Acetylation, which acts on the amino groups of proteins, allows to increase the solubility and the emulsifying properties of pea isolate. Acetylation by acetic anhydride was carried out in a torus microreactor in semibatch and continuous conditions. The mixing characteristics, obtained by a residence time distribution (RTD) method, are the same in batch and continuous processes. The maximum acetylation degree reached by the torus reactor is higher than with the stirred reactor. Torus reactors are more efficient than stirred ones as shown by a conversion efficiency, defined by the quantity of modified lysine groups by consumed acetic anhydride.