Dogfish Head makes IPAs called "60 Minute", "90 Minute", and "120 Minute". According to Wikipedia:
Their names refer to the length of the boil time of the wort in which the hops are continuously added.
There is also a limited edition "75 Minute" which is really a blend of the 60 & 90 varieties.
What I find odd however, is that these numbers also roughly correspond to the beers' ABV% & IBU.
Again, from Wikipedia:
- 60 Minute: 6.0% ABV, 60 IBU
- 90 Minute: 9.0% ABV, 90 IBU
- 120 Minute: 18% ABV, 120 IBU
- 75 Minute: 7.5% ABV, (no IBU listed)
Generally, the ABV% is about one-tenth the boil time in minutes, while the IBU is directly equivalent. Is this naturally due to the chemical reactions which occur during this part of the brewing process, or must Dogfish Head be doing something in particular which leads to an abnormally tight correlation here?