Electrostatic spray drying enhances transferrin hydrophilicity for improved rosmarinic acid binding: Insights into...

Different drying methods influence the hydrophilicity and surface charge of proteins, thereby modulating their binding affinity for polyphenols and functional properties. This study investigated the effects of electrostatic spray drying (ESD) on the structure and bioactivity of lactoferrin (LF) and ovotransferrin (OVT), as well as their interactions with rosmarinic acid (RA) across varying pH levels. ESD-transferrins demonstrated reduced contact angles and higher interfacial tension compared to spray-dried and freeze-dried proteins, indicating enhanced hydrophilicity. RA significantly enhanced the antioxidant capacity of transferrins at pH 3-5. The antibacterial efficacy of ESD-OVT/RA reached a peak of 90.25 % at pH 9. ESD-LF/RA exhibited potent antibacterial activity at pH 5 due to its strong positive charge (> 36 mV). Molecular docking analysis revealed pH-dependent binding modes, with hydrogen bonding predominant at pH 3-5 and hydrophobic interactions dominant under alkaline conditions. These findings highlight the potential of ESD in optimizing protein-polyphenol complexes for functional food applications.