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Old 07-31-2014, 02:48 AM   #1
OscarBrau
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Default Attenuation

I'm starting to learn more about beer terms, and I have a question about attenuation. I understand that its the amount of sugars converted by the yeast, but it seems like some yeasts go far beyond the attenuation %. For instance, I made a bitters using a low attenuation yeast (wyeast 1469 67-71%). However, the final gravity dropped to 1.006 from OG 1.043, which is a large drop. What am I not understanding? If it helps, it was the Innkeeper extract kit from NB.

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Old 07-31-2014, 10:45 AM   #2
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Quoted attenuation numbers are good for relative comparison of strains, but not something that should be counted on to predict FG. Recipe is a much greater determinant of attenuation than yeast stain. 1.043 to 1.006 (86% AA) is pretty huge, but given the pound of corn sugar that the recipe appears to include, it doesn't seem out of the realm of possibility.

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Old 07-31-2014, 01:08 PM   #3
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Recipe has a big impact on attenuation, as stated above. Also, mash temperatures (if brewing all-grain) will impact it, or even if you are using extract vs. all-grain.

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Old 07-31-2014, 01:15 PM   #4
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I don't know if this will be useful but Temperature has its own influence on the gravity measurement. Hidrometers are normally calibrated to be used at about 59 F, and when used at room temperatures above, a small diference should be added. However if for some reason (summer for instance) you are reading gravity at higher room temperatures than 68 degrees, the difference will increase and will be significant. In the case of a very warm room, the point to be added might increase to 2 or 3

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Old 07-31-2014, 01:28 PM   #5
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Aside form temperature correction be sure your hydrometer is calibrated. Take a reading at 68oF in distilled water and it should read 1.000. If not then adjust your readings up or down accordingly.

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Old 07-31-2014, 01:47 PM   #6
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Check at the bottom of the card inside your hydrometer for the calibration temperature. 59°F and 68°F are common calibration temperatures. Depending on where the hydrometer was purchased you could also have a calibration temperature that is in Celsius.

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