Author Topic: hop calculation  (Read 4007 times)

Offline pelle.hofffman@telia.com

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hop calculation
« on: January 24, 2010, 01:32:10 AM »
Hi,
When I calculate northern brewer (10,5% alfa) in BeerSmith, 29 grams, 60 minutes boil, 25 litres volume, the IBU should be around 44. But it only shows 28,7. If I take away all grains from the calculation the IBU turns into 43,9.

The other hops with less boiltime stays the same.

How come??

/Pelle

Offline BeerSmith

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Re: hop calculation
« Reply #1 on: January 24, 2010, 10:00:10 AM »
Malt in the boil actually results in lower hop utilization, and the higher the original gravity of the  boil, the lower the hop utilization will be.  This is why extract brewers doing partial mash boils generally require more hops than comparable recipes that are full boils.

Taking this to the extreme you can actually mix hops with water to create hop tea for maximum hop utilization, but generally I recommend using at least some malt as using water alone can create some off flavors.

Cheers,
Brad
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Offline pelle.hofffman@telia.com

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Re: hop calculation
« Reply #2 on: January 26, 2010, 04:51:27 AM »
Ok,

So if I am lautering 30 litres, the first litres will have a higher SG than the last. Is it a good idea to boil the fist 15 litres i one pot and the last 15 in another, and boiling the hop only in the last one?

It sounds like a good idea, but maybe more difficult to hit the required IBU..

Thanks
Pelle

Offline MaltLicker

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Re: hop calculation
« Reply #3 on: January 26, 2010, 05:49:50 AM »
Separation may maximize IBUs due to the lower gravity, but isomerization of hops and those iso-humulones in the wort assist in the coagulation of proteins and also provide some preservation qualities and flavor stability of the final product, so I would not recommend that path.  Any sugar or DME could be added in the final 20 minutes. 

 

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