Variable Brewing Temps - Good Or Bad?

[BOG]

Hi,

Does anyone know what the results are if the fermentation is stop start?

I have a brew belt but don't like leaving it on for long periods (as it cooks the beer) and definately not at night.

Problem is the temp drops so low at night that fermentation stops (no airlock activity). (<18 deg)
I'm doing an APA with fussy yeast. When I get up in the morning I turn on the brewing belt for about an hour and up the temp goes and she's off again bubbling away.

I don't leave it on for too long or the temp will go so high as 32 deg and kill the brew. (10 litre batch)

What's the general consenses on having the fermentation stop at night and restart in the day. Does it impart bad flavours or do bad things to the beer other than extend the fermentation period?


BOG

 

[Darren]

BOG,

In winter use a lager yeast. No need to heat at all.

search the forum for wyeast 2112. Probably the best yeast of choice for Sydney winter weather.

cheers

Darren

PS: Think about adding a bit of mashed grain to your beers. Not that hard and worth it for flavour

 

[Enerjex]

gday BOG, i've just got back into it and by no means an expert, but i have a brew going out in garage kicking along at a steady 13 degrees with saflager W-34/70 yeast and it couldnt be happier. i know where your coming from with teh up and down temps, i've got a brew fermenting inside the house as well with ale yeast and a heater pad. trying to keep it around 20 degrees but got down to 16 overnight last night when i left the pad off, but will overheat if the pad is left on too long.

 

[matti]

Ale yeast are usually more adaptable to temperature changes.
Ales also disguise off flavour better because of the complexity in the flavour.
In saying that, it is not advisable to allow the yeast to too much temperature difference as it may cause some off flavour by dying yeast in the mix.

It also depends on what type of yeast you have and I am no expert on which yeasts are more tolerant to temperature changes.

I have brewed ales where the temperature changes on the ferment has been 16-20 degrees in my garage.
The airlock have at time stopped when the seal is not tighten correctly and that used to worry me alot in the beginning.
That had no real ill effect as fermentation only slowed down a tad, only to kick off again when it reached 18 degrees.

The final beer has turned out very drinkable despite this.

But as a rule for the future it is advisable to control the temperature at the lower end for the chosen yeast strain at the beginning of fermentation for a cleaner finnish.

The reason for this is that the fruity flavour from ester and fusel are produce at a higher rate at the beginning of fermentaion.

These day i try to keep my ales yeasts between 16-18 degrees and leave a little bit longer 8-9 days before I rack it to a secondary for 2 days at same temperature.
I've got the luxury of having a brew fridge in the garage so i cold condition my ales for a week with finings to clear the beer.

Sorry about the rant but you should be ok as long as the temp does not go above 20.

 

[frogman]

Hi,

Does anyone know what the results are if the fermentation is stop start?

I have a brew belt but don't like leaving it on for long periods (as it cooks the beer) and definately not at night.

Problem is the temp drops so low at night that fermentation stops (no airlock activity). (<18 deg)
I'm doing an APA with fussy yeast. When I get up in the morning I turn on the brewing belt for about an hour and up the temp goes and she's off again bubbling away.

I don't leave it on for too long or the temp will go so high as 32 deg and kill the brew. (10 litre batch)

What's the general consenses on having the fermentation stop at night and restart in the day. Does it impart bad flavours or do bad things to the beer other than extend the fermentation period?
BOG

Why not try a timer on the heat belt?

 

[Enerjex]

the timer is a good idea, i was thinking about that only hours ago. a power point timer set to turn it on one hour off the next would help a lot. another thing to check is make sure you have a good seal in your fermenter as the tiniest air leak can cause your airlock not to bubble and where it may when the temps up a bit, when the temp drops the fermentation will slow down and may only produce enough pressure to go through the air leak not the airlock. when you put your lid on run a finger strip of vaseline around the lid seal and change your airlock grommets every 2-3 brews and this may show a difference as your brew may not be stopping afterall.

 

[Barge]

another thing to consider is that yeast creates carbon dioxide which dissolves in the beer. When the beer can't dissolve anymore CO2 it is saturated with CO2 and the excess CO2 produced will bubble out the airlock.

The colder a liquid is the more gas will dissolve in it. When you put the heat belt on in the morning, there's at least three things that are happening;

1. The yeast are spurred on to ferment faster and create more CO2

2. The CO2 that is dissolved in the beer becomes less soluble as the beer warms up, causing the airlock to bubble more rapidly

3. A little of both

As far as stop/start fermentations affecting your beer...I dunno.

Not very helpful but, FWIW I wouldn't stress to much, the fermentation may take a little longer but, without a fridge and thermostat there's not a lot you can do to control the temp down to a few degrees. Try wrapping the fermenter in a blanket or jumper. The timers a great idea too.

