The Theory Of Lagering

[Marty1000000]

Hello all.

Wondering about the theory of lagering.
Which is the correct theory?

1. Rack and start lagering when the brew is about 2/3 done (SG around 1025?) so that during the lagering phase there are quite alot of fermentables for the yeast left to convert (all be it very slowly at about 4 degrees)

or

2. Allow the brew to ferment out almost completely (SG around 1008 depending on the ingredients) and then lagering so that the yeast has a chance to slowly "put the polish on" with the small amount thats left (esters & diacetyls etc) given that it won't be working very hard at 4 degrees.

My gut tells me that the second paragraph may be more correct because the yeast can only do so much down at 4 degrees....

You thoughts??
Cheers,
Marty.

 

[T.D.]

I must confess I rarely lager at all these days, but if I did, I would definitely let the beer get to (or very close to) terminal gravity. As much as there is some yeast activity at lager temps, it will be very low and you would run the risk of a stuck ferment if you lager it too soon.

 

[matti]

Rack @ 2/3 gravity 1.020-1.022
rest at 16-18 2-3 days.
Bring it down to 10-12 for a 5-7 days.
At two points above terminal gravity lager as cold as possible for 2-4 weeks.
raise the temp if bottling.
Or just filter keg and gas.
voila
matti

 

[SJW]

Rack @ 2/3 gravity 1.020-1.022
rest at 16-18 2-3 days.
Bring it down to 10-12 for a 5-7 days.
At two points above terminal gravity lager as cold as possible for 2-4 weeks.
raise the temp if bottling.
Or just filter keg and gas.
voila
matti

Not bad, but IMO I rack even closer to terminal gravity and then rack with a little dex. to fire up secondary fermentation. Warm up for a rest for a day or 2 until terminal gravity is reached then I CC for at least 2 weeks at -4 Deg C.

Steve

 

[matti]

:super:
That good if you pitch yeast at 10 degrees and no trace of diacetyls

If you pitch your yeast around 18-20 it is better to do rest @ 2/3.
This to give the yeast enough umph to finnish of the job and absorb the diacetyls.

well this is what the learnt one keep telling me.

 

[PostModern]

I'm no lager expert, having only made three of the things. Just now kegged a doppelbock which is not bad, considering I used NZ Hallertau.

I ferment at 10-12C for three weeks, then just turn off the freezer (or raise the thermostat to 20C) for 2-3 days, then just crank the temp down to minus 1 or 2C for about three weeks (if I can wait that long). 0C might be a better point for regular strength beer, but this guy started at 1.078, so it wouldn't freeze at well below 0. I then let it creep back up to 4 or 5C to transfer to the keg.

This one, I "Ross method" force-carbed about 30 mins ago and am currently sampling a 1/2 pint. Crystal clear and tasty. No diacetyl, just complex malty goodness with a hint of hops.

 

[danman]

got a pilsener going at the mo and was wondering what happens to the flavour if you do a diacetyl rest too early- eg 1024 or slightly higher? will this harm the yeasties or give fruity unwanted flavours or make no difference? ive ben fermenting at a constant 10 deg for a little over 7 days now-didnt start big.
cheers,dan

 

[T.D.]

Dan, I suppose the higher the SG when you start the diacetyl rest, the closer it is to fermenting the whole thing at (warmer) ambient temps rather than lager temps. I don't think you would "damage" the yeast at all but you may pick up some fruity flavours if you warm it up when the SG is fairly high. Exactly how high is too high is another matter. I am not a diacetyl rest kind of guy, as I pitch at lager temps so technically should never have a diacetyl problem, so I really can't offer much advice on that issue.

 

[danman]

i try to pitch at lager temps too-this one i pitched at 12C.
does the diacetyl only become an issue when yeast is pitched at higher temps eg 18-20C?
ive been doing diacetyl rest even tho i pitch below 15C
cheers,dan

 

[matti]

Pretty much. According to Zwickel and others lager brewers thats the trick.
There was a great thread earlier regarding lagers.
linky

 

[Zwickel]

gday mates,

about diacetyl rest has been said a lot already here on AHB, Id like to refer to the authors question only:

Hello all.

