Patent GB-1058975-A (GB)
Title: Method of treating hops
IPC: C12C3/04
Filed: 1963-08-06
Abstract: Hops are treated with a water-immiscible co-solvent for a -acids and b -acids (a -acids comprising a mixture of humulone, co-humulone and ad-humulone, and b -acids comprising principally lupulone), particularly hexane, toluene or chloroform, a solvent extract containing the a -acids and b -acids is separated from the treated hops, the solvent extract is treated with a substantially stoichiometric amount, based on the estimated amount of a -acids in the extract, of an aqueous alkali metal hydroxide solution, particularly sodium or potassium hydroxide, and the resultant aqueous layer, which contains the a -acids in salt form substantially free of b -acid salts, is separated from the solvent layer, which contains the b -acids. The a -acid salts may be freeze-dried to powder form or neutralized to give a thick oil of free a -acids.  If the extraction with the queous alkali metal hydroxide solution is conducted at temperatures of 60 DEG  C. and above, mixtures of a -acid salts and iso salts or of free a -acids and isohumulone (as the case may be) will be obtained.  The solvent layer containing the b -acids is treated with a stoichiometric amount of aqueous alkali metal hydroxide solution to form a second aqueous layer containing the b -acids in salt form and a solvent layer, and the second aqueous layer is separated from the solvent layer.  The b -acid salts may be freezedried to powder form or neutralized to give a thick oil of free b -acids.  The remaining solvent layer is distilled to recover a hop oil extract. For the extraction treatment dried whole or ground hops, green hops, frozen hops and dried or fresh lupulin may be employed.ALSO:Hops are treated with a water-immiscible co-solvent for a -acids and b -acids, particularly hexane, toluene and chloroform (also naphtha), a solvent extract containin the a -acids and b -acids is separated from the treated hops, the solvent extract is treated with a substantially stoichiometric amount, based on the estimated amount of a -acids in the extract, of an aqueous alkali metal hydroxide solution, particularly sodium or potassium hydroxide, and the resultant aqueous layer, which contains the a -acids in salt form substantially free of b -acid salts, is separated from the solvent layer, which contains the b -acids. The a -acid salts may be freeze-dried to powder form or neutralized to given a thick oil of free a -acids.  If the solvent extraction with the aqueous alkali metal hydroxide solution is conducted at temperatures of 60  DEG C. and above, mixtures of a -acid salts and iso salts or of free a -acids and isohumulone (as the case may be) will be obtained.  The solvent layer containing the b -acids is treated with a stoichiometric amount of aqueous alkali metal hydroxide solution to form a second aqueous layer containing the b -acids in salt form and a solvent layer, and the second aqueous layer is separated from the solvent layer.  The b -acid salts may be freeze-dried to powder form or neutralized to give a thick oil of free b -acids.  The remaining solvent layer is distilled to recover a hop oil extract.  The hop residue from the initial solvent extraction step is treated with hot water to recover water-soluble tannins.  For the extraction treatments dried whole or ground hops, green hops, frozen hops and dried or fresh lupulin may be employed. The free a -acids and b -acids may be encapsulated with malto-dextrin or absorbed on inert materials. The a -acids, b -acids, hop oil extract and water-soluble tannins may be utilized in the brewing of malt beverages.ALSO:Hop oils obtained in the extraction of a -acids and b -acids from hops may be added to perfumes to impart thereto an aromatic aroma.