Enhancing anthocyanin stability in blue honeysuckle berries via interaction with whey protein isolate: structural and...

Anthocyanins in blue honeysuckle berries, dominated by cyanidin-3-glucoside (C3G), are highly susceptible to degradation during processing, storage, and digestion, necessitating stabilization strategies. This study evaluated the effect of whey protein isolate (WPI) on anthocyanin stability and antioxidant capacity under illumination, thermal, storage, and in vitro digestion, and further examined the stabilization mechanisms. WPI at 0.10 mg mL^-1 provided the greatest protection across most conditions. After simulated digestion, the WPI-anthocyanin complex retained 7.48 ± 1.49 mg C3G g^-1, a 3.92-fold increase compared with the control. HPLC-ESI-QTOF-MS² showed that WPI effectively slowed the degradation of individual anthocyanin, especially C3G. Fluorescence and UV-vis spectroscopy indicated hydrophobic interactions as the dominant driving force, while FTIR revealed non-covalent binding induced structural changes in WPI. SEM/TEM further supported the formation of more compact and uniform complexes at optimal WPI levels. These findings demonstrate the potential of WPI to enhance anthocyanin stability in functional dairy applications.