Patent GB-1064068-A (GB)
Title: Hop concentrate and process for preparation thereof
IPC: C07C49/743
Filed: 1963-12-10
Abstract: A hop concentrate is produced by extracting hops with a water-immiscible organic solvent, particularly trichloroethylene, extracting the organic extract solution so obtained with dilute aqueous alkali, separating the organic extract solution and aqueous extract solution into two phases, converting lupulones of the hop b -acids into hulupones by oxidizing the organic phase while isomerizing humulones of the a -acids into isohumulones by heating the separated aqueous phase, concentrating the organic phase containing hulupones by removal of solvent and concentrating the aqueous phase containing isohumulones by removal of water, and reserving both concentrates for subsequent addition to wort. Preferably, the organic extract solution is extracted with aqueous sodium carbonate (or hydroxide) solution, the sodium carbonate solution being sufficient to remove substantially all of the humulones in the organic extract solution; it is stated that some 10-20% of the lupulones also pass into the aqueous phase. The aqueous phase is boiled under an inert atmosphere to produce isohumulones, which are recovered as a heavy viscous oil by either concentration and chilling or acidification of the cold aqueous reaction product to pH 1-2, The lupulones in the organic phase, or raffinate. are converted to hulupones by oxidizing in an atmosphere of oxygen maintained at 1.5 lb. per sq. inch gauge pressure for 24 hours at ambient temperature.ALSO:A hop concentrate for use in a brewed beverage is produced by extracting hops with a water-immiscible organic solvent, particularly trichloroethylene, extracting the organic extract solution so obtained with dilute aqueous alkali, separating the organic extract solution and aqueous extract solution into two phases, converting lupulones of the hop b  - acids into hulupones by oxidizing the organic phase while isomerizing humulones of the a  - acids into isohumulones by heating the separated aqueous phase, concentrating the organic phase containing hulupones by removal of solvent and concentrating the aqueous phase containing isohumulones by removal of water, and reserving both concentrates for subsequent addition to wort.  Preferably, the organic extract solution is transferred to a mixing device and the alkali-soluble constituents are extracted several times with 0.5%-1.5% by weight aqueous sodium carbonate (or hydroxide) solution (1% with respect to the a  - acid), the total volume of the sodium carbonate solution being sufficient to remove substantially all of the humulones in the organic extract solution; it is stated that some 10-20% of the lupulones also pass into the aqueous phase. The aqueous phase is reacted by boiling for between 20 and 30 minutes under an inert atmosphere to produce isohumulones, which are recovered as a heavy viscous oil by either concentration and chilling to 5 DEG C. or acidification of the cold aqueous reaction product to pH 1-2.  The lupulones in the organic phase, or raffinate, are converted to hulupones by oxidizing in an atmosphere of oxygen maintained at 1.5 lbs. per sq. in. gauge pressure for 24 hours at ambient temperature. The raffinate is concentrated and the solvent removed by distillation at atmospheric pressure under a four-plate distillation column. The essential hop oils may be fractionated into 3 fractions of boiling points (i) 52-53 DEG C., (ii) 53-110 DEG C. and (iii) 110-140 DEG C., respectively, and a pot residue.  According to an example, 20% of fraction (i) and 25% of fraction (ii) were blended with 80% of fraction (iii), the blend being combined with the pot residue. The recovered isohumulones and the raffinate left after removal of hop oils and solvent, may be emulsified with the blend of hop oils and a quantity of sugar.