The biological activity of polysaccharides used for nutraceuticals/drug excipients has been a neglected area of study. This work deals with the preparation, optimization, characterization, and evaluation of persimmon (Diospyros kaki Thunb.) fruit by-products and the study of the resultant dietary fiber (DF) interaction with other compounds, using acetaminophen as a model. Processing conditions for persimmon by-products were optimized to enhance antioxidant activity, with hypobaric, ultrasonic, and drying conditions tested at three levels of time and pH. The optimized DF was evaluated through in-vitro and ex-vivo release and permeation studies. Optimal conditions included three cycles of vacuum instantaneous expansion coupled with ultrasound waves (USEX), 42 min of ultrasound assisted extraction (UAE), and a pH of 1.5. After treatments, the antioxidant capacity (AC) increased six-fold, and zeta potential (ζ) analysis indicated polysaccharide aggregation at the optimized pH. The optimized polysaccharides, mainly formed by rhamnogalacturonan-I, displayed nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent activity. In-vitro drug-DF interaction studies showed higher acetaminophen release during digestion. Permeation kinetics adhered to the Korsmeyer-Peppas model in both ex-vivo and in-vitro models, suggesting complex permeation mechanisms. Results suggest that the optimized DF enhances the bioavailability and controlled release of acetaminophen, indicating its potential for use in drug delivery systems and nutraceutical applications.