Abstract: A process for producing a biopolymer nanoparticles product is disclosed. In this process, biopolymer feedstock and a plasticizer are fed to a feed zone of an extruder having a screw configuration in which the feedstock is process using shear forces in the extruder, and a crosslinking agent is added to the extruder downstream of the feed zone. The biopolymer feedstock and plasticizer are preferably added separately to the feed zone. The screw configuration may include two or more steam seal sections. Shear forces in a first section of the extruder may be greater than shear forces in an adjacent second section of the extruder downstream of the first section. In a post reaction section located after a point in which the crosslinking reaction has been completed, water may be added to improve die performance.