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10 day lager ferment?


Aeroboy86

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Hi everyone,

I am in the process of Brewing my first lager and following a lagering process.

I pitched 2 packets of mangrove jacks Bavarian lager yeast (rehydrated as per instructions) in a 22lt batch and has been fermenting at a constant 10degC. I have started taking gravity readings yesterday day 9 and I have got down to under a 1010 reading. I was expecting to wait a bit longer in the FV before I hit this gravity (Was expecting up to 20days). I am wondering of this is ok now to raise up to 17/18 degrees for a diacytal rest for a few days before lagering. Or should a wait till at least 2 weeks before the rest? Any suggestions would be great.

 

Cheers in advance.

James

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Do the SG again and make sure you're at FG before raising the temp. And it wouldn't hurt to give it a couple more days to let yeast do its' thing properly - not sure about lagering but the advice to give yeast time to clean up hasn't been specified for only ales so I guess it applies to lager as well.

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It should have ideally been raised earlier if doing a diacetyl rest in the fermenter. Usually when it reaches the low 1.020s, which would be after around 6 days. You want to raise it while the yeast are still active. If you are bottling though, it can be done in the bottles by keeping them at 18 or above for the 2-3 weeks it takes to carbonate, then lager them. If kegging, just throw in some sugar to get the yeast active again, and same procedure as bottles. 

I honestly don't know where this ridiculous idea came from that lagers take 3 weeks to reach FG. It's flat out rubbish. Maybe it's just from guys underpitching them, which can cause fermentation to be sluggish, but if you pitch a decent amount of yeast it will not take anything like that long, exactly as you've seen. Maybe it's because the yeast will mop up diacetyl if left at ferment temp, but it will take longer.

As for what the FG actually is, just do the usual two stable readings over 48 hours. It doesn't have to get below a certain number to be at FG. 

All my lagers are generally at FG in 10 days or less. It's not as unheard of as people think.

Edited by Otto Von Blotto
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+1 to what Otto man said. It would be very close to FG if not already there @ 1.010. You may have missed the boat to diacetyl rest as part of the primary ferment.

If you plan to still keg the beer you will have to naturally carbonate it at or above 18°C to some level using sugar/dextrose/malt extract to get the yeast fermenting again so it mops up the diacetyl. If you go ahead & force carb this as normal you will most likely end up with a sickly sweet beer that is almost undrinkable.

How do i know this? Because I made this mistake once. ONCE!

I learned a valuable lesson & haven't made that mistake again.

Cheers & best of luck sorting it out.

Lusty.

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+1 to all those in the know and raise the temp.  It does not have to be at FG to raise it. The idea is that it finishes the last points of ferment at the higher temp and ferments the diacetyl out.   It also  decreases the time it is in the fementer.  When you finally have FG leave for a day or 2 longer  then cold crash it. I go to 2O but many try to get as close to zero as possible. Leave it at CC temp for at least 3 days. Some do a week.  Then you can bottle/keg. If bottling prime with sugar and then let it rise to ambient for at least 2 weeks so the secondary fement can be down.  After that store for 3 months in the coldest darkest place you can find.  If kegging just keg it and store in the fridge for a couple of months.   

39 minutes ago, Journeyman said:

Do the SG again and make sure you're at FG before raising the temp.

Lager D rests are done before FG usually when the SG reaches about 1020ish then up the temp to about 18ish and let the final points of ferment happen at higher temp to remove the diacytal. 

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Raising the temp won't do a thing if FG has already been reached as the yeast are for the most part inactive. If FG has already been reached & diacetyl is still present you need to get the yeast to engage in a ferment again above 18°C to mop up the diacetyl while they are active. The only way to do this is to feed the yeast a sugar source again.

Don't even worry about the process of cold conditioning the beer until the excessive levels of diacetyl have been removed.

Cheers,

Lusty.

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Thank you everyone for the feedback. As mentioned this is my first attempt so lots to learn. I was expecting longer to hit the FG purely based on the reading I have done. Mangrove Jacks yeast suggests 2 packets when fermenting below I think 12 which is what I followed, they also suggested the 3 week ferment. 

I plan to bottle the brew so with this in mind, will the fermentation to prime assist in the diacetyl? Then after it is carbonated I can lager it for 5+ weeks? I have tasted it and it doesnt have an overly sweet taste at all, only a slight buttery taste which I assume is the diaceytl.

 

Thanks again 

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2 minutes ago, MartyG1525230263 said:

5 weeks is when I would start tasting but best after 10-12 weeks and 100%  the buttery flavour is the diaceytl.  The secondary will not get rid of the diaceytl now you will need time. 

