I read somewhere that various desired hop oils have flash points (between 100-180 F, I think), so a brief chill down after FO to get the wort temp below 170-180 F was suggested before adding the steeping hops.
I've been doing Hop Stands between 140-170 F for approximately 20-30 minutes. I think it helps extract hop flavors and aromas, though the aromas are often lost/diluted by the CO2 outgassing during fermentation. Dry hopping is a good way to get back some of the aromas, but at the cost of grassy flavors and less clarity.
What do you think? Does the additional steeping time make a difference?
The only hop essential oil that has a flash point over 180F is Caryopholene (SP) at 200F, and this one has spicy charactor like black pepper. The others are about 78F to 112F, which is why you can get the big aroma from dry hopping, and that is why you want to dry hop at room temperature. When you rub hops between your hands, you are flashing off some of those oils due to your body temp and friction heat
I made a couple of beers with the last hop addition in the whirlpool for at least 40 minutes, after the wort had been cooled down to 100. I was expecting more aroma than I got.