Late Hops

[Hogarth]

Sorry if this has been answered elsewhere, but why do we add hops at five or ten or fifteen minutes before the end of the boil? If the bitterness comes from the first bunch of hops, and if the aromatic oils are best extracted from hops added after the boil (or even at 80°C) then what do these hops that are boiled for ten minutes contribute?

[mysterio]

Generally, flavour. Although they will contribute somewhat to aroma and bitterness too. However, the aroma hops at the end of the boil will contribute significantly to flavour too, just as you will pick up a little flavour from the bittering hops at the start of the boil.

[hoppingMad]

Discovering how the character of a beer can be manipulated through the use of late hopping is one of the real pleasures of brewing.
And you can be as subtle or as downright extravagant as you like when it comes to the amounts.
Hefty 10, 5 and zero minute additions followed by dry hopping an ounce or two in the right beer, once seemed crazy, until I tried it.
A world of flavour variations is waiting for you to try, not just with your malt choices but which hops to use, when and how much to add is why I enjoy homebrewing so much.
Oh and drinking the stuff is also quite nice too.