So even though I am carbonating in bottle with priming sugar above 18degC you dont think this level of fermentation will do anything for the diaceytl? I was planning on lagering after the carbonation (obviously this is needed :))

 

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This is what I do and it works every time. 

Pitch and ferment at 10 or 12 or whatever it is. 

Allow the brew to rise to 18 when the SG drops to the low 1.020s, which is usually at 6 days in. Leave it up there until a few days after FG is reached, which is usually 14 days in. 

Then slowly ramp it down to 3 degrees over a few days, and leave for 1.5-2 weeks. At this point, keg it* and continue lagering in the keg. The reason for the slow ramp down and slightly warmer temperature is because the yeast are still working and this kicks them into cleanup mode. 

*If bottling, skip this part. Bottle after 14 days, allow to carbonate and then cool it down to lager for however long you choose. 

 

 

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24 minutes ago, Aeroboy86 said:

I plan to bottle the brew so with this in mind, will the fermentation to prime assist in the diacetyl?

Yes. Store the beer at or above 18°C & the secondary ferment to carbonate the beer will also mop up the excessive level of diacetyl.

Give it a few weeks in the bottle & if you wish to cold condition the beer after that then that is fine.

Cheers,

Lusty.

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9 minutes ago, Beerlust said:

I am a bit confused, doesn't that support my statement  "The secondary will not get rid of the diaceytl now you will need time"  such as lagering.  Or am I missing something? As secondary was not mentioned at all in that.  

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Hi Marty.

3 minutes ago, MartyG1525230263 said:

I am a bit confused, doesn't that support my statement  "The secondary will not get rid of the diaceytl now you will need time"  such as lagering.  Or am I missing something? As secondary was not mentioned at all in that.  

Politely, you are missing something. Diacetyl is dealt with as part of a fermentation. The buttery sweet overtones of diacetyl cannot be dissipated through bottle ageing or cold conditioning post a ferment (primary &/or secondary).

With true lager yeast fermentations the malt forward characteristics of the strain(s) are created in the beer to an extreme if allowed to ferment low under that 18°C mark throughout the primary ferment & allowed to reach final gravity. It requires a point during EITHER primary OR secondary fermentation for the yeast to dissipate excessive levels of this highly malt sweet character from the beer to acceptable drinking levels that only happens while the yeast are active & the wort/beer temperature is at or above 18°C.

You're a clever bloke so I can have you understand why most ale yeast fermented brews don't suffer from diacetyl related problems or require a rest. They are usually fermented at or above 18°C. 😉

If you wish to challenge that known ideal with fermenting lager yeast beers, do so at your own peril.

Cheers,

Lusty.

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Thanks, @Beerlust,  I have to admit that I tend to browse most of what I read these days for keywords. Thanks for the info much appreciated.  Good to know that if you bottle and miss the D rest it is no big deal. But if you keg and miss the D rest probably best to do a secondary in the keg.  Thanks, much appreciated.  This is the great thing about this hobby always learning.   Cheers, and yes the ale stuff is a given with the higher ferment temp.   

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3 hours ago, Otto Von Blotto said:

I honestly don't know where this ridiculous idea came from that lagers take 3 weeks to reach FG. It's flat out rubbish. Maybe it's just from guys underpitching them, which can cause fermentation to be sluggish, but if you pitch a decent amount of yeast it will not take anything like that long, exactly as you've seen.

If you pitch what they advise at the lower end of the ferment temp they suggest then it will take all of 3 weeks maybe more. Its just not enough at that temperature. My 19L batches with a 3L starter are usually 9-10 days at 10c with a ramp to 17 or 18 to hit FG. When i pitch a whole slurry or dump onto the cake it can be as low as 7 or 8.

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2 minutes ago, Greeny1525229549 said:

If you pitch what they advise at the lower end of the ferment temp they suggest then it will take all of 3 weeks maybe more. Its just not enough at that temperature. My 19L batches with a 3L starter are usually 9-10 days at 10c with a ramp to 17 or 18 to hit FG. When i pitch a whole slurry or dump onto the cake it can be as low as 7 or 8.

I am getting SG readings 9/10 days in (temp corrected) of around 1007, that is at 10degs constant for the entire time in FV (obviously coming down from original pitch temp) so that is well below the 3 weeks i was expecting at thia stage

 

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1 minute ago, Aeroboy86 said:

I am getting SG readings 9/10 days in (temp corrected) of around 1007, that is at 10degs constant for the entire time in FV (obviously coming down from original pitch temp) so that is well below the 3 weeks i was expecting at thia stage

 

Yeah you pitched high and brought it down low. That will lead to more yeast growth and a quicker ferment time. If you pitched at 10c and held it i suspect it would have been a lot longer. You would have needed 3 packets rather than 2 to get the same result.

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