Today in 1988, US Patent 4780330 A was issued, an invention of Derek R. J. Laws, assigned to The Brewing Research Foundation, for his “Method of Producing Isomerized Hop Preparations.” Here’s the Abstract:
A method for the production of isomerized hop preparations comprising admixing whole or powdered hops with a solid or aqueous alkali or alkaline earth metal salt. The invention provides that the resultant admixture is simultaneously subjected to a pressure of at least 2 Kg/cm2 and at a temperature of at least 80° C. in a closed vessel, thereby to form a hop preparation high in iso-α-acids and with substantially undegraded hop oils. The closed vessel is preferably an extrusion cooker.