Choline oleate based micellar system as a new approach for Luteolin formulation: Antioxidant, antimicrobial, