Another temperature question

[rpt]

My beer is currently fermenting in my brew fridge at 20C. When it hits target SG and sticks for a few days I will leave it for another 3 days for the yeast to clean up. Then I shall transfer to a secondary to leave at 5C for a week or so until I get chance to bottle. Should I reduce the temperature of my primary FV to 5C before racking, or perhaps some other temperature like 10C for a day or two? As I can do it I wondered if there was any benefit to a particular temperature regime.

 

[Dr Mike]

I don't know if there is a right and wrong way to do it but, in the belief it's a good idea to leave as much yeast behind as possible in the primary, I drop the temperature a day or so before transferring. This also seems to make the yeast cake nice and firm so I can rack all the beer off without really disturbing it.

 

[pittsy]

if your transfering to a 2nd fv and then leaving it you should transfer before fermentation is complete so you have some c02 covering your brew , so fv for about 4 to 5 days then 2nd fv for 5 days more then drop temp :thumb:

 

[rpt]

if your transfering to a 2nd fv and then leaving it you should transfer before fermentation is complete so you have some c02 covering your brew , so fv for about 4 to 5 days then 2nd fv for 5 days more then drop temp :thumb:

That's a very good point. In the future I shall probably leave the beer in the primary FV and lower the temperature in the fridge before transferring to the bottling bucket. The trouble is, currently my primary FV is also my bottling bucket. As I want to batch prime, I need to transfer it somewhere in between. As it is currently fridge temperature in my garage I should be able to get away with this at the moment.

 

[rpt]

A change of plan. I'm getting a new bottling bucket so won't transfer out of the primary until I am ready to batch prime. Once fermentation and cleanup is over I can drop the temperature. But what is the best temperature? Is 5C the best or is 2C better? Cool it as quick as possible or lower it gradually over a few days?

 

[jonnymorris]

I doubt the rate of cooling is significant but rather that it'll clear better at a lower temp.

 

[orlando]

But what is the best temperature? Is 5C the best or is 2C better? Cool it as quick as possible or lower it gradually over a few days?

I had this discussion recently with someone who teaches micro brewers and he said you should come down slowly in steps, this gives the yeast maximum time to clear up and helps to settle it out. Sub 5 if possible is where you want to end up.

 

[rpt]

Any idea what sort of steps and how quickly? 2C sounds like a good target though.

 

[orlando]

Any idea what sort of steps and how quickly? 2C sounds like a good target though.

What seems to matter most is how big the step is, changes of just 2-3 degrees can affect the yeast so if you have time to, do it in small steps over 3 days. Here's a quote from the book Yeast by Chris White (White labs) and Jamil Zainasheff that might help "...very rapid reduction in temperature (less than 6 hours) at the end of fermentation can cause the yeast to excrete more ester compounds instead of retaining them". They also suggest avoiding this if you want to harvest the yeast for repitching because it expresses "heat" shock proteins. Lager is a different animal though, I don't brew lagers so someone else will have to help with that.

The main point remains that taking the beer off yeast too soon can leave it prone to faults like diacetyl, it is the main reason why using so called secondary fermentors is now largely avoided. The old days fear of autolysis (yeast dieing and producing off flavours) has been shown to be untrue on our time scales of just a few weeks.

Hope that helps.

 

[rpt]

It would take a week to go from 20C to 2C at 2 or 3 degrees a day. What do they mean by very rapid reduction in temperature (less than 6 hours)?

 

[orlando]

It would take a week to go from 20C to 2C at 2 or 3 degrees a day. What do they mean by very rapid reduction in temperature (less than 6 hours)?

To sub 5. If you adjust it in the morning before work then again at night etc that would be fine, every 8 hours would be OK but you gotta sleep :grin: Once you get below 14c with an ale yeast it's pretty much finished so you can cool rapidly from there.

 

[rpt]

Found this on the White Labs website:

To minimize the diacetyl attributes in beer, it’s recommended that the fermenting wort rest once the beer has reached terminal gravity for 48 hours at 62-70 degrees prior to crashing the temperature. This stage allows to yeast to reabsorb the diacetyl.

So that sounds like leave it for 2 days for the yeast to clean up and then drop the temperature as quick as possible. But I like your suggestion of cooling to 14C in a couple of days and then crashing.

 

[Good Ed]

there is another school of thought, practiced by the aforementioned Jamil Zainashelf that after initial primary fermentation is complete that you increase the temperature to say 22-24C to assist in the yeast cleaning up stage, because by then you would not get any of the bad side effects associated fermenting at high temperatures initially, you would then cool after a period of 4-5 days. I have done this with my last few brews.

However depending on the style you are brewing and your tastes, you may not want the yeast to clean up after itself, in which case you would cool when you have your FG and drop the yeast out.

There is no absolute way to do these things, just many ways. Of course when discussing temperatures you would need a fermenting fridge with control over heating and cooling to achieve these things.

 

[orlando]

there is another school of thought, practiced by the aforementioned Jamil Zainashelf that after initial primary fermentation is complete that you increase the temperature to say 22-24C to assist in the yeast cleaning up stage, because by then you would not get any of the bad side effects associated fermenting at high temperatures initially, you would then cool after a period of 4-5 days. I have done this with my last few brews.

However depending on the style you are brewing and your tastes, you may not want the yeast to clean up after itself, in which case you would cool when you have your FG and drop the yeast out.

There is no absolute way to do these things, just many ways. Of course when discussing temperatures you would need a fermenting fridge with control over heating and cooling to achieve these things.

Your quite right, a You Tube interview with Charlie Barmforth on the BrewSmith channel advocates this technique mid way through the fermentation but only by a couple of degrees. Paradoxically raising the temperature increases diacetyl production but increases the yeasts ability to reabsorb IF given enough time to do so. Al of this depends on the vigour and viability of the yeast i the first place but that's another thread. :thumb:

 

[Markus]

For my first brew, I just moved the primary FV from a 20C environment (where it had been for 10 days) to a 14C environment. I plan on letting it sit in there for another 3/4 days to clear a little and then rack to a keg. Does this sound like good practice?

 

[bunkerbrewer]

I think 20° down to 14° is what Fuller's do for a few days before dropping the temp further, so you're in good company :)

I think it would help - but note what others have said - you shouldn't let the fermentation temp drop (or raise) too quickly, and fluctuations are bad.