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Over Attenuation

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centralpabrewer

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I brewed a Bohemian Pilsner on 12/30. Did my first ever single decotion mash. My grain bill was 10lbs German Pils and 1lb carapils. Yeast was a 1.5L starter of Wyeast 2124 Bohemian Lager.

Brew day was good. Had a few issues hitting my mash temps, but not too bad, wound up at about 150. Original gravity into the fermenter was 1.058.

My issue is after 2 weeks in the primary at 55F, my gravity is now at 1.004. At least that is what my refractometer and beersmith correction are telling me. I did not check it with a hydrometer. I crossed checked a few previous brews, and the beersmith correction and hydrometer always matched, so i stopped checking with both.

Since the gravity is now 1.004, i am way below what the style calls for. Not that i'm overly concerned with style, but i always seem to have this problem where my yeast over attenuates. It does not seem to matter what yeast I use. I have had over attenuation with other wyeast blends as well as S0-4 and S0-5.

Does anyone else have this "problem"? Is there anything i can do differently? Or am i doing something wrong?
 

eastoak

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use a hydrometer regardless what you've done in the past with a refractometer.
 

osagedr

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Need a hydrometer reading to be sure. Don't forget to correct for temperature.

I've used that strain dozens of times, it attenuates well but I would be shocked to see 1.004 from the grain bill and mash temp you described. If it really, truly is 1.004 on your hydrometer corrected for temps, I'd wonder about your mash temperature reading, and about an infection.
 
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centralpabrewer

centralpabrewer

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This was in the primary for 14 days at about 53F, give or take a degree or so.

I don't think i have an infection, the beer smells and tastes ok, although I know that may not mean much. Maybe my mash temps were lower than 150F. I presume that would make it ferment out dryer and as a result i would have a lower FG???

i tried to take a hydrometer reading but could not get enough of a sample in my thief. It looked to be around 1.010 at 55F. Better than 1.004. I checked my refractometer with distilled water and it read dead on 0 and it has ATC.

I also checked at SeanTerrill.com and that gave me 1.009.

I just put it down to lager for 45 days. I will check it when i rack to the keg.

Thanks everyone for the feedback
 
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centralpabrewer

centralpabrewer

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Today I racked my Pilsner to a keg. Final Gravity was 1.007. Apparent attenuation is 87%.

I also brewed a Belgian Golden Ale last week. Original gravity was 1.079, after 10 days in the primary, SG shows 1.008, apparent attenuation of 89%. This one I mashed at 150F for 75mins, then raised the temperature of the fermenter from 65F to 80F over the 10 days.

Looking back at a lot of my beers over the last year or so, most of them have an apparent attenuation of between 75 and 90%, but a few as low as 65%.

Maybe I need to start fermenting in a better bottle or glass carboy and take my buckets out of the equation. Anyone have any thoughts?
 

duboman

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centralpabrewer said:
Today I racked my Pilsner to a keg. Final Gravity was 1.007. Apparent attenuation is 87%.

I also brewed a Belgian Golden Ale last week. Original gravity was 1.079, after 10 days in the primary, SG shows 1.008, apparent attenuation of 89%. This one I mashed at 150F for 75mins, then raised the temperature of the fermenter from 65F to 80F over the 10 days.

Looking back at a lot of my beers over the last year or so, most of them have an apparent attenuation of between 75 and 90%, but a few as low as 65%.

Maybe I need to start fermenting in a better bottle or glass carboy and take my buckets out of the equation. Anyone have any thoughts?
Have you calibrated your thermometer lately? Maybe you are mashing lower than you think?
 

PaulVikingAles

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Definitely check your thermometer. We were using a digital thermometer for 6 months and our final gravity was always higher then expected. We finally bought a lab grade thermometer and found out the digital was off by 6 degrees. Our 148 to 152 mash temps were really 154 to 158. Your thermometer could be reading high. Definitely calibrate that before making any other adjustments.
 

stpug

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I'd like to know about your mashing process a little bit more. I'm assume that you batch sparge, maybe double batch sparge?
 
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centralpabrewer

centralpabrewer

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Typically I will do a single infusion mash for 60-75 minutes. Then mash out for 10min, then batch sparge once
 

stpug

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Good process there. I was wondering about excessive enzymatic activity (beyond what you formulated in the recipe) by having a slow drain, slow sparging, and no mashout. HOWEVER, you DO mashout (168 grainbed for 10 mins?) so that excludes my idea. If I think of anything else I'll certainly post back.

Definitely check your thermometer at high temperatures as well.
 

PaulVikingAles

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Did you end up taking hydrometer readings? You listed 1.007 for the pilsner and 1.009 for the Belgian. I'm not sure I would necessarily call the these over-attenuated if those are accurate hydrometer readings. It sounds like you properly pitched good healthy yeast starters, properly controlled temps, aerated well, added yeast nutrient, and have a solid brewing process. Nice job. If you were still at 1.004 or lower I would review your mashing temps and thermometer. You still should do it anyway.
 
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centralpabrewer

centralpabrewer

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I checked FG with both hydrometer and refractometer, and they read the same. I guess i see the estimated numbers per the style in beersmith and assume i am way under. I'm not brewing for anyone's benefit but my own and I think my beer is really good. Just trying to improve my processes. Thanks for the suggestions and feedback, it is most appreciated.
 

PaulVikingAles

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If you like you beer than that I what is important. We never end up with gravity's that match beersmith and we don't even think about it. We allow the yeast to do there thing and it ends up where it ends up. We only worry if we are high. You can always trying raising you mash temp by a degree at a time if you are concerned with hitting FG. I think you are doing good and your results show it. Nice job!!
 

Komodo

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I don't know about Beersmith, but iBrewmaster uses manufacturers yeast attenuation %s which I think are always low. There's a whole thread about that somewhere around here. I tend to use a lot of the same yeasts and adjust each yeasts attenuation based on my past experience. Also, if it's a new yeast, then I search here for others posted attenuations, and also in places loke the White Labs yeast review pages. If I can find 3-4 that seem fairly close I have no problem adjusting it up (usually).

This will all help with forulating future brews and hitting numbers more ckosely.
 
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