Hop addition question

[stutz]

I have a 90 minute IPA that gets a big addition at 90 and then a smaller addition at 45, then another big addition at flameout. My question is: Can I shorten the boil to 60 minutes and do a first wort addition? How much will this affect the hop character?

[mswebb]

Length of boil will be more dependant on the malts you use than the hop timing. We do a 90 minute boil for most of our beers and 60 for a few. We don't hop longer than 60 minutes in our 90 minute boil. For our 90 minute boil we are waiting for 30 minutes before first hops, in our 60 minute boil we add at first boil.

[UnFermentable]

I'm sure someone can point out the data, but if I recall Kunze book (or maybe one of the other great books) says you pretty much get maximum isomerization at 60 mins. Anything longer is not particularly beneficial and could cause more undesirable characteristics.