Crisis in the brewery: Low attenuation, sweet beer

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Houdini
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Crisis in the brewery: Low attenuation, sweet beer

Post by Houdini » 2 years ago

Hello all,

When I switched from extract/partial mash to BIAB about five batches ago, my beer went from good to sweet and unattenuated. I've ruled out yeast health and fermentation temperature control, which leaves wort fermentability. I recalibrated my mashing thermometer. It was reading 4 degrees F too low (so I was mashing 4 degrees above the target temperature). I've been mashing at 150 degrees for 90 minutes. I don't have means to measure PH - I tried the paper strips but did not believe the readings (they never changed color). I'm using reverse osmosis de ionized water with 1 tsp of calcium chloride per 5 gallons added back. Any suggestions? I don't want to waste any more time and money on less than excellent beer. I'm using recipes that are proven for traditional three-vessel brewing with some additional malt to compensate for lower efficiency.

Thanks,
Houdini
Last edited by Houdini on 09 Mar 2015, 00:49, edited 1 time in total.


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Post by joshua » 2 years ago

Houdini,

Could you tell us what your Original Gravity, and Final Gravity was???

The "sweet" taste indicates there was no Fermentation.

As long as the mash temperature was above 140F and below 176F, it should have been a good Mash.
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Post by Houdini » 2 years ago

1.076 to 1.039
1.054 to 1.030
1.061 to 1.032
Measured with a refractometer with no correction for alcohol

Fermentation obviously started, just ended sooner than I was expecting


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Post by joshua » 2 years ago

Houdini,

Those Numbers look good for around 5-7 days of Attenuation.

Did you brew a Lagar, or an Ale??

What Fermentation Temperature was used???

With the SG dropping about 30 Points shows the Yeast was Working well, and should have Bottomed around 1.012-1.0120 in about 18 days to 21 days.

JMHO, YMMV
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Post by Houdini » 2 years ago

Those are final numbers given several extra weeks to finish with no additional progress. As previously stated, I've ruled out yeast health and fermentation temperature control. I've brewed 30 batches of extract beer with no issues. It has to be related to mashing.


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Post by joshua » 2 years ago

Houdini, then the only thing can be is the Mash Temperatures spent quite a few Minutes above 158F, and allowed the Alpha Amylase to make Long Sugars that were un-fermentable.

see http://www.howtobrew.com/section1/chapter3-5.html from John Palmer.

Another couple of question, was the Mash at full Volume(water to Grist above 4L/Kg or 2Qt/pound) and was the mash compacted or stirred periodically???
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Post by Houdini » 2 years ago

Yes, I was mashing at full volume and I did stir periodically.

It is possible that a significant portion of the mash was over 158 for a significant period of time. Adjusted for miss-calibration I was targeting 154 degrees. My thermometer could have read 152 (really 156) without me taking corrective action. The heat source is not immediately adjacent to the thermometer probe (hence the stirring) so that could easily have put me over 158.

Thanks for the feedback!

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Post by mally » 2 years ago

I'm not sure what yeast you used Houdini, but the data doesn't read too bad.
If your gravity readings from the refractometer are as you say uncorrected for alcohol I have concluded the following from it;

Brew #1) 1.076 - 1.039 is equal to 18.5 Bx - 9.9 Bx, therefore, F.G. was 1.017, 7.1% ABV, 77% attenuation (corrected for alcohol).
Brew #2) 1.054 - 1.030 is equal to 13.4 Bx - 7.5 Bx, therefore, F.G. was 1.015, 4.7% ABV, 71% attenuation (corrected for alcohol).
Brew #3) 1.061 - 1.032 is equal to 15.0 Bx - 8.1 Bx, therefore, F.G. was 1.015, 5.5% ABV, 74% attenuation (corrected for alcohol).

Do those Brix readings look correct?

They all seems a little high F.G. but nothing looks major.
As Josh said, maybe you have a lot of unfermentables due to mash temp that is keeping the final gravity that high.
Last edited by mally on 09 Mar 2015, 02:02, edited 1 time in total.
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Post by Lars » 2 years ago

Hi houdini. Your mash ph would be way too high with ro water unless your grainbill includes 10%+ dark malts or unless your addin sauermalz. I use ro and ph is well above target unless the mash is acidified somehow

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Post by thughes » 2 years ago

My money is on mash temps too high.....

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