Patent GB-1082725-A (GB)
Title: Method of obtaining flavouring ingredients from hops
Inventor: WOLTON DAVID ALEXANDER
Filed: 1963-06-13
Abstract: Hops, or a hop-resin containing fraction derived from hops, is subjected to solvent extraction using an organic solvent which is substantially immiscible with water, the organic extract is partitioned with an aqueous alkaline solution and the aqueous phase is separated from the organic phase.  Suitable organic solvents are normally liquid hydrocarbons including pentane and its higher homologues; petroleum spirit of boiling point between 40 DEG  and 100 DEG C; benzene, toluene and other normally liquid homologues of benzene; ethers such as diethyl, di-isopropyl and dibutyl ethers; and carbon tetrachloride, chloroform, tri-, tetra-, and perchloroethylene, hexachloroethane and methylene chloride.  Suitable alkaline solutions include solutions of alkali metal hydroxides, carbonates and bicarbonates, and alkaline earth hydroxides.  The organic fraction remaining after the separation can be recycled to the extraction and after it has been so used a number of times, is steam distilled to isolate hop oils from the distillate.  The hop resins extracted may be treated with hot, i.e. at between 70 DEG  and 130 DEG C., alkaline solution in the absence of oxygen and under pressure, if necessary, whereby humulones are isomerized to isohumulones; the concentration of the alkali should not exceed 6.5% in the case of caustic alkali or 3% for alkali metal carbonate, so as to avoid degradation to humulinic acid. Thus, if a more concentrated alkali has been used for the partition, it must be diluted, partially neutralized by addition of acid, or converted into the corresponding carbonate by passing carbon dioxide through the solution.  At some stage before the hop resins are dried, a protective colloid such as methyl cellulose, alginates, alginic acid and beer "finings", may be added to prevent agglomeration. Especially when no protective colloid is present, the acidification may be carried out in the presence of a carrier such as diatomaceous earth or silica gel, in proportions ranging between 5 and 200% of the weight of the hop resins, on which the resins precipitate.  A preferred hop fraction for the extraction is a lupulin-rich material obtained by mechanically disintegrating hops or hop waste and removing the coarse particles by screening through openings at most 0.3 mm across. According to an example, 20 parts of hops are stirred with 320 parts of petroleum spirit (60 DEG -80 DEG C. fraction) for from 5 to 10 minutes and the mixture is then filtered.  50 parts of 5% caustic soda solution are added to the filtrate and the resultant mixture is vigorously agitated for 2 minutes and allowed to separate for 10 minutes. The alkali is run off and 2 parts of diatomaceous earth is added.  The solution is acidified to pH 2-3 with 10% hydrochloric acid while stirring, causing the resins to precipitate on the carrier. The precipitate is allowed to settle, or is separated by centrifuging, after which it is washed with water and dried to a powder.  The partition with alkali may be effected continuously in counterflow within a packed column. In a further example, an alkaline solution of hop resins obtained by a similar procedure employing trichloroethylene and de-oxygenated caustic soda solution, is diluted to a caustic soda concentration of 0.3% and is then boiled under atmospheric pressure for 45 minutes to isomerize the humulones to isohumulones. The boiled liquid is acidified quickly to pH 3 with hydrochloric acid and about 0.2% methyl cellulose is added.  The resulting precipitate is allowed to settle, is washed with water and is adjusted to pH 6.5-7.5, the same amount of methyl cellulose is added again and the precipitate is dried to a powder in the absence of oxygen by either a vacuum or freeze drying.  Yet a further Example is directed to the extraction of lupulin.ALSO:Hops, or a hop-resin containing fraction derived from hops, is subjected to solvent extraction using an organic solvent which is substantially immiscible with water, the organic extract is partitioned with an aqueous alkaline solution, and the aqueous phase is separated from the organic phase.  Suitable organic solvents are normally liquid hydrocarbons including pentane and its higher homologues; petroleum spirit of boiling point between 40 DEG  and 100 DEG C; benzene, toluene and other normally liquid homologues of benzene; ethers such as diethyl, di-isopropyl and dibutyl ethers; and carbon tetrachloride, chloroform, tri-, tetra-, and perchloroethylene, hexachloroethane and methylene chloride.  Suitable alkaline solutions include solutions of alkali metal hydroxides, carbonates and bicarbonates, and alkaline earth hydroxides.  The organic fraction remaining after the separation can be recycled to the extraction and after it has been so used a number of times, is steam distilled to isolate hop oils from the distillate.  The hop resins extracted may be treated with hot, i.e. at between 70 DEG  and 130 DEG C., alkaline solution in the absence of oxygen and under pressure, if necessary, whereby humulones are isomerized to isohumulones; the concentration of the alkali should not exceed 6.5% in the case of caustic alkali or 3% for alkali metal carbonate, so as to avoid degradation to humulinic acid. Thus, if a more concentrated alkali has been used for the partition, it must be diluted, partially neutralized by addition of acid, or converted into the corresponding carbonate by passing carbon dioxide through the solution.  At some stage before the hop resins are dried, a protective colloid such as methyl cellulose, alginates, alginic acid and beer "finings", may be added to prevent agglomeration.  Especially when no protective colloid is present, the acidification may be carried out in the presence of a carrier such a diatomaceous earth or silica gel, in proportions ranging between 5 and 200% of the weight of the hop resins, on which the resins precipitate.  A preferred hop fraction for the extraction is a lupulin-rich material obtained by mechanically disintegrating hops or hop waste and removing the coarse particles by screening through openings at most 0.3 mm across. According to an Example, 20 parts of hops are stirred with 320 parts of petroleum spirit (60 DEG -80 DEG C. fraction) for from 5 to 10 minutes and the mixture is then filtered.  50 parts of 5% caustic soda solution are added to the filtrate and the resultant mixture is vigorously agitated for 2 minutes and allowed to separate for 10 minutes.  The alkali is run off and 2 parts of diatomaceous earth is added.  The solution is acidified to pH 2-3 with 10% hydrochloric acid while stirring, causing the resins to precipitate on the carrier.  The precipitate is allowed to settle, or is separated by centrifuging, after which it is washed with water and dried to a powder.  The partition with alkali may be effected continuously in counterflow within a packed column.  In a further Example, an alkaline solution of hop resins obtained by a similar procedure employing trichloroethylene and de-oxygenated caustic soda solution, is diluted to a caustic soda concentration of 0.3% and is then boiled under atmospheric pressure for 45 minutes to isomerize the humulones to isohumulones.  The boiled liquid is acidified quickly to pH3 with hydrochloric acid and about 0.2% methyl cellulose is added.  The resulting precipitate is allowed to settle, is washed with water and is adjusted to pH 6.5-7.5, the same amount of methyl cellulose is added again and the precipitate is dried to a powder in the absence of oxygen by either a vacuum or freeze drying.  Yet a further Example is directed to the extraction of lupulin.