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The wort is typically boiled with hops for 60 to 90 minutes in order to extract the bitter constituents (essentially alpha acids) from the hops. The alpha acids are antioxidants, but powerful hop polyphenol antioxidants are also extracted during this time. It is apparently best to boil for a shorter amount of time, such as 60 minutes. A hazy, polyphenol-rich beer is what is desired, and longer boil times may result in clearer beer. Longer boil times may facilitate the removal of proteins that exist in the wort. The proteins that contribute to haze adsorb (bind to) antioxidants, so should not be completely removed. A 90-minute boil should generally be fine, however, especially if dark malts are used. It may be best to add hops throughout the boil to extract different types of hop polyphenols. Hop polyphenols and other constituents such as the bitter alpha acids are isomerized, degraded, and lost during the boil (depending on the exact nature of the constituent). Isomerized and degraded hop constituents are still important antioxidants. In fact, the primary purpose of the boil is to isomerize the bitter alpha acids. Un-isomerized and undegraded hop constituents are also important antioxidants, and can be extracted and preserved when hops are added near or after the end of the boil.