Hops - Double alpha acid = half quantity?

[nicowk]

Is it that simple?

I'm going to follow Greg Hughes Amarillo single hop recipe, which has Amarillo hops with an alpha acid of 5.5%, having a look on Malt Miller, their Amarillo harvest is 10.8%, so pretty much double.

Does this simply mean using half the quantity of hops for the same affect?

I'm still learning, but if this is the case, is the alpha acid just for bittering, so the aroma hop additions would still be the same quantity?

Thanks

 

[DoctorMick]

For bittering (early additions) yes, it's that simple. For flameout additions the AA %age doesn't matter because you won't extract any AAs (in theory anyway but it does depend on how quickly you cool...a lot of people cool to 80c before adding flameout and leave to steep as this extracts 0 AAs), it gets a bit more tricky with the flavour additions (i.e. 10-15 minute additions) because the flavour doesn't come from the AAs so you'd probably want to use the same quantity as in the recipe to get the required level of flavour from the hops. It'd be worth plugging the recipe in to some software and set the AAs of the hops to 10.8% and then tweak the bittering addition until you get the original IBUs of the recipe.

 

[nicowk]

Thank you, good info. I'll have a tweak of the recipe in brewers friend.

 

[Cqr]

I brewed that one, very nice indeed