Alpha Acid Unit

alpha acid unit. (ael'-fuh ae'-sid yoo'-nit)

    A measurement of the potential bitterness of hops expressed in terms of their percentage of alpha acid content. Low equals 2–4 percent, medium equals 5–7 percent, high equals 8–12 percent. Abbrev: AAU. See also: bittering units; bitterness units; homebrewing bitterness units; hop bitterness coefficient; hop bitterness units.