Today in 1966, US Patent 3275447 A was issued, an invention of Adam Muller, for his “Process for the Preparation of Highly Concentrated Dry Hops by Freezing.” There’s no Abstract, although in the description it includes this summary:
The invention relates to a novel process for the preparation of a dry hops concentrate which contains substantially all of the lupulin components or bitter principles of the hops.
Hops concentrates have been prepared by organic solvent extraction methods and by dry methods. Dry methods of forming hops concentrates have not been completely successful since substantial losses of the bitter principles occur when discarding a portion of the strobile bracts which are the major component of raw hops. Known dry processes for forming hops concentrates high in lupulin values comprise separating the leaf and stem residues and the lupulin components by coarse flaking and screening of the hop strobiles or by fine comminution of the hops. However, complete recovery of the lupulin components has not been possible by these known dry methods and therefore only hop extracts produced by organic solvent extraction have gained commercial importance.
The process of the invention for the preparation of a hops concentrate which contains substantially all the lupulin values in the hops comprises freezing the hops wherein the lupulin forms distinct particles, comminuting the frozen hops to a particle size of 200 to 6000 microns whereby the lupulin particles are freed from the hops, separating the comminuted hops into a coarse fraction containing no lupulin and a fine fraction containing substantially all the lupulin in the hops and recovering the fine fraction.
The hops are frozen to a temperature of less than 10 0., preferably to a temperature of l5 to 30 C., although lower temperatures may be used. The said temperatures are necessary in order to form the lupulin particles which are often sintered together. into clumps. The deep-freezing may be effected in a freezing chamber or by evaporation of liquids having a low boiling point such as carbon dioxide, liquid nitrogen, etc.
By comminuting the hops to a particle size of 200 to 6000 microns, all of the lupulin glands, even those anchored in cone-like fashion in the leaf parenchyma of the strobile bracts, are separated from the hops in the form of individual beads so that a considerable savings in hops can be achieved during hopping of the wort due to the larger surface area of the bitter principle carriers.