Low FG - Extract and Specialty Grains

[hoppinghare]

Hey Brewers,
This is my first post on HBT although I have been constantly absorbing its vast wealth of knowledge since my first batch brewed in January. My first beer - Porter - went off without a hitch and has been very popular among my friends. This second beer may be a different story.

The recipe is a Blonde Ale from Dan's Homebrewing in Vancouver, BC.

7lb Pale Malt Extract
0.65lb Wheat Malt
0.65lb Pilsner Malt
7.25 AAU Cascade/Willamette - 60min
.4oz Cascade/Willamette - Finish
American Ale Wyeast #1056

Grains were steeped at 155deg for 45minutes (I think. Didn't write the length down).

My OG was 1.048 (low based on BeerSmith estimate - 1.056). FG was 1.006

My question (finally) is how did I end up with such a low FG and will the beer wind up thin and dry? Generally, how can a simple extract + specialty grain recipe wind up so far from the target gravity readings?

Thanks for any info!

 

[knyland]

how many gallons was the batch? Did you add top up water after your boil was done? How will did you mix said top up water after adding it to the carboy or bucket?

 

[hoppinghare]

I did add top up water to 5 gallons and vigorously shook for 1 minute, however my OG was taken before shaking. What I am now trying to figure out is if I was topped up using imperial or standard gallons.

I asked someone at my Local Homebrew shop about my FG and they said that the beer can reach as low as 1.004 in some cases and to relax and have a homebrew. So, that's what I am doing now, but still interested to know more about what affects attenuation in extract + specialty grain brewing. Can the steeping have a significant affect on final gravity?

Edit:
Also now that I realize I did only top up to 5 US Gallons instead of 5 Imp Gallons, what are the effects?

 

[BradleyBrew]

what temperature did you mash your extract?

 

[hoppinghare]

The grains were steeped at 155deg F for 45minutes. Not sure what you mean by mashing the extract (LME)?

 

[duboman]

Your starting gravity reading is off because you got a bad mix of wort and top off water.

As for the final reading are you sre your hydrometer is calibrated? Did you correct for temperature? 1.004 is kind of low but not impossible

 

[ajf]

Technically, this isn't extract plus specialty grains. Wheat malt and Pilsner malt are both base grains which require mashing. As you steeped them at 155 for 45 minutes, you performed a mash.
As you took the OG after adding the top-up water, but before mixing, that would probably explain your low OG. If you want to get an accurate OG the next time, I would recommend stirring the wort rather than shaking it to mix the wort, as shaking is not a good way to mix the wort. After stirring and taking the gravity sample, you can shake the wort to add oxygen.
For the low FG, what temperature did you take the sample at? and did you apply a temperature correction to account for any difference in the sample temperature and the calibration temperature of the hydrometer?
Finally, have you tested (calibrated) the hydrometer by measuring some distilled water at the calibration temperature? If this reads less than 1.000, you need to add the difference to every reading. It is not uncommon for hydrometers to be off by a few points.

[edit] duboman beat me to it [/edit]

-a.

 

[Calder]

If you steeped the grains, you probably didn't get much out of them, since they need to be mashed. 1.048 is about right for the extract alone.

85%+ attenuation is high for an extract batch, but not impossible. What temperature did you ferment at? High temps will increase attenuation.

 

[hoppinghare]

Thanks Calder, ajf, and duboman for the feedback.

As ajf and duboman both suggested, I will definitely stir before taking the OG next time and then aerate after pitching.

Finally, have you tested (calibrated) the hydrometer by measuring some distilled water at the calibration temperature? If this reads less than 1.000, you need to add the difference to every reading. It is not uncommon for hydrometers to be off by a few points.

I have not calibrated the hydrometer, but will do so next chance I get to buy some distilled water. Maybe this is adding to the low FG reading.

Technically, this isn't extract plus specialty grains. Wheat malt and Pilsner malt are both base grains which require mashing. As you steeped them at 155 for 45 minutes, you performed a mash.

This was my thought as well despite the label on the recipe. Thanks for confirming.

What temperature did you ferment at? High temps will increase attenuation.

Fermented at between 18C and 19C. Wanted to air on the cooler side to avoid unwanted esters.