Working Out Bitterness

[hazz20]

Hey guys, been reading john palmers how to brew and was wondering about working out the bitterness required for a certain recipe. Am getting a bit confused with AAU's and IBU's, and as his book is in ounces and we use grams, i'm a bit lost.
Any help would be appreciated!

Thanks,

Hazz

 

[Gavo]

You can use the brew calculators link on the top if the page to convert from ounces to grams plus many other useful calculator there. You could also download a trail version of beersmith http://www.beersmith.com/ I have found this very useful and great to use when calculating bitterness levels and making a new recipe.

 

[Jamz]

IBU is a metric unit of measure (milligrams of alpha-acid per litre), the yanks just perverted the formula to make it work with their ounces and gallons. Below is the same formula but written for use with metric units:

IBU=weight_of_hops(g) x %alpha_acid x 1000 x utilization_factor / batch_size(L)
(taken from here)

I've never bothered with using alpha-acid units for anything, but I believe its just the weight of the hops (in ounces) multiplied by the alpha-acid percentage. So if you want to use grams instead divide by 28.35 at the end since there's approximately 28.35 grams per ounce.

AAU = weight_of_hops(g) x %alpha_acid / 28.35

Does this help?

Its good to understand the concepts but in the end, it really is easier to get some brewing software to do the calculations for you

 

[hazz20]

Thanks guys, a little clearer now. Slowly getting there.

Hazz