OG low on extract brewing

[Methose]

The past two times I've brewed (which is only out of a total of 6), my OG has come out a good bump lower than what was calculated from the site of my LHBS. I brewed one as a partial boil and one as a full on my friend's turkey fryer brewing setup.

I brewed a Foreign Extra Stout +1 extra pound of LME, which came out at 1.054 @ 85F as a partial boil of 3 gallons initial boil and adding the remaining up till 5 as cold water in the fermentation bucket. I did do a late extract addition of about half the LME.

I brewed an American IPA which came out at 1.046 @ 86F. This was a full boil starting at about 6 - 6.5 gallons and ending right on target of 5 gallons. I also did a late addition extract addition of about half the LME.


Any thoughts on what might be causing the OG to come out lower than what the calculator says?

 

[Pakkasso]

I would think your LME would be a known quantity in the OG calc, so the discrepancy probably comes from your grain steeping process. What did you steep them in? How did you sparge them? The stout kit assumes an efficiency of 75% efficiency. I'm pretty sure I don't get that (ever).

 

[tooldudetool]

I wouldn't expect much of a bump in gravity from the steeping grains. The IPA only has a pound of dark munich, which won't give you much more than 5 points or so (like from 1.060 to 1.065), so you could leave it out completely and still get a 1.060 wort. More likely, your wort isn't mixed thoroughly before you are taking your hydrometer sample, the heavy stuff tends to settle to the bottom rather quickly. With malt extract, the sugar is there, whether you can measure it or not. For the IPA recipe: every pound of LME yields 37 points (1.037 gravity when rehydrated to 1 gallon, not 1 gallon of water added to it), multiply that by 8 lbs, 37 x 8 = 296 points. Divide 296 by your final volume of 5 gallons, and you get 59.2, or an OG of 1.059. At some point in my extract brewing I accepted this concept, and stopped taking OG measurements all together, unless I had a high amount of steeping grains, although they can be calculated pretty accurately too. The point being, if you added 8 gallons of LME to your final volume of 5 gallons of wort, it was at least 1.059 or greater, whether you were able to measure it or not.

 

[CBMbrewer]

Don't know if you took this into account but,
If the hydrometer reading from the stout was 85F it wold be 1.057 in actuality
if the hydrometer reading from the ipa was 86F it would be 1.049
And be sure to aerate/mix your final volume thoroughly and take your reading from that.

 

[Methose]

I would think your LME would be a known quantity in the OG calc, so the discrepancy probably comes from your grain steeping process. What did you steep them in? How did you sparge them? The stout kit assumes an efficiency of 75% efficiency. I'm pretty sure I don't get that (ever).

I steep the specialty grains at 158F for 20 mins, typically in a standard hop-sock, but I actually forgot one and the LHBS was closed on brewday so I had to sub for a pair of knee-high pantyhose

 

[Methose]

Don't know if you took this into account but,
If the hydrometer reading from the stout was 85F it wold be 1.057 in actuality
if the hydrometer reading from the ipa was 86F it would be 1.049
And be sure to aerate/mix your final volume thoroughly and take your reading from that.

I used brewr to calculate the head differential, but that still came off at 1.057 when it should have been 1.070 according to my calculations after adding the extra pound of LME.
More or less just wondering if I am doing something wrong, or could be doing something better.

 

[Methose]

The point being, if you added 8 gallons of LME to your final volume of 5 gallons of wort, it was at least 1.059 or greater, whether you were able to measure it or not.

That does make me feel better, I was hoping I wasn't somehow shorting myself. I'm much more in it for the flavor and fun, but at some point I'll likely want to brew an imperial and would like it to hit the target.

 

[duboman]

As long as you continue to brew extract with top off water chances are that you will never hit the desired OG due to the inability of getting a thorough mix between the top off water and wort. It is a common problem and there is even a stickie about it by Revvy.

If you use a known quantity of extract and hit your volumes properly the OG will always be what the recipe states regardless of what you measure.