Cold Crash at 8ºC/46.5ºF?

[Darren Birkett]

I acquired an old refrigerator that I've converted to a fermentation fridge. It's old and slow to get to temp, but it's fine with fermentation temps (around 18ºC, or 64.4ºF).

If I try and use it to cold crash (testing with water in a ferm bucket), it takes 2-3 days and struggles to get below 7-8ºC (44.5-46.5º F), which as I understand it is warmer than most people cold crash at (generally under 5ºC/41ºF).

I should add that I do extract/specialty grain brews, and have thus far used exclusively US-05 which has always dropped pretty clear for me prior to obtaining the fridge. I haven't actually tried to cold crash an actual beer with this yet, and whilst one answer might be "well if it drops clear with out cold crashing, why bother?", I will say that I'm looking to move onto other yeasts and so an answer on this would be useful.

My question is, is there any real benefit to crashing at 8ºC, or should I just not bother? Will I get "some but not all" of the benefit? Is there any scientific data to show why people go close to 0ºC/32ºF ?

Thanks!

 

[VikeMan]

My question is, is there any real benefit to crashing at 8ºC, or should I just not bother?

I think any temperature decrease is useful, because it encourages yeast to flocculate. It also encourages polyphenols and proteins to get together and drop out.

When you crash, are you able to pressurize your fermenter to avoid sucking air/oxygen?

Also, if your fridge can't get below 8C, it might not be long for this world without some maintenance.

 

[Darren Birkett]

When you crash, are you able to pressurize your fermenter to avoid sucking air/oxygen?

No, it's a basic bucket fermenter. I'm not even using an airlock because it wouldn't fit in the fridge if I did - just a bit of aluminium foil over the hole to allow fermentation gases to escape.

Also, if your fridge can't get below 8C, it might not be long for this world without some maintenance.

I agree, but it cost me £1 on ebay so I can't really complain!

 

[VikeMan]

No, it's a basic bucket fermenter. I'm not even using an airlock because it wouldn't fit in the fridge if I did - just a bit of aluminium foil over the hole to allow fermentation gases to escape.

With an airlock, you could use a balloon to collect CO2 and to (later) supply it back into the fermenter as the pressure drops during crashing. I definitely would not recommend crashing without the ability to keep O2 out.

 

[Darren Birkett]

With an airlock, you could use a balloon to collect CO2 and to (later) supply it back into the fermenter as the pressure drops during crashing. I definitely would not recommend crashing without the ability to keep O2 out.

Wow, never thought of collecting CO2 to feed back later on - I could attach a balloon to the rubber gasket where the airlock would normally sit. Having said that, I bottle using a bottling bucket. On transfer to that bucket, and then into my bottles, my beer is entirely exposed to the air which I'd have thought was way more of an issue with oxidation than anything sucked in to the head space during a pressure drop from a cold crash? I don't really have a system to avoid this during bottling.

 

[VikeMan]

Wow, never thought of collecting CO2 to feed back later on - I could attach a balloon to the rubber gasket where the airlock would normally sit.

Do a forum search for "balloon".

On transfer to that bucket, and then into my bottles, my beer is entirely exposed to the air which I'd have thought was way more of an issue with oxidation than anything sucked in to the head space during a pressure drop from a cold crash? I don't really have a system to avoid this during bottling.

Unfortunately, it's not really a matter of which is worse, but more that O2 absorbed from each process is additive.

 

[wsmith1625]

You should also consider getting an external temperature controller to have better control of your fermentation temps. Attach the temperature probe to your fermenter so the fridge turns on and off relative to your beer temperature, instead of the ambient air temp. You'll definitely get a more consistent fermentation temps this way.

Also, if you want to cold crash, you would need to disable the internal thermostat on your fridge and you may actually get it colder than 8ºC . I had to do this on mine.

 

[Darren Birkett]

Unfortunately, it's not really a matter of which is worse, but more that O2 absorbed from each process is additive.

Point taken. I'll definitely look into using a balloon, thanks!

You should also consider getting an external temperature controller to have better control of your fermentation temps. Attach the temperature probe to your fermenter so the fridge turns on and off relative to your beer temperature, instead of the ambient air temp. You'll definitely get a more consistent fermentation temps this way.

Thanks yes, I have it hooked up to an STC-1000, so am able to ferment consistently. It's just the slightly higher temp for the cold crash I wasn't sure about.

Also, if you want to cold crash, you would need to disable the internal thermostat on your fridge and you may actually get it colder than 8ºC . I had to do this on mine.

I'd have expected a fridge to get below 8ºC without having to disable/bypass the internal thermostat (I think around 3-4ºC is generally the temp most fridges keep food at)? My observation also is that it is constantly running, desperately trying to cool further, rather than the compressor being turned on and off by the internal thermostat. I suspect maybe the coolant is low, or there is an issue with the heat cycle as it does build up frost at the back.

