First Wort Hopping
An old yet recently rediscovered process (at least among homebrewers), first wort hopping (FWH) consists of adding a large portion of the finishing hops to the boil kettle as the wort is received from the lauter tun. As the boil tun fills with wort (which may take a half hour or longer), the hops steep in the hot wort and release their volatile oils and resins. The aromatic oils are normally insoluble and tend to evaporate to a large degree during the boil. By letting the hops steep in the wort prior to the boil, the oils have more time to oxidize to more soluble compounds and a greater percentage are retained during the boil.
Only low alpha finishing hops should be used for FWH, and the amount should be no less than 30% of the total amount of hops used in the boil. This FWH addition therefore should be taken from the hops intended for finishing additions. Because more hops are in the wort longer during the boil, the total bitterness of the beer in increased but not by a substantial amount due to being low in alpha acid. In fact, one study among professional brewers determined that the use of FWH resulted in a more refined hop aroma, a more uniform bitterness (i.e. no harsh tones), and a more harmonious beer overall compared to an identical beer produced without FWH.