Progfan2010
Active Member
I´ve been reading the section "how to measure hops " in chapter 5, pages: 54-60 and a few questions come to mind.
I have trouble understanding the section about utilization. I´ll paste the text here:
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Utilization
The utilization is the most important factor. This number describes the efficiency of the isomerization of the alpha acids as a function of time. This is where a lot of experimentation is being conducted to get a better idea of how much of the hops are actually being isomerized during the boil. The utilization numbers that Tinseth published are shown in Table 7. To find the utilizations for boil gravities in-between the values given, simply interpolate the value based on the numbers for the bounding gravities at the given time.
For example, to calculate the utilization for a boil gravity of 1.057 at 30 minutes, look at the utilization values for 1.050 and 1.060. These are .177 and .162, respectively. There is a difference of 15 between the two, and 7/10ths of the difference is about 11, so the adjusted utilization for 1.057 would be .177 - .011 = 0.166.
The Utilizations for 60 minutes and 15 minutes at a Boil Gravity of 1.080 are 0.176 and .087, respectively. Inserting these values into the IBU equations gives:
IBU(60) = 9.6 x .176 x 75 / 5 = 25 (rounded to nearest whole number) and
IBU(15) = 4.6 x .087 x 75 / 5 = 6
Giving a grand total of 31 IBUs.
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The main question I have is: How am I supposed to know what the boil gravity will be at minute 15, 30 or 60 or "X" when I am trying to design a beer?. If I am trying to design it from scratch (with no software help whatsoever) and want to figure out how bitter the beer will be, and find out the IBUs, how should I do it then?. If the IBUs calculation depends on the gravity of the boil, then it´s impossible to accurately (or at least a solid number) calculate the IBUs. Am I wrong?. I should be wrong, otherwise reaching a particular IBUs level would be erratic for every brewer.
Also, What is the boil gravity?. Is he meaning I need to measure the gravity of the wort while its at the 30 minute boiling time?.
Bottom line; I want to be able to set the amounts of malt (and kinds of malt), temperatures, and hops on paper. How can I calculate the IBUs (Utilization specifically) without waiting until boiling time?.
I have trouble understanding the section about utilization. I´ll paste the text here:
""""""""""""""""""""""""""""""""""""
Utilization
The utilization is the most important factor. This number describes the efficiency of the isomerization of the alpha acids as a function of time. This is where a lot of experimentation is being conducted to get a better idea of how much of the hops are actually being isomerized during the boil. The utilization numbers that Tinseth published are shown in Table 7. To find the utilizations for boil gravities in-between the values given, simply interpolate the value based on the numbers for the bounding gravities at the given time.
For example, to calculate the utilization for a boil gravity of 1.057 at 30 minutes, look at the utilization values for 1.050 and 1.060. These are .177 and .162, respectively. There is a difference of 15 between the two, and 7/10ths of the difference is about 11, so the adjusted utilization for 1.057 would be .177 - .011 = 0.166.
The Utilizations for 60 minutes and 15 minutes at a Boil Gravity of 1.080 are 0.176 and .087, respectively. Inserting these values into the IBU equations gives:
IBU(60) = 9.6 x .176 x 75 / 5 = 25 (rounded to nearest whole number) and
IBU(15) = 4.6 x .087 x 75 / 5 = 6
Giving a grand total of 31 IBUs.
"""""""""""""""""""""""""""""""
The main question I have is: How am I supposed to know what the boil gravity will be at minute 15, 30 or 60 or "X" when I am trying to design a beer?. If I am trying to design it from scratch (with no software help whatsoever) and want to figure out how bitter the beer will be, and find out the IBUs, how should I do it then?. If the IBUs calculation depends on the gravity of the boil, then it´s impossible to accurately (or at least a solid number) calculate the IBUs. Am I wrong?. I should be wrong, otherwise reaching a particular IBUs level would be erratic for every brewer.
Also, What is the boil gravity?. Is he meaning I need to measure the gravity of the wort while its at the 30 minute boiling time?.
Bottom line; I want to be able to set the amounts of malt (and kinds of malt), temperatures, and hops on paper. How can I calculate the IBUs (Utilization specifically) without waiting until boiling time?.