I'll give it a go at cold crashing at 8ºC (or whatever it manages) on my next brew and see what it manages to do.

 

[VikeMan]

I'd have expected a fridge to get below 8ºC without having to disable/bypass the internal thermostat

Yes, of course any normally operating fridge should be able to get well below 8C. 8C would not be very good at keeping food fresh.

My observation also is that it is constantly running, desperately trying to cool further, rather than the compressor being turned on and off by the internal thermostat.

Disabling the thermostat won't help you.

 

[Darren Birkett]

Do a forum search for "balloon".

Unfortunately, it's not really a matter of which is worse, but more that O2 absorbed from each process is additive.

I know it's slightly OT, but I've been thinking about this a bit more. Would I be better just skipping the bottling bucket step and bottling straight from the tap on my fermenter (it sits just above the trub line usually) - using a line and bottling wand. The main reasons I use the bottling bucket are to mix in the carbing sugar which I've dissolved in boiling water and cooled, and to leave most of the trub behind in the fermenter which makes bottling cleaner. However I suppose I could switch to using carbing drops in the bottles and skip this step, if oxidation is such a big issue (it's not something I've even thought about as I've been trying to improve my brews - initially I've focused on controlling ferm temps by getting this fridge setup).

 

[VikeMan]

I know it's slightly OT, but I've been thinking about this a bit more. Would I be better just skipping the bottling bucket step and bottling straight from the tap on my fermenter (it sits just above the trub line usually) - using a line and bottling wand. The main reasons I use the bottling bucket are to mix in the carbing sugar which I've dissolved in boiling water and cooled, and to leave most of the trub behind in the fermenter which makes bottling cleaner. However I suppose I could switch to using carbing drops in the bottles and skip this step, if oxidation is such a big issue (it's not something I've even thought about as I've been trying to improve my brews - initially I've focused on controlling ferm temps by getting this fridge setup).

Yes, you can certainly bottle from a fermenter if you have a reliable way to dose the bottles with sugar. Some people like carbonation drops. Some hate them. You can also use Domino Dots.

The main drawback (IMO) is if you want a CO2 level that would require non-whole numbers of drops/dots per bottle.

You can also add table sugar to each bottle, though you might find measuring each dose to be a PITA.

 

[Darren Birkett]

Yes, you can certainly bottle from a fermenter if you have a reliable way to dose the bottles with sugar. Some people like carbonation drops. Some hate them. You can also use Domino Dots.

The main drawback (IMO) is if you want a CO2 level that would require non-whole numbers of drops/dots per bottle.

You can also add table sugar to each bottle, though you might find measuring each dose to be a PITA.

yeah, I guess the decision is whether the extra faff outweighs the problems that [may] come with oxidation. I've certainly been getting off flavours in my beer that I want to eliminate, and I wonder if oxidation is one of the reasons (I'm not very good at identifying the 450 million billion or so off flavours that seem to have been documented, so find it difficult to identify what the cause is)

 

[VikeMan]

I've certainly been getting off flavours in my beer that I want to eliminate, and I wonder if oxidation is one of the reasons (I'm not very good at identifying the 450 million billion or so off flavours that seem to have been documented, so find it difficult to identify what the cause is)

Do you have a homebrew club in your area? I always say that the worst person to evaluate a beer is the brewer himself.

 

[Darren Birkett]

Do you have a homebrew club in your area? I always say that the worst person to evaluate a beer is the brewer himself.

I definitely agree with that principle! But sadly, at least last time I checked, I couldn't find one near me. I also asked on (what I think is) the UK sister forum to this forum, and nothing.

 

[homebeerbrewer]

I haven't read the entire thread, so this may have been mentioned, but if your fridge is struggling to get down to that temp, it's not going to last long. However, it would probably be fine for a while if you just keep it at ale fermentation temps.

My recommendation is to get a freezer and a temperature controller. A freezer would reach lower temperatures than a fridge can, allowing you to cold crash right at 0c of you want. Crashing at that temp isn't necessary though, since pretty much everything will have dropped out before it gets that low.

 

[Darren Birkett]

I haven't read the entire thread, so this may have been mentioned, but if your fridge is struggling to get down to that temp, it's not going to last long. However, it would probably be fine for a while if you just keep it at ale fermentation temps.

Yes indeed, it was already mentioned that my £1 ebay fridge is probably on its last legs! I'll see how long I can get out of it before replacing

As it goes, after the conversation in this thread, and doing more reading on the forum around oxidation and oxygen ingress when cold crashing, I'm thinking that for now I might not actually cold crash anyway. So that might extend the life of the fridge for a little longer.

 

[Mark3885]

Why not recharge your fridge cooling system? Look up piercing valves or go to YouTube, you’ll see many videos how to do it for less than $20 . I recharged my mini freezer 2 yrs ago , and it cools faster than my new freezer does, just a thought.