Frozen Kolsch - need to repitch when bottle conditioning?

[mhopperman]

I have a kolsch 'lagering' at what I thought was a fairly safe temperature setting to avoid freezing, but something has gone wrong. I have a probe in the centre of the wort, and I guess with the freezer, the bottom and tops are much colder than my 2 degrees C in the middle, so I've noticed a little layer on ice on top, but I would have to assume the bottle got frosty as well.

1) Will that amount of freezing, maybe for a day or so (I would give the fermenter a little bump to confirm no freezing and it had been fine prior at that temp), should I be on the safe size and repitch some yeast when it comes time to bottle condition? I've read a couple of grams of dry yeast would be fine?

2) Will repitching yeast basically undo the cold crashing/gelatine/lagering steps I've taken? Or will the small amount of yeast not really affect clarity much? I'm planning to use s-05 because it's what I have on hand.

3) In the future, is it best practice to control the ambient temp and not the fermenter temp for cold temps? I notice on Brulosophy they advise to move your probe to the freezer/fridge for cold crashing, but don't specify why.

Thanks

 

[madscientist451]

Its likely your existing yeast will be fine for bottle conditioning. If you have the time, you can run a few test bottles and see what happens.

 

[rburrelli]

Yeast are hardy creatures. I agree that there is probably no need to repitch.

 

[hottpeper13]

That happened to me with 2565 and a cold Wisconsin winter. The top had a thin layer of ice and was the clearest beer to date before packaging. I can't remember if it was bottled or kegged but it was a fantastic brew.

 

[odie]

man, I had a kolsch I was cold crashing...when I went to rack from the ferm bucket to the keg I only got half the beer out. WTF??? opened the bucket lid and it was an iceberg inside. took quite a while to get the frozen beer into the keg.

came out great though.

 

[mhopperman]

Its likely your existing yeast will be fine for bottle conditioning. If you have the time, you can run a few test bottles and see what happens.

Yeah, I might do a test bottle while it's in its lagering state and see if that does anything. Comforting to know it sounds like the yeast probably survived well enough for bottle conditioning.

 

[Miraculix]

man, I had a kolsch I was cold crashing...when I went to rack from the ferm bucket to the keg I only got half the beer out. WTF??? opened the bucket lid and it was an iceberg inside. took quite a while to get the frozen beer into the keg.

came out great though.

Should have left the ice inside... Eis Bock!

 

[odie]

Should have left the ice inside... Eis Bock!

that thought did occur to me at the time...big boost in ABVs...

 

[IslandLizard]

3) In the future, is it best practice to control the ambient temp and not the fermenter temp for cold temps? I notice on Brulosophy they advise to move your probe to the freezer/fridge for cold crashing, but don't specify why.

Mount the probe against the outside of fermentation vessel, about in the middle of the beer height. Put a piece of 1/4"-1/2" dense (packing) foam over it for partial insulation, and strap it down. Tape won't work, due to condensation. Similar to strapping a probe to the side of a keg in a keezer.

Now, there may be a slight difference between the temp you set on the controller and the actual temp of the beer inside the fermenter. So adjust accordingly.

 

[mhopperman]

Mount the probe against the outside of fermentation vessel, about in the middle of the beer height. Put a piece of 1/4"-1/2" dense (packing) foam over it for partial insulation, and strap it down. Tape won't work, due to condensation. Similar to strapping a probe to the side of a keg in a keezer.

Now, there may be a slight difference between the temp you set on the controller and the actual temp of the beer inside the fermenter. So adjust accordingly.

In my case I have a thermoprobe so the probe is right in the centre of the beer. I don't know what went wrong, but my controller will vary a degree (celsius) or two before adjusting. I figure the centre of the beer was warmer than the outside, due to it sitting directly on the freezer floor. Would you recommend taping it to the side as an alternative to the thermowell?

 

[MikeCo]

Adding bottling yeast may not be necessary, but doing so is a cheap and easy way to assure there is enough yeast to carbonate the bottles quickly. I don't think it will affect clarity; the yeast will settle out at the bottom of the bottles.

