Calculating Quantity of Hops Required When the Recipe Only States Required IBU

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Binkie Huckaback
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Calculating Quantity of Hops Required When the Recipe Only States Required IBU

Post by Binkie Huckaback » Thu Oct 14, 2021 6:49 pm

I'm hoping to make David Heath's Raspberry Philly Sour recipe this weekend, but rather than give a quantity of hops, he just gives the IBU required and to be honest, I'm at a bit of a loss, especially as the boil is only thirty minutes.

The first addition is of centennial at thirty minutes and should be or produce 6 IBU. The second addition is again of centennial at five minutes and be or produce 1 IBU, the total being 6 IBU.

I've had a poke around the internet and found a calculator on Brewer's Friend which, assuming a 19 litre batch with hop utilisation at 100% (I have no idea what mine is), that with my hops being 9.5%, I'll only need 5.6g of hops to produce an initial IBU of 6.03 and 4g of hops to produce 1.02 IBU.

As I've never made a 'sour' beer or only used a thirty minute boil, I've no idea if this might be just about right.

Any advice or input would be gratefully received.

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Re: Calculating Quantity of Hops Required When the Recipe Only States Required IBU

Post by IPA » Fri Oct 15, 2021 7:08 am

Use Graham's Beer Engine on this forum.
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Re: Calculating Quantity of Hops Required When the Recipe Only States Required IBU

Post by vacant » Fri Oct 15, 2021 8:34 am

1.02 IBU? Let me see, with 9.5% you'll need 4.254632g, wait, it's Friday so that will be 4.254631g :wink:

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Re: Calculating Quantity of Hops Required When the Recipe Only States Required IBU

Post by Binkie Huckaback » Fri Oct 15, 2021 9:05 pm

Thanks Guys. IPA - that's what I thought, but I couldn't find a way to alter the boil duration. I assumed that would have an impact on utilisation.

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Re: Calculating Quantity of Hops Required When the Recipe Only States Required IBU

Post by Northern Brewer » Sat Oct 16, 2021 11:31 am

Binkie Huckaback wrote:
Thu Oct 14, 2021 6:49 pm
The first addition is of centennial at thirty minutes and should be or produce 6 IBU. The second addition is again of centennial at five minutes and be or produce 1 IBU, the total being 6 IBU.
6+1=6???

You don't get 100% utilisation even at 60 min, and 30 min will give you ~75% of the bitterness of a 60 minute boil.

Brewtarget says for 6IBU at 30 minutes you need 6.7g of 9.5% alpha and 2.4g at 10 minutes for 1IBU.

You can then pro-rata those amounts for different IBUs or alpha contents.

Philly Sour is interesting, before using it I suggest you look at the thread on HBT, and in particular at Bryan Heit's articles, the first is more general background, the second is about how to get the best out of it, it's a bit more finicky than Saccharomyces :

http://suigenerisbrewing.com/index.php/ ... tent-wars/
http://suigenerisbrewing.com/index.php/ ... illy-sour/

He also compares it to Sourvisiae, which is a Saccharomyces that has had acid-making genes added, so isn't available in Europe, it's cleaner and more acid :
http://suigenerisbrewing.com/index.php/ ... throwdown/

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