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 Home Brew Forums > Much lower OG than expected
05-09-2011, 04:18 AM   #1
davcjohn
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 Much lower OG than expected

I know several people have posted similar threads but no one seems to have the exact issues I seem to be having. I have just started formulating my own recipes after following several kits and never having issues coming close to the target OG and ABVs. I have been using Beer Calculus @ Hopville to do the math. Both times I have done this, I have ended up with fairly drastically different OGs than expected.

My first attempt was for a quad with a calculated OG around 1.09. I ended up around 1.065 but the beer attenuated more than expected and my target ABV was only off by about 1% in the long run.

This time I made an "Oktoberfest" in which I aimed for an OG around 1.065 (admittedly a little high for the style) for a 5.25 gallon batch but my OG just came in at 1.041 (adjusted for temperature of 70 degrees at time of measurement).

My grain bill is:

4# munich malt
3.5# pilsner 2 row
3.3# Briess Amber LME
.25 # Dark Crystal
I also made a 2 Liter starter with about 6oz of DME in it.

I did the math accounting for 5.25 gallons, I steeped for 30 minutes at exactly 155 degrees, I boiled about 4 gallons (which boiled down to around 3.25) before adding in the yeast starter and extra water, and stirred a decent amount before measuring to try and make sure the high gravity stuff was being measured too. I checked my hydrometer in tap water and got a .990 reading in slightly colder than room temp water.

Some how I am ending up with less than 50% mash efficiency. How is this possible and how can I correct it? Is it worth trying to salvage that potentially extra 1.5% abv by adding some disolved LME or DME?

I really appreciate the help.

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05-09-2011, 04:22 AM   #2
reim0027
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? Did you get cut off?

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05-09-2011, 04:24 AM   #3
freelunch
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Quote:
 Originally Posted by davcjohn I know several people have posted similar threads but no one seems to have the exa
From what we have so far, I would guess that the lower than expected OG might be due to a shortened or incomplete mash.

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05-09-2011, 04:33 AM   #4
davcjohn
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yeah i accidentally hit enter on the keyboard too early.

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05-09-2011, 04:36 AM   #5
bruin_ale
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Quote:
 Originally Posted by davcjohn yeah i accidentally hit enter on the keyboard too early.
He's saying that you only mashed for 30 minutes.. most of us are doing 60 and some are doing 90.. you also didn't mention if you were rinsing the grain at all. If not, you're leaving behind fermentables there as well.

05-09-2011, 04:39 AM   #6
davcjohn
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yes, i am rinsing the grain. I guess the longer mash would make sense and something to try. I don't remember how long I was mashing for with my pre self-recipe formulation brews, but the brew master's bible only suggests 30 minutes. Way too short huh?

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05-09-2011, 04:46 AM   #7
bruin_ale
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60 is the gold standard. Alot of the highly modified malts we get these days will fully convert much more quickly than that though. You can do an iodine test to check your wort for residual starch.

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05-09-2011, 04:46 AM   #8
GiraffeBrew
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Try some DME & get it up.

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05-09-2011, 04:51 AM   #9
freelunch
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Looks like I had a lucky guess! What was quoted was all that was available at first...

Appropriateness of mash duration can depend some on the quality of the crush (courser should be left longer), and perhaps even the temp targets used.

I use 60 minutes as my minimum right now, but haven't experimented any with shorter or longer mashes to determine what works best.

You could try longer to see if it improves your efficiency provided there are not any negatives to the longer brew time. Otherwise... increase grain amounts to compensate for lower efficiencies.

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05-09-2011, 04:52 AM   #10
davcjohn
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thanks for the advice. I will do an iodine test next time to check my mash and likely will end up keeping it mashing for longer. I guess for now I toss some disolved DME in there and try and bump the OG some. A potentially as low as 4% Oktoberfest is unnaceptable to me!

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