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.