piperbrew

Recipes 

After listening to the Jamil Show on Oatmeal Stouts, I've decided to give Jamil's recipe a shot. I entered it into BeerSmith and noticed my IBU level is very low (28 IBU) compared to what it "should" be (36 IBU). Here is the recipe:

Batch Size: 6.00 gal
Boil Size: 8.71 gal
Boil Time: 90 min
Equipment: Brew Pot (7.5 gal) and Igloo Cooler (10 Gal)

Ingredients

Amount Item Type % or IBU
9 lbs 6.4 oz Pale Malt (2 Row) UK (3.0 SRM) Grain 72.87 %
1 lbs Oats, Flaked (2.0 SRM) Grain 7.75 %
12.0 oz Chocolate Malt (350.0 SRM) Grain 5.81 %
12.0 oz Victory Malt (28.0 SRM) Grain 5.81 %
8.0 oz Caramel/Crystal Malt - 80L (80.0 SRM) Grain 3.88 %
8.0 oz Roasted Barley (500.0 SRM) Grain 3.88 %
1.80 oz Goldings, East Kent [5.00 %] (60 min) Hops 28.1 IBU
1 Pkgs English Ale (White Labs #WLP002) Yeast-Ale

Beer Profile

Est Original Gravity: 1.055 SG
Est Final Gravity: 1.018 SG
Estimated Alcohol by Vol: 4.81 %
Actual Alcohol by Vol: 5.08 %
Bitterness: 28.1 IBU
Est Color: 35.3 SRM

I know Jamil uses ProMash and there's usually some variance, but the difference is huge and I can't figure out why. I don't want to over hop this beer because my BeerSmith measurements were way off. Any thoughts?

__________________
"I've had a pint of bitter and now I'm feeling better, and I'm out on the tiles. We're going down the rubbers and we're going to pull some scrubbers because we're out on the tiles."

-John Bonham

Suthrncomfrt1884

Recipes 

The differences wouldn't be that much. Are your hops the same AAU%? If not, you need to up the hops a little. Also, in an oatmeal stout, you probably won't notice a difference of 8 IBU's.

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He who drinks beer sleeps well. He who sleeps well cannot sin. He who does not sin goes to heaven.

Another HERMS rig...

piperbrew

Recipes 

The AAU% are the same (5%) as Jamil's recipe. I'm sure the beer will be fine even at 28% IBU, but I'm just curious as to why my recipe is that far off.

__________________
"I've had a pint of bitter and now I'm feeling better, and I'm out on the tiles. We're going down the rubbers and we're going to pull some scrubbers because we're out on the tiles."

-John Bonham

JLem

Recipes 

There are several different algorithms for estimating IBUs. BeerSmith allows you to choose between the Rager, Tinseth, and Garetz methods. Try switching these under Tools --> Options --> Bitterness and you'll see how much they can vary. It is likely that the method BeerSmith is currently set to is different from the one Jamil used in his.

I also discovered this when crafting my oatmeal stout - depending on which formula I used, the IBUs varied between 27 and 46. This prompted a whole thread on the subject that might help you understand the dilemma - http://www.homebrewtalk.com/f39/beer-smith-overhopping-103930/. I now keep BeerSmith set to Rager since it seems to correspond best to my interpretation of bitterness.

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Brewing blog at Brew by Brew

BeerPressure

Recipes 

Boil time in the book is 60 minutes also, you have 90 entered. that could make a difference.

piperbrew

Recipes 

I'll definitely check on what method my BeerSmith is set on.

As far as the boil time, it's at 90 minutes with a 60 minute hop addition based on the Jamil Show. I actually thought about bumping the hop addition up to 90 minutes with the start of the boil to increase the IBUs a little, but will probably keep it at 60.

EDIT: Rager method bumped the IBUs up to 33.6, so it looks like this was the main difference. Thanks for the advice.

__________________
"I've had a pint of bitter and now I'm feeling better, and I'm out on the tiles. We're going down the rubbers and we're going to pull some scrubbers because we're out on the tiles."

-John Bonham

jsullivan02130

Recipes 

Your batch size is 6 gallons.

__________________
"There is nothing in brewing so complicated that a little effort can't make even more complicated."

piperbrew

Recipes 

Oddly enough that's the batch size he gives. I was going to scale it down to 5 gallons once I figured out the IBU situation, but I don't know why Jamil sometimes provides recipes for 6 gallons. I figured he'd either do it for a 5 or 10 gallon batch, but I guess it's not a big deal to just scale it back for 5.

__________________
"I've had a pint of bitter and now I'm feeling better, and I'm out on the tiles. We're going down the rubbers and we're going to pull some scrubbers because we're out on the tiles."

-John Bonham

BeerPressure

Recipes 

I think he plans for 6 gallons so 5.5 make it into the fermenter and then there is 5 gallons after trub.

jamilz

Recipes 

Yes, that is the reason. All of the information on formulas, volumes, etc is in the book around page 40 or so in the section, how to brew these recipes.