Abstract: A process for the stabilization and isomerization of .alpha.-acids in hops by comminuting and treating hops with calcium or magnesium oxide or hydroxide to form the metal salts and subjecting them to an elevated temperature while isomerization to iso-.alpha.-acids occurs, is characterized in that the mixture of hops and calcium or magnesium oxide or hydroxide is formed into pellets under conditions controlled to minimize isomerization. The pellets are packed in the absence of oxygen and the sealed packs are subjected to controlled heating at about 40.degree. to 55.degree. C. for a period of at least one day, the time, temperature and calcium or magnesium oxide or hydroxide content being selected so as to effect substantially complete isomerization.