Add some Bitterness to your Brew
Bittering hops contribute no aroma and no flavor besides bitterness. The oils from the hop cone that produce the distinctive aromas and flavors are boiled away in ten to thirty minutes, depending on the variety of hops. The longer hops are boiled, the more bittering characteristics will come from those hops. Hops with high alpha acids (AA%) tend to work best as bittering hops.