A process for manufacturing an emulsion of alkenylsuccinic anhydride in an aqueous solution of cationic starchy material, comprising the steps of: a) preparing an aqueous solution of cationic starchy material, b) mixing the ASA and the aqueous solution of cationic starchy material obtained from step a), so as to obtain a cationic starchy material/ASA dry weight ratio of less than 1, c) preparing in a single pass in an emulsification unit an emulsion from the mixture obtained from step b), characterized in that: - the process does not involve recirculation of the emulsion obtained from step c) in the emulsification unit, and - in that the solids content of the aqueous solution of cationic starchy material obtained from step a) is between 5.5% and 11.5% and - characterized in that: said process is performed in a device consisting of: - a unit (a') for storing an aqueous solution of cationic starchy material to perform step a), - a unit (b') for mixing ASA and the aqueous solution of cationic starchy material, connected to the unit (a'), to perform step b), - a unit (c') for emulsifying the mixture of ASA and of the aqueous solution of cationic starchy material, connected to the unit (b'), to perform step c), said device not containing a recirculation loop in the emulsification unit (c'). a) preparing an aqueous solution of cationic starchy material, b) mixing the ASA and the aqueous solution of cationic starchy material obtained from step a), so as to obtain a cationic starchy material/ASA dry weight ratio of less than 1, c) preparing in a single pass in an emulsification unit an emulsion from the mixture obtained from step b), - the process does not involve recirculation of the emulsion obtained from step c) in the emulsification unit, and - in that the solids content of the aqueous solution of cationic starchy material obtained from step a) is between 5.5% and 11.5% and - characterized in that: said process is performed in a device consisting of: - a unit (a') for storing an aqueous solution of cationic starchy material to perform step a), - a unit (b') for mixing ASA and the aqueous solution of cationic starchy material, connected to the unit (a'), to perform step b), - a unit (c') for emulsifying the mixture of ASA and of the aqueous solution of cationic starchy material, connected to the unit (b'), to perform step c), said device not containing a recirculation loop in the emulsification unit (c'). said process is performed in a device consisting of: - a unit (a') for storing an aqueous solution of cationic starchy material to perform step a), - a unit (b') for mixing ASA and the aqueous solution of cationic starchy material, connected to the unit (a'), to perform step b), - a unit (c') for emulsifying the mixture of ASA and of the aqueous solution of cationic starchy material, - a unit (a') for storing an aqueous solution of cationic starchy material to perform step a), - a unit (b') for mixing ASA and the aqueous solution of cationic starchy material, connected to the unit (a'), to perform step b), - a unit (c') for emulsifying the mixture of ASA and of the aqueous solution of cationic starchy material, connected to the unit (b'), to perform step c), said device not containing a recirculation loop in the emulsification unit (c').