I ran a ****ter recipe through the tastbrew.com recipe calculator, and
tried it with two different boil sizes: 2.5 gal (which I used to do),
and 5.0 gal (which I do now that I have a bigger kettle).
Here's the recipe:
4 lb light syrup
3 lb dark dry extract
0.5 lb roasted barley
0.5 lb chocolate
0.5 lb crystal 60L
3.4 oz 5% alpha pellets (boiled 60 min)
1.5 oz 6% alpha whole hops (boiled 5 min)
This is for a 5-gal batch.
When I run the calculation for a 5-gallon boil, I get numbers that seem
to be right: 17 AAU, utilization=.238, 66.5 IBU. The AAU value
checks out, the utilization for the bittering hops seems reasonable
by comparison with a table of Tinseth values, and the IBU is what I
get if I do 75*17*.238/5.
But when I cut the boil volume to 2.5 gal (while keeping the batch size
to 5 gal), the results seem crazy. I get a utilization of 0.047, which
seems crazy -- the Tinseth value is more like .147. And the IBUs go up
to 86.2, which would imply a utilization of greater than 1.
Am I just confused, or is this a bug in the software that I should
re****t to the guy who runs tastybrew.com?
If you want to see the strange behavior, it happens if you just go to
http://www.tastybrew.com/calculators/recipe.html
and type in the
following simpified recipe:
7 lb light syrup
3.4 oz 5% alpha pellets (boiled 60 min)
I don't know if (a) it's a bug in the software, (b) there's something
about brewing that I don't understand, or (c) I'm misunderstanding how
to use the software.
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