Boil time

[hopfenundmalz]

@thomasbarnes

90-120 minute boil increases alpha acid extraction, which might be something to worry about if you’re trying to make an extremely bitter, high gravity beer or are have limited amounts of bittering hops. Otherwise, you can just compensate for the slightly lower utilization rate by using slightly more bittering hops or slightly higher alpha hops.

That is a true statement.  But you don’t get much more than a 60 minute boil.

For a 1.060 wort,Tinseth from Norm Pyle's Hops FAQ
Min       Utilization
60           .211
90           .226
120         .230

Around 90 minutes you start to break down more of the vegatative matter, and the Iso-AA can start to degrade into something that does not add to the bitterness.