Author Topic: Attenuation and Infection  (Read 4489 times)

Offline patrickswayze

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Re: Attenuation and Infection
« Reply #15 on: June 27, 2012, 10:48:56 AM »
I disagree on infection causing the low FG.

Even the *accidental* strains of brett take quite awhile to achieve super-attenuation (fermentation of normally unfermentable sugars). How long does it take to get to your FG?

155F isn't THAT high of a mash temp. If you aren't using any crystal malts, I wouldn't be surprised to see a FG in the 1.008-1.009 range. This is especially true if your mash temp falls a few degrees during the mash, it takes awhile for you to lauter, or if your mash thermometer is off.

I would check out the thermometer first. Then, think about mashing a bit higher. To get in the 1.015 range for my English Pale, I mash at 158-162 (depending on target starting gravity, amount of crystal, etc.).

My recipe is as follows for a 5.5 gal batch after boil

OG:1.054
FG:1.007
Maris Otter 10lbs 10oz
Victory 1lb 10oz
C10L 1lb
Cali Yeast pitch at 70deg. Fermentation started in less than 12 hours. Fermented between 70-72'F. Hit 1.017 (tasted amazing) in 4 days and hit 1.007 (tasted estery and too dry with no malt flavor) in 6 days.
My previous batches fermented down to about the same, but by big issue is that the bottles foam over. Not aggressively but slowly. They only foam if i open them warm, but if i serve them cold there is no foaming. I bottle at about two weeks usually but always take a 3 day gravity reading to see if the gravity fluctuates.

Offline Joe Sr.

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Re: Attenuation and Infection
« Reply #16 on: June 27, 2012, 12:08:42 PM »
They only foam if i open them warm, but if i serve them cold there is no foaming. I bottle at about two weeks usually but always take a 3 day gravity reading to see if the gravity fluctuates.

You probably know this, but the beer will hold more CO2 at colder temps which is why they only foam when you open them warm and not cold.

Sounds to me like you're over-priming and thus over-carbonating.  How do you measure your priming sugar?  By weight?  Or by volume (ie. 1/4 cup)?
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Offline patrickswayze

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Re: Attenuation and Infection
« Reply #17 on: June 27, 2012, 12:20:21 PM »
Im pretty sure i didnt over carb. at bottling i had 5 gal of beer. I always way out my priming sugar. I only used 2.9oz of priming sugar for this pale ale at 74'F bottling time.

Online morticaixavier

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Re: Attenuation and Infection
« Reply #18 on: June 27, 2012, 12:23:00 PM »
Have you ever taken a foamy bottle and de-gassed it and taken a gravity reading on that? just curious to see if the gravity has dropped any more.
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Offline patrickswayze

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Re: Attenuation and Infection
« Reply #19 on: June 27, 2012, 12:37:03 PM »
Have you ever taken a foamy bottle and de-gassed it and taken a gravity reading on that? just curious to see if the gravity has dropped any more.

Yeah i actually did that on the first two and they had droped about one point. But one of the newer batches read the same as when i bottled.

Online morticaixavier

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Re: Attenuation and Infection
« Reply #20 on: June 27, 2012, 01:00:45 PM »
Well, I am stumped, if the gravity is not dropping in the bottle than I don't think it's a brett infection. I don't know enough about microbiology to say if other spoilage organisms metabolize in such as way as to not affect the gravity.
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Offline patrickswayze

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Re: Attenuation and Infection
« Reply #21 on: June 27, 2012, 01:40:48 PM »
Would a point drop or more in the bottle cause it to foam over or constitute an infection?

Online morticaixavier

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Re: Attenuation and Infection
« Reply #22 on: June 27, 2012, 02:32:35 PM »
seems unlikely with only 2.9 oz sugar to start with, however 1.001 is what you would get adding about 1.6 oz sugar to 5 gallons so it is effectivly increasing the priming sugar effect by ~50%. I mean it seems odd that given that low a FG that it could drop any further without some bad a$$ yeast helping out but I really don't know.
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Offline nateo

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Re: Attenuation and Infection
« Reply #23 on: June 27, 2012, 03:29:32 PM »
Infections can be strange. I think there's something going on with your beers besides just overcarbonation. I've gone to 5 volumes without gushers. CO2 comes out of solution much more quickly if it has nucleation sites. If the 5vol beer is well-settled it won't foam over, if the yeast is up in solution, it foams over quickly. So I guess it's possible your infection isn't actually changing the gravity or carbonation level, but the bugs can stay in suspension, creating nucleation sites and foaming over. Just a WAG.
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