Today in 1968, US Patent 3390000 A was issued, an invention of Robert J. Brison and John H. Litchfield, assigned to John I. Haas Inc., for their “Separation Of Lupulin From Hops.” There’s no Abstract, although in the description it includes this summary:

In the production of beer or ale one important ingredient employed is hops. Hops contain certain soft resins which impart not only bitterness to the beer, but also aroma. In the usual practice the hop cones which include the leaves, stems, petals, lupulin and at times, seeds, are boiled in their entirety within a sugary wort in order to extract the necessary resins and aromatic oils from the lupulin thereof. The lupulin particles are closed cup-like fibrous containers filled with hop flavoring substance including a relatively small amount of moisture, and essentially soft bitter resins and volatile aromatic oils.

It has been known however, that the flavor content of lupulin deteriorates in the ordinary practice of drying the hops prior to shipment to the brewery and that oxidation of lupulin occurs easily if the dried hops are not placed in sealed containers (preferably in an inert atmosphere) thus avoiding further oxidation thereof.

It will be recognized that such a procedure is costly since it involves packaging and handling extraneous -materials. Efforts dating back to the mid-nineteenth century have been directed to separating the lupulin from the hops although certain economic disadvantages have prevented their widespread acceptance. Further, many of these efforts result in a lupulin product excessively fragmented or crushed, thus exposing its valuable constituents to unnecessarily rapid and disadvantageous oxidation.

It is therefore an important object of the instant invention to overcome the disadvantages of prior art methods of separating lupulin from hops.

It is a further object of the instant invention to provide an improved method of separating lupulin particles from hops in the substantial absence of damage or comminution of said lupulin particles.

Another object of the instant invention is to provide an improved, simplified and economical method of separating lupulin particles from hops in the absence of appreciable particle size reduction and in the absence of appreciable oxidation or deterioration of the soft resin or volatile aromatic oil content `of said lupulin particles.

Still another object of the instant invention is to provide a simple, effective method of separating lupulin from hops which method can be implemented at the ranch or vine location and wherein the hops treated can be fresh (not dried, dehydrated or stored for any substantial length of time) or dried or a mixture thereof.

Today in 1975, US Patent 3891781 A was issued, an invention of Kurt Bauer, Helmut Findeiss, and Alfred Krempel, for their “Process For The Extraction Of Hops.” Here’s the Abstract:

Process for extracting from hops the essential brewing ingredients thereof, viz., neutral substances, bitter substances and tannin, which process comprises subjecting a primary extract solution of hops, e.g., in alcohol or hydrocarbon solvents, said solution containing as ingredients the neutral substances, bitter substances and tannin, to a first liquid-liquid extraction, wherein either (i) the tannins or (ii) the neutral substances are separated off, leaving a solution of (i) neutral and bitter substances or (ii) tannins and bitter substances, and subjecting the latter solution to a second liquid-liquid extraction to separate said solution into its components; the first extractant is desirably an aliphatic, cycloaliphatic or aromatic hydrocarbon when the primary extract solvent is an alcohol or aqueous-alcoholic solution, to result in extraction of the neutral and bitter substances in a hydrocarbon phase and leaving of the tannin in the alcoholic phase, whereafter the neutral and bitter substances are separated from each other by treating the extract with a second extractant, desirably aliphatic alcohol containing water.