Humulones

Portions of the alpha-acid family of hop bitters — the key bittering compounds in hops and beer. Boiling converts them into isohumulones, which give beer its characteristic bitterness. Hop varieties are graded and priced largely on their humulone (alpha-acid) content, making these compounds central to both hop commerce and beer quality. Brewers calculate hop additions from the alpha-acid percentage to hit target bitterness units, and storage conditions matter because alpha-acids degrade over time, steadily reducing a hop lot’s bittering power.