Wondering about the theory of lagering.
Which is the correct theory?

1. Rack and start lagering when the brew is about 2/3 done (SG around 1025?) so that during the lagering phase there are quite alot of fermentables for the yeast left to convert (all be it very slowly at about 4 degrees)

or

2. Allow the brew to ferment out almost completely (SG around 1008 depending on the ingredients) and then lagering so that the yeast has a chance to slowly "put the polish on" with the small amount thats left (esters & diacetyls etc) given that it won't be working very hard at 4 degrees.

My gut tells me that the second paragraph may be more correct because the yeast can only do so much down at 4 degrees....

Id say the paragraph 2 meets the point.

Let me shortly tell ya how Im gonna treat my Lager beers.

Pitching the yeast at ~10C, an amount of 1% of the batch size (minimum) very healthy and thick yeast.
Fermenting for 7 days, then start kegging.
At this time (after 7 days) the SG has dropped to around 1016-1018
Leave the batch for another 5 days at around 10C in the kegs, put a pressure relief valve at each keg with a pressure limit around 100kPa.
Then successive turn down the temp 2C per day until 0C is reached.
After 3-4 weeks at ~0C you may decide wether to filter the beer or just transfer it into another keg to lose the sludge.

Thats all.

edit: spelling

 

[hockadays]

got a pilsener going at the mo and was wondering what happens to the flavour if you do a diacetyl rest too early- eg 1024 or slightly higher? will this harm the yeasties or give fruity unwanted flavours or make no difference? ive ben fermenting at a constant 10 deg for a little over 7 days now-didnt start big.
cheers,dan

The book I use says to warm up for a rest at 16degc at 2/3 of the way through the fermentation which for most brews is at about 1.023. Thats when I normally do it and I have not noticed any fruity flavour in my lagers. The fruit flavours /esters as I am aware occur at the start of the fermentation from a high temperature and lack of airation of the wort.

Hockers

 

[Kingy]

my lagers are fermented at 10-12 degrees for 14 days then kegged and drunk :chug: :beer: it lagers in the keg and it gets nice and clear when about 5 schooners to go in the keg

 

[chris.taylor.98]

As far as I was aware the esters are all influenced by the temperature when the yeast is multiplying ( at the start of the fermentation cycle ) not a the end, so the diacytel rest should not create more esters. That is one of the considerations in the warm vs cold pitching issue.

The yeast produces the diacytel pre-cursor (acetolactic acid) which will convert to diacytel when oxidized (ie by the head space in a bottle etc ).

It seems there a many factors the contribute to diacytel production, and a lot of them lead back to underpitching and/or pitching unhealthy yeast ( see this article for some more info http://brewingtechniques.com/library/backi...sue1.2/fix.html ).

I recently heard a good podcast discussing diacytel ( latest one from CraftBrewer Radio http://radio.craftbrewer.org/shows/July3-07.mp3 )

They had a great tip for testing the presence of diacytel.

Just get a small jar, fill it with a bit of the fermenting beer and put the lid on. Pour some boiling water over it and let it set in the hot water for about 15 mins. Then chill it down to about 10C. This process should ensure the acetolactic acid converts to diacytel. Then open it up and smell the butterscotch goodness ... or not. Should be able to taste it too, if it is there.

 

[danman]

im plenty lazy when it comes to doing anything that doesnt need doing!
would you go to work if you didnt have to?
thought so
i like your idea kingy,may give it a go this time

cheers,dan

 

[The King of Spain]

I like the heading of your post, "the theory of lagering". Should probably be the "tradition of lagering". I know its not central to your post but in other parts of the world like the UK where the cold lagering period was not practical they developed other ways to clear a beer. Anyway thats my 2c.