Rapid Adsorption of Naringin from Citrus Juice by β-Cyclodextrin Polymer

A β-cyclodextrin (β-CD) polymer crosslinked with tetrafluoroterephthalonitrile (1:2 molar ratio) was developed for the rapid removal of naringin, the primary bitter compound in citrus juice. The polymer achieved adsorption equilibrium within 120 s—dramatically faster than most reported naringin adsorbents—with a maximum adsorption capacity of 24.74 mg/g (Langmuir model). Kinetic data were well described by the Pseudo-second-order and Elovich models, indicating a heterogeneous, multi-site adsorption process. Isotherm analysis confirmed the coexistence of monolayer coverage and site heterogeneity (Toth model, adjR2 > 0.99). Under optimized conditions (adsorbent 300 mg/L, initial naringin 15 mg/L, pH 3.5), the polymer achieved an adsorption capacity of 18.84 mg/g in grapefruit juice. The adsorbed naringin was effectively eluted with 80% ethanol, and the polymer retained its original adsorption efficiency over seven consecutive cycles. Mechanistic studies (XPS, FTIR, molecular docking, and gradient elution) revealed synergistic contributions from π–π stacking, hydrogen bonding, and hydrophobic interactions. The combination of ultra-fast kinetics, good regenerability, and multi-mechanism binding makes this β-CD polymer a promising candidate for practical debittering of citrus juices in food processing applications.