Curcumin-based residue-free and reusable photodynamic inactivation system for liquid foods and its application in freshly squeezed orange juice

To enhance curcumin's application in photodynamic inactivation (PDI) of liquid foods, a supramolecular complex of biotin-modified β-cyclodextrin and curcumin (Biotin-CD@Cur) was synthesized. This complex significantly improves curcumin's solubility, stability, and PDI efficiency. Following PDI, Biotin-CD@Cur can be magnetically separated from the liquid matrix using streptavidin-coated magnetic beads (SA-MBs). Leveraging the reversible binding between streptavidin and biotin, Biotin-CD@Cur and SA-MBs fully dissociate in ultrapure water at 70 °C, enabling reuse. Antibacterial tests in freshly squeezed orange juice demonstrated that a low dose of 1.5 J/cm 2 from a 420 nm LED array and 10 μg/mL of Biotin-CD@Cur achieved log reductions of 3.287 ± 0.015 for Staphylococcus aureus and 2.961 ± 0.011 for Listeria monocytogenes , while preserving the juice's flavor and nutritional contents. The PDI system remained effective for at least four cycles. Ultra-performance liquid chromatography and atomic absorption spectroscopy confirmed no residues of system components in the juice after magnetic separation.