Author Topic: lack of attenuation...here we go again...  (Read 1658 times)

Offline klickitat jim

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Re: lack of attenuation...here we go again...
« Reply #15 on: November 18, 2015, 10:24:16 PM »
Ph can do strange things sometimes. The calculators are great but sometimes the actual ph will vary unexpectedly. On my last brew day I calculated acid and salt additions for 5.5 mash and sparge, then a preboil of 5.0 ph. I gathered samples along the way. I did two brews with the same profile. After I was all done I did the lab work. Actual ph was 5.5 mash, 5.7 sparge, 5.0 preboil and 5.0 post boil with beer #1. Beer #2 was the same numbers as #1 except that the post boil ph actually went up to 5.1 ph. To me its odd that the calculations were right for the mash, off for the sparge, but then right again for preboil.

Back to your beer. 5.5 target and 152F seems in the ball park but that ph is kind of right on the line between top end for beta and sweet spot for alpha. 152 is getting to the top end of beta sweet spot and bottom end of alpha sweet spot. So a slight ph drift up would easily explain that 4-6 points extra FG. especially if it doesnt "taste" sweet. Dextrins reportedly dont taste as sweet as maltose. Sounds like yeast did its job, you just got a little more dextrinous wort than you expected.

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #16 on: November 18, 2015, 10:25:15 PM »
Thanks for all the tips. This one's got me stumped.
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Offline klickitat jim

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Re: lack of attenuation...here we go again...
« Reply #17 on: November 18, 2015, 10:27:06 PM »
Thanks for all the tips. This one's got me stumped.
Looks like I was typing while you were. I think I see what happened. Look back one post

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #18 on: November 18, 2015, 10:33:11 PM »
Ph can do strange things sometimes. The calculators are great but sometimes the actual ph will vary unexpectedly. On my last brew day I calculated acid and salt additions for 5.5 mash and sparge, then a preboil of 5.0 ph. I gathered samples along the way. I did two brews with the same profile. After I was all done I did the lab work. Actual ph was 5.5 mash, 5.7 sparge, 5.0 preboil and 5.0 post boil with beer #1. Beer #2 was the same numbers as #1 except that the post boil ph actually went up to 5.1 ph. To me its odd that the calculations were right for the mash, off for the sparge, but then right again for preboil.

Back to your beer. 5.5 target and 152F seems in the ball park but that ph is kind of right on the line between top end for beta and sweet spot for alpha. 152 is getting to the top end of beta sweet spot and bottom end of alpha sweet spot. So a slight ph drift up would easily explain that 4-6 points extra FG. especially if it doesnt "taste" sweet. Dextrins reportedly dont taste as sweet as maltose. Sounds like yeast did its job, you just got a little more dextrinous wort than you expected.

Thanks. I just have never experienced this. 60% apparent attenuation seems pretty severe for this situation but I get what you are saying. I went with 5.5 for a bit smoother of a character in a darker beer. I guess I didn't realize that pH could affect fermentability to such a degree but I am pretty clueless when it comes to water and chemistry. Before I started treating my water, my mash pH was normally 5.7-5.8 (according to bru'n water) with no noticeable effects on fermentation.
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Offline HoosierBrew

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Re: lack of attenuation...here we go again...
« Reply #19 on: November 18, 2015, 10:34:50 PM »
Also, stouts ( being higher in specialty malts, lower in base malt) can finish several points higher than a pale beer of equal OG - this beer isn't a stout but does have 15% grist from oats and carafa. I wouldn't expect it to finish 1.020, though. Chris - I assume you accounted for temp and the 'one degree high' in your hydrometer reading ?'
 
Jon H.

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #20 on: November 18, 2015, 10:45:10 PM »
Also, stouts ( being higher in specialty malts, lower in base malt) can finish several points higher than a pale beer of equal OG - this beer isn't a stout but does have 15% grist from oats and carafa. I wouldn't expect it to finish 1.020, though. Chris - I assume you accounted for temp and the 'one degree high' in your hydrometer reading ?'

I did account for the one point high...it actually read 1.021.

A lot of the yeast that I pitched is sitting on top but hasn't formed any type of krausen. I am going to wait 5-7 days before kegging. I will update if I see any activity. Maybe I will get lucky and get a few more points somehow.
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Offline klickitat jim

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Re: lack of attenuation...here we go again...
« Reply #21 on: November 18, 2015, 10:49:31 PM »
Ph can do strange things sometimes. The calculators are great but sometimes the actual ph will vary unexpectedly. On my last brew day I calculated acid and salt additions for 5.5 mash and sparge, then a preboil of 5.0 ph. I gathered samples along the way. I did two brews with the same profile. After I was all done I did the lab work. Actual ph was 5.5 mash, 5.7 sparge, 5.0 preboil and 5.0 post boil with beer #1. Beer #2 was the same numbers as #1 except that the post boil ph actually went up to 5.1 ph. To me its odd that the calculations were right for the mash, off for the sparge, but then right again for preboil.

Back to your beer. 5.5 target and 152F seems in the ball park but that ph is kind of right on the line between top end for beta and sweet spot for alpha. 152 is getting to the top end of beta sweet spot and bottom end of alpha sweet spot. So a slight ph drift up would easily explain that 4-6 points extra FG. especially if it doesnt "taste" sweet. Dextrins reportedly dont taste as sweet as maltose. Sounds like yeast did its job, you just got a little more dextrinous wort than you expected.

