First AG Boil

[thebull]

I've built a ten gallon system, but will try a five gallon boil first. Working on an IPA clone to try first. My question is about the hops. The recipie calls for 8.75 AAU of Centennial and 5 AAU of Kent Golding hops. As I understand the formula for converting AAUs to ounces, I would need slightly more than one ounce of Centennial if sold at 8.5% aroma and one ounce of Kent Golding sold at 5.4%. According to Midwest Suppy, that is the percentage numbers of their in stock hops. This seems a little light on hops compared to my prior extract kit boils.

 

[sause]

With AG brewing you are doing a full boil meaning you are boiling at least 5 gallons at one time. In comparatino with extract where most people boil only 2-3 gallons, with the same amount of sugar in each. So the SG of a full boil is lower than the SG of the paritial boil. Hop oil extraction is dependent on SG, with a full boil you get better extraction. So you will use less hops than you normlly would when doing all grain. That and there is no flavor additions listed there.

 

[disaffected]

Your hops calculations seem correct.

AAU (Alpha Acid Units) = HBU (Homebrew Bitterness Units) = %AA times X ounces of hops

So solving for X, you calculate the weight of hops you need as
X = AAU / AA%

If a recipe calls for 8.75 AAU's of Centennial hops and it has a AA% of 8.5, then
X = 8.75 / 8.5
X = 1.029 ounces

If you need 5 AAUs of Kent Golding and it has an AA% of 5.4, then
x = 5 / 5.4
x = .926 ounces

You could just round them both off to an ounce. It would be plenty close enough, the difference being undetectable to humans.