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sluggerdog

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I was just going through beertools.com using their recipe calculator and I noticed something a little funny..

I was playing with the hops, I have at the moment some Hallertau pellets (6.6 %AA) I placed in 45gms on a 60 minute boil and it comes out at 19.0 IBU then I went to the grumpys calculator and put in 19 as the IBU, 6.6AA and a 60 minute boil and it tells me to use approx 21 grams of hops for this amount of bitterness.

45 to 21 grams is a big difference...

Anyone know of somewhere I could check out which is more accurate some how?

Cheers



http://www.grumpys.com.au/HopWeight.php3
http://www.beertools.com/html/calculator.php
 

kook

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Is this with the same volume of liquid with the same sugar contents and water properties?

Edit - I'm not sure how that grumpys calculator can be accurate considering hop utilization depends on the contents of the liquid not just the volume of it!
 

sluggerdog

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Yeah grumpys doesn't account for other ingredients, just a batch size.

I was using the correct ingredients on beertools.com
 

Guest Lurker

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The Grumpies calculator assumes a default utilisation which is way high, but gives you the opportunity to put in an accurate utilisation which you go and look up from Tinseth or somewhere, based on your boil gravity. Until I worked that out I thought I was a hophead, brewing beers with huge IBUs predicted by the Grumpys calculator and finding them not that bitter. I imagine the beertools one takes account of boil gravity, so believe that one.
 

sluggerdog

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Thanks Guest Lurker

Funny thing about what you said though is the Grumpys said to use only 21 gms and Beertools.com said to use 45 gms to get the same amount of bitterness.

I think I'll go with beertools.com as you have to account for all the ingredients

Thanx
 
J

Jovial_Monk

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The gravity of the boil has a big impact on hop utilisation, many published recipes (e.g. the Brew Real English Ale and Brew Classic European Beers) assume a higher than realistic utilisation figure for the stronger beers. I aim to get a realistic recipater on my website soon.

Jovial Monk
 

sosman

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45 to 21 grams is a big difference...
Yes it is but I think Noonan or Daniels mentions somewhere that 100% variation in utilization between breweries is observed (I take that to mean it can vary by a factor of 2).

For a wort with BG of 1.033 and boil volume of 30L I get 16 BU from 21g @ 60 min. I am using Tinseth's calcs with his default constants.
 

Guest Lurker

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sluggerdog said:
Thanks Guest Lurker

Funny thing about what you said though is the Grumpys said to use only 21 gms and Beertools.com said to use 45 gms to get the same amount of bitterness.
Yes, thats what I said, maybe I didnt explain well enough.

Grumpys have a default utilisation which is very high. This means they calculate you can get a lot of IBUs out of a small amount of hops. So their calculator will tend to give a lower weight of hops.

The biggest control on hop utilisation (how much bitterness you extract from a certain amount of hops) is not the shape of the kettle, whether the hops are in a bag, whether the hops are plugs or pellets. The biggest control is the gravity of the boil (how much malt/sugar/water you have in the pot.

Most people using the Grumpys forum probably are doing a small boil, say 2 kg of DME in 6 l to fit in an 8 l pot, = a boil gravity of 1.100

Looking up the Tinseth table in How to Brew, boiling for 60 mins, at a gravity of 1.100, the hop utilisation is 0.147, ie 15% extraction.

The default value in the Grumpys calculator for a 60 min boil is 32%. So, in this particular case, if you work out your hop weight, using the Grumpys calculator and the default values, your hops will only give you half the IBUS that you wanted.

Moral of the story - if using the Grumpys calculator, look up an actual utilisation for your gravity instead of using the default.
 

sluggerdog

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Cheers Guest Lurker

Got ya now, thanks for the helpful info!
 

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