This study explores the effect of ultrasound-assisted cellulase (UE) processing on the structure, functional performance, and prebiotic properties of guava insoluble dietary fiber (RIDF). As the ultrasound exposure time increased (0-40 min), the particle size (from 126.3 mu m to 38.7 mu m) and crystallinity (from 30.72% to 14.42%) of RIDF significantly decreased, while its soluble carbohydrate content (from 1.40% to 6.17%) and water solubility (from 8.6% to 16.4%) notably increased. These crucial changes suggested the degradation and disorganization of RIDF. Meanwhile, UE-RIDF (modified RIDF) ...