Good luck

 

[FazerPete]

the timer is a good idea, i was thinking about that only hours ago. a power point timer set to turn it on one hour off the next would help a lot. another thing to check is make sure you have a good seal in your fermenter as the tiniest air leak can cause your airlock not to bubble and where it may when the temps up a bit, when the temp drops the fermentation will slow down and may only produce enough pressure to go through the air leak not the airlock. when you put your lid on run a finger strip of vaseline around the lid seal and change your airlock grommets every 2-3 brews and this may show a difference as your brew may not be stopping afterall.

Just to clarify something, the brew is not going to get infected or oxidised just because the airlock is not actively bubbling. CO2 is heavier than air so it forms a blanket on top of the wort so the only way air can get in is if the pressure is greater outside of the fermenter than in it. As you are not likely to be brewing in a hyperbaric chamber then this isn't going to happen. In other words your beer isn't going to spoil just because fermentation has slowed down or stopped.

I wouldn't panic too much about the temps dropping down to 16 or so as it will slow the fermentation but it's not likely to have anywhere near as much of an effect on taste as letting the temperature get too high. It just means that your fermentation will take longer.

 

[jkeysers]

I 2nd that. My brews temps change all the time as I dont have a Fridgemate. I just make sure it doesn't go too far above the temp range. If it dips below, all it does is slow fermentation down from my experience. No biggy.

 

[BOG]

Everyone thanks for the response,

The yeast I was using for the Norwest Pale Ale (Fresh wort kit) was a Wyeast NorthWest 38?? (forgot) , the smack pack.

I found that below 21deg it shuts down fermentation completely (no bubble), raise the temp by as little as 2 degrees and up she starts again. I would leave it for a few hours , it cooled down and shut down. Warm it up and shes off again. It did this for days. I left it in the fermenter for 10 days and still wasn't able to get it to fully ferment out the sugars. (harvested yeast turned into brown bottle volcanos)

I've subsequently purchased the brewing belt and it works ok so long as the temps don't get too high. (See comment of origional post). Yes I'll give the timer a go and see what happens.

I've got a Cho Mog Porter going at the moment with 34/70 and it's fine going along at about 18deg.

My concern was if there where any off flavours produced by the stop start. You all seem to think no which is great.

So, in theory I could put a brew (with Northwest yeast) halfway through fermentation into the fridge and shut it down for a few days and then bring it out later when I'm ready to let it finish off. Interesting concept.


BOG

 

[Stuster]

I've got a Cho Mog Porter going at the moment with 34/70 and it's fine going along at about 18deg.

That's too high for that yeast. 10-14C would be more like it if you want a clean tasting beer.

 

[FazerPete]

Everyone thanks for the response,

The yeast I was using for the Norwest Pale Ale (Fresh wort kit) was a Wyeast NorthWest 38?? (forgot) , the smack pack.

I found that below 21deg it shuts down fermentation completely (no bubble), raise the temp by as little as 2 degrees and up she starts again. I would leave it for a few hours , it cooled down and shut down. Warm it up and shes off again. It did this for days. I left it in the fermenter for 10 days and still wasn't able to get it to fully ferment out the sugars. (harvested yeast turned into brown bottle volcanos)

I've subsequently purchased the brewing belt and it works ok so long as the temps don't get too high. (See comment of origional post). Yes I'll give the timer a go and see what happens.

I've got a Cho Mog Porter going at the moment with 34/70 and it's fine going along at about 18deg.

My concern was if there where any off flavours produced by the stop start. You all seem to think no which is great.

So, in theory I could put a brew (with Northwest yeast) halfway through fermentation into the fridge and shut it down for a few days and then bring it out later when I'm ready to let it finish off. Interesting concept.
BOG

Ignore the airlock completely as it isn't a sign of correct fermentation rate. 20c is a good temp to aim for with ales yeasts so putting it up to 23 won't be bad but it's better a few degrees lower. Instead of looking at the airlock, look at the krausen and see what's happening on top of the wort. I use gladwrap instead of lids and airlocks for this very reason. It stops me obsessing about the airlock and it lets me look at what's happening to my brew.

Your theory of putting in the fridge may not hold true because going down that low will cause all of the yeast to settle out of suspension if you left it for a few days or more. This means that it would probably not fire up again when re-warmed unless you stirred it up again.

 

[BenH]

The yeast I was using for the Norwest Pale Ale (Fresh wort kit) was a Wyeast NorthWest 38?? (forgot) , the smack pack.

I think you're referring to Wyeast 1332 (NorthWest Ale). I've fermented this successfully at 18 degrees before, and it's attenuated well but I had stable temps (brew fridge).

I may be biased (because I have a ferm fridge) but IMO temperature fluctuations should be kept to a minimum. Plenty of info about indicates that yeast can be stressed by temperature movements of just a couple of degrees over a 24 hour period.