 

[IslandLizard]

In my case I have a thermoprobe so the probe is right in the centre of the beer. I don't know what went wrong, but my controller will vary a degree (celsius) or two before adjusting. I figure the centre of the beer was warmer than the outside, due to it sitting directly on the freezer floor.

Yup, that's probably what's happening. Is the probe inside a thermowell?

Now the freezing temp of your beer is a few degrees lower than 0°C too, due to alcohol and unfermentables content. So that increases the margin.

Have you checked/calibrated the probe/controller?

Below freezing temps by itself, or a little slush is not going to kill the yeast, but hard freezing (needle-like crystals being formed) could. That's why we "freeze" yeast slurries with some glycerol added, to prevent that.

 

[mhopperman]

Yup, that's probably what's happening. Is the probe inside a thermowell?

Now the freezing temp of your beer is a few degrees lower than 0°C too, due to alcohol and unfermentables content. So that increases the margin.

Have you checked/calibrated the probe/controller?

Below freezing temps by itself, or a little slush is not going to kill the yeast, but hard freezing (needle-like crystals being formed) could. That's why we "freeze" yeast slurries with some glycerol added, to prevent that.

Yep, I typically put the probe into a thermowell right in the centre of the beer.

I bottled today after setting the temp controller to around 2.5 degrees C for about three weeks, and kept the probe out of the fermenter altogether to see if that helped prevent any freezing, but as it turned out there was a huge amount of ice down the bottom. Pitched 3 grams of yeast, because while it may have survived the initial bit of ice, this was a total mess.

 

[IslandLizard]

kept the probe out of the fermenter altogether to see if that helped prevent any freezing [...] there was a huge amount of ice down the bottom.

Where did you put the probe, instead?

 

[Protos]

1C by the edges of the vessel and a bit of ice on the surface is a standard occurence with Lagers.
And the Lager yeasts are even slower and weaker fermenters than Koelsch-type ale strains. Nevertheless, in the huge majority of cases that doesn't prevent Lager yeasts to ensure a proper carbonization in bottled beers, when the beers are kept for carbonization at a higher temperature.
In your case, I won't worry and won't add any additional yeast at bottling.

 

[mhopperman]

Where did you put the probe, instead?

Just hanging into the freezer to get the ambient temp

 

[IslandLizard]

Just hanging into the freezer to get the ambient temp

Could you please reread my post in #9?

 

[mhopperman]

Could you please reread my post in #9?

You are saying strapping the probe to the outside of the fermentation vessel is more suitable than placing it in a thermowell at the centre of the vessel or measuring the ambient temp of the chamber?

 

[IslandLizard]

You are saying strapping the probe to the outside of the fermentation vessel is more suitable than placing it in a thermowell at the centre of the vessel or measuring the ambient temp of the chamber?

Yes!
With an approx. 2-3" square piece of 1/4" dense but flexible packaging foam over the probe.

The reasons being:
Doing so will read an average temp between the temp of the fermenter (and liquid it contains) and the "ambient" (inside ferm chamber) temps.
It also reduces the frequency your temp controller cycles your ferm chamber's compressor, compared to hanging the probe in thin air.

 

[IslandLizard]

With an approx. 2-3" square piece of 1/4" dense but flexible packaging foam over the probe.

Let me add, position the probe, heightwise, about midway between the bottom of the fermenter and (the top of) the beer level.

Many of us do the same with the probe in our kegerator/keezer, just strapped down a little lower, somewhere in the bottom 1/4 of the fullest keg, and also under a piece of foam.

 

[mhopperman]

Let me add, position the probe, heightwise, about midway between the bottom of the fermenter and (the top of) the beer level.

Many of us do the same with the probe in our kegerator/keezer, just strapped down a little lower, somewhere in the bottom 1/4 of the fullest keg, and also under a piece of foam.

Yeah, that makes sense. Will definitely give that a try next time.