplugged? Then it won’t drop lower.

Sadly, my boiler won’t fit in my brew fridge. Too tall.

Cwrw666 · Nov 10, 2024

Here's a thought - make your brew a little under volume then in the morning chuck in a kettle full of boiling water to bring it up to temperature and volume. Chuck in your yeast.

Buffers brewery · Nov 10, 2024

Cwrw666 said:
Here's a thought - make your brew a little under volume then in the morning chuck in a kettle full of boiling water to bring it up to temperature and volume. Chuck in your yeast.

That sounds like a really good solution. Ta athumb..

Lunesdale Brewer · Nov 10, 2024

I don't understand why you are keeping dried yeast in the fridge, it is stable at ambient temperature.
My practice with dried ale yeast (usually SO4) is to take an aliquot of wort approx 500ml at the end of boil, cool it and add the 11g packet of dried yeast to it to to start fermenting while the main batch is cooling. I then pitch it when there is visible sign of activity, typically about 1 -2 hours.
I recently pitched two 11g packets of Einstein lager yeast directly into a 23 litre batch at 10 deg C, it took about 48 hours before any sign of activity, the final beer was fine.

Agentgonzo · Nov 10, 2024

Lunesdale Brewer said:
I don't understand why you are keeping dried yeast in the fridge, it is stable at ambient temperature

It's more stable at cold temperatures.
If you take two sachets of dried yeast, keep one at room temperature and the next in the fridge, then when you pitch them both the one that was fridged will be healthier and have more viable cells than the one at room temperature.

If you only keep them for 6 months, you probably won't notice the difference. Keep them for 2 years, you probably will (they they'll both still work)

Pitching dried yeast into cold wort

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