Thanks. I just have never experienced this. 60% apparent attenuation seems pretty severe for this situation but I get what you are saying. I went with 5.5 for a bit smoother of a character in a darker beer. I guess I didn't realize that pH could affect fermentability to such a degree but I am pretty clueless when it comes to water and chemistry. Before I started treating my water, my mash pH was normally 5.7-5.8 (according to bru'n water) with no noticeable effects on fermentation.
My post is just an educated guess. Obviously theres no way for me to just declare it so. The charting out of how alpha and beta react per temp and ph is good info, but also keep in mind that its just projected optimum ranges. Its not like when ph is 5.5 the beta is kicking butt, then at 5.51 it instantly denatures... But I think that when you are in those gaps, like top end for beta but sweet spot for alpha, that slight unexpected variation can happen. Couple that with some adjunct that didnt bring and DP to the party and I think you have a good suspect.

You mentioned 5.5 for flavor in the final beer. Try tweaking the final beer for that. I've been having great luck. See my thread on playing with final beer ph.
« Last Edit: November 18, 2015, 10:51:48 PM by klickitat jim »

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #22 on: November 19, 2015, 02:44:34 PM »
Took a look inside the fermenter this morning. There is a lot of floating yeast on top of the beer but no signs of activity. I am getting negative pressure in the airlock which is strange since I have been warming the beer up. Hopefully the yeast starts to drop out so I can keg. I can deal with 4% ABV beer for a change of pace...
« Last Edit: November 19, 2015, 02:47:19 PM by goschman »
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Offline brewinhard

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Re: lack of attenuation...here we go again...
« Reply #23 on: November 20, 2015, 06:48:34 PM »
I noticed that you did not mention any form of aeration prior to pitching or after pitching your yeast.  I highly doubt that your mash pH was that screwed up that it lead to such a poor fermentation.  Sometimes a lack of oxygen (especially with harvested yeast from a prior batch) introduced to the wort can lead to a stuck/stalled fermentation. 

Did you aerate this batch well?

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #24 on: November 21, 2015, 06:46:49 PM »
I noticed that you did not mention any form of aeration prior to pitching or after pitching your yeast.  I highly doubt that your mash pH was that screwed up that it lead to such a poor fermentation.  Sometimes a lack of oxygen (especially with harvested yeast from a prior batch) introduced to the wort can lead to a stuck/stalled fermentation. 

Did you aerate this batch well?

Good thought. I aerated this batch as normal although I don't do anything fancy like pure O2. Just a three foot drop when transferring into the fermenter from the spigot on my bottling bucket. Never had a problem before.

I took a reading this morning and it doesn't appear to have changed. I was going to keg but since I can't leave anything alone I added about 6 oz dark brown sugar dissolved in one cup of water. This should hopefully promote a bit more activity, possibly drop the FG a point or two, and get the beer closer to 4.5% ABV. 

Tasting the sample now. Kind of has a tangy sourness to it along with some tannic character like you would get from iced tea. Smells fine; malt, biscuit, touch of chocolate. Hopefully it is just from a lot of suspended yeast as this is a very low flocculator. At this point, it is what it is so I am not too worried though it would be a shame to have to dump it...we'll see...

« Last Edit: November 21, 2015, 06:53:24 PM by goschman »
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Offline brewinhard

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Re: lack of attenuation...here we go again...
« Reply #25 on: November 21, 2015, 06:52:22 PM »
Sometimes that is not enough oxygen for yeast.  Especially yeast that you harvested from a slurry from the last batch.  These yeast cells have pretty much used up all of their oxygen reserves and are in great need of O2 to build their abilities to properly reproduce and take in necessary materials for energy production. 

You may have gotten away with this in the past when using a fresher yeast pitch or dried yeast, but this practice may finally have caught up to you especially if you have some unfermentables in your grain bill. 

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #26 on: November 21, 2015, 06:56:01 PM »
Sometimes that is not enough oxygen for yeast.  Especially yeast that you harvested from a slurry from the last batch.  These yeast cells have pretty much used up all of their oxygen reserves and are in great need of O2 to build their abilities to properly reproduce and take in necessary materials for energy production. 

You may have gotten away with this in the past when using a fresher yeast pitch or dried yeast, but this practice may finally have caught up to you especially if you have some unfermentables in your grain bill.

Got ya. Thanks. I thought that a 3 day old slurry would be ready to go but I guess not. If one out of 50 batches has less than ideal oxygen that I guess I can deal with it. I am a yeast novice.  My results have been good for the most part so it is not worth it for me worry to about.
« Last Edit: November 21, 2015, 06:58:32 PM by goschman »
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Offline brewinhard

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Re: lack of attenuation...here we go again...
« Reply #27 on: November 21, 2015, 07:08:47 PM »
Aerating a beer is easy especially if you use carboys.   Once you rack it into your fermenter, simply cover the mouth with a sanitized piece of foil and swirl the crap out of it for 3-5 minutes based on OG.  The higher the OG the higher the minutes. 

Offline dilluh98

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Re: lack of attenuation...here we go again...
« Reply #28 on: November 23, 2015, 05:42:31 PM »
...or save your back and get a mix stir.  ;)

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #29 on: November 23, 2015, 05:47:17 PM »
My method of aeration works great for me with the exception of this batch which is still just a possibility...

Not sure when I will keg this guy now. Hopefully this weekend. Adding the sugar kick started the yeast and it currently has a thick krausen hanging around. I failed to realize that adding the sugar probably won't drop the FG but it will boost ABV.
On Tap/Bottled: Haze for Daze IPA, G Pils, Maibock, Kolsch, Summer Gold       

Fermenting: 
Up Next: Euro Pale, IPA