Preparation of iso-alpha-acid-containing hop extracts

Claim 1

In the method for the preparation of an isomerized hop extract which consists essentially in extracting alpha-acids from hops with a solvent for alpha-acids to form an alpha-acid-containing hop extract, contacting a solution of said alpha-acids in a water immiscible, non-polar liquid with a base selected from the hydroxides and carbonates of sodium and potassium whereby said base and said alpha-acids react to form salts of the alpha-acids, heating said salts to effect isomerisation thereof, and transferring said isomerised salts, into an aqueous, alkaline phase, the improvement which consists in that a solution of the alpha-acids in a water immiscible non-polar liquid is contacted, prior to conversion into the salt form, with a sufficiently strong aqueous solution of acid to provide a pH of less than 1 in an aqueous phase that separates from said water-immiscible non-polar liquid after contacting said solution of alpha acids with said aqueous solution of acid.

Claim 19

A method for the preparation of isomerised hop extract which consists essentially in contacting a solution of an alpha-acid-containing hop extract in a non-polar, water-immiscible liquid having a boiling point greater than 100° C. with a sufficiently strong aqueous solution of acid to produce an aqueous phase after said contacting having a pH of less than 1, separating said aqueous phase from said liquid, contacting said liquid with a substantially anhydrous base selected from the group consisting of the hydroxides and carbonates of sodium and potassium to precipitate salts of the alpha-acids, heating said salts in said liquid at a temperature between 100° C. and 150° C., to form salts of iso-alpha-acids, contacting said salts of iso-alpha-acids with sufficient water to dissolve them at a pH between about 8 and 9.5, and separating an aqueous solution of iso-alpha-acid salts from said liquid.

Claim 20

A method for the preparation of isomerised hop extract which consists essentially in contacting a solution of an alpha-acid-containing hop extract in a non-polar, water-immiscible liquid having a boiling point greater than 100° C. with a sufficiently strong aqueous solution of acid to produce an aqueous phase after said contacting having a pH of less than 1, separating said aqueous phase from said liquid, contacting said liquid with a substantially anhydrous base selected from the group consisting of the hydroxides and carbonates of sodium and potassium to precipitate salts of the alpha-acids, heating said salts in said liquid at a temperature between 100° C. and 150° C., to form salts of iso-alpha-acids, contacting said salts of iso-alpha-acids with sufficient water to dissolve them at a pH between about 8 and 9.5, and separating an aqueous solution of iso-alpha-acid salts from said liquid.

Claim 21

A method for the preparation of isomerised hop extract which consists essentially in extracting hops with a volatile solvent for alpha acids, evaporating said solvent to form a hop extract containing alpha-acids, beta-acids and hop oils, dissolving said extract in a water-immiscible non-polar liquid contacting said extract in said liquid with a sufficiently strong aqueous solution of acid to produce an aqueous phase that separates from said liquid having a pH below 1, separating said aqueous phase from said non-polar liquid, contacting said liquid with sufficient substantially anhydrous potassium carbonate to form potassium salts of said alpha-acids, but not to form potassium salts of said beta-acids, heating said salts while in said non-polar liquid to isomerise said salts of said alpha-acids to form potassium salts of iso-alpha-acids, contacting said isomerised salts in said non-polar liquid with sufficient water to dissolve said salts of iso-alpha-acids at a pH insufficient to convert said beta-acids to the salt form, and in the presence of sufficient non-polar, water-immiscible liquid to retain said beta-acids in said non-polar liquid, and separating said liquid from an aqueous phase containing said iso-alpha-acid salts.

Claim 22

A method for the preparation of isomerised hop extract which consists essentially in extracting hops with a volatile solvent for alpha acids, evaporating said solvent to form a hop extract containing alpha-acids, beta-acids and hop oils, dissolving said extract in a water-immiscible non-polar liquid contacting said extract in said liquid with a sufficiently strong aqueous solution of acid to produce an aqueous phase that separates from said liquid having a pH below 1, separating said aqueous phase from said non-polar liquid, contacting said liquid with sufficient substantially anhydrous potassium carbonate to form potassium salts of said alpha-acids, but not to form potassium salts of said beta-acids, heating said salts while in said non-polar liquid to isomerise said salts of said alpha-acids to form potassium salts of iso-alpha-acids, contacting said isomerised salts in said non-polar liquid with sufficient water to dissolve said salts of iso-alpha-acids at a pH insufficient to convert said beta-acids to the salt form, and in the presence of sufficient non-polar, water-immiscible liquid to retain said beta-acids in said non-polar liquid, and separating said liquid from an aqueous phase containing said iso-alpha-acid salts.

Claim 24

A method according to either of claims 19 and 20 wherein said non-polar, water-immiscible solvent is hop oil contained by said extract.

Claim 26

A method for the production of isomerised hop extract which consists essentially in contacting a solution of hop extract containing alpha-acids in a non-polar, water-immiscible liquid with a sufficiently strong aqueous solution of acid to provide an aqueous phase having a pH of less than 1, separating said aqueous phase from said liquid, contacting said liquid with sufficient aqueous alkali to extract said alpha-acids from said liquid as their salts, separating said aqueous alkali containing said salts from said liquid and subsequently isomerising said alpha-acid salts.

Claim 27

A method for the production of isomerised hop extract which consists essentially in contacting a solution of hop extract containing alpha-acids in a non-polar, water-immiscible liquid with a sufficiently strong aqueous solution of acid to provide an aqueous phase having a pH of less than 1, separating said aqueous phase from said liquid, contacting said liquid with sufficient aqueous alkali to extract said alpha-acids from said liquid as their salts, separating said aqueous alkali containing said salts from said liquid and subsequently isomerising said alpha-acid salts.