Natdavis777
Well-Known Member
I recently purchased some hop extract from Yakima Valley Hops. For the price of 100g, it is definitely a steal. After drawing up my syringes, I wondered what the IBU contributions would be.
I then began further research, only to find many other people had the same question. During my downtime at work today, I tried figuring out the most precise method of calculating what my IBU contribution would be with a certain mL at a certain time. Some of the formulas I used included computing AAU(g), IBU conversion from AAU, and the formula most extract suppliers provide [Extract mL=AAU(g) x Extract density(g/mL)].
Eventually finding the density of hop extract on a website, I confirmed last night on my scale that extract density is 1g/mL (the website stated 1.05 @ 60C). Meaning in my 10mL syringe (after subtracting weight of the syringe and cap itself) 10mL of hop extract weighed 10g around 50C.
After a good amount of number punching, I basically came to a conclusion that IBU=Extract mL x 1000 X U / Volume (L). "U" refers to hop utilization, which a chart can be found here. This chart gives a coefficient relating to boil time and wort SG.
This is 2015 though, and we dont need paper to work out equations. There are calculators for that. I found these calculators a little confusing until I starting running numbers through them. And that is why I wanted to help clear the air.
http://brewbrothers.biz/Hop-Jizz-Extract-Calculator is pretty straight forward. Put in your info and it tells you what mL to inject. But is it trustworthy? That was my initial thought. So I then went to HopUnion.
https://www.hopunion.com/brewing-calculators/ The first calculator is what I used to calculate IBU contribution. It gives some instructions, but I feel they are not 100% clear. To use this calculator, first input the desired IBU in the first row (duh). In the BBL row, for 5 gal put .16, 10 gal put .32, etc. Efficiency (which the instructions are mucky on), input the "U" value explained above, but instead of a decimal, put as a percentage (23 instead of .23). This will then give you the GmAA, or grams of AA to be added. Since density is 1g/mL, it basically equates to how many mL of extract to add the the boil.
I then began further research, only to find many other people had the same question. During my downtime at work today, I tried figuring out the most precise method of calculating what my IBU contribution would be with a certain mL at a certain time. Some of the formulas I used included computing AAU(g), IBU conversion from AAU, and the formula most extract suppliers provide [Extract mL=AAU(g) x Extract density(g/mL)].
Eventually finding the density of hop extract on a website, I confirmed last night on my scale that extract density is 1g/mL (the website stated 1.05 @ 60C). Meaning in my 10mL syringe (after subtracting weight of the syringe and cap itself) 10mL of hop extract weighed 10g around 50C.
After a good amount of number punching, I basically came to a conclusion that IBU=Extract mL x 1000 X U / Volume (L). "U" refers to hop utilization, which a chart can be found here. This chart gives a coefficient relating to boil time and wort SG.
This is 2015 though, and we dont need paper to work out equations. There are calculators for that. I found these calculators a little confusing until I starting running numbers through them. And that is why I wanted to help clear the air.
http://brewbrothers.biz/Hop-Jizz-Extract-Calculator is pretty straight forward. Put in your info and it tells you what mL to inject. But is it trustworthy? That was my initial thought. So I then went to HopUnion.
https://www.hopunion.com/brewing-calculators/ The first calculator is what I used to calculate IBU contribution. It gives some instructions, but I feel they are not 100% clear. To use this calculator, first input the desired IBU in the first row (duh). In the BBL row, for 5 gal put .16, 10 gal put .32, etc. Efficiency (which the instructions are mucky on), input the "U" value explained above, but instead of a decimal, put as a percentage (23 instead of .23). This will then give you the GmAA, or grams of AA to be added. Since density is 1g/mL, it basically equates to how many mL of extract to add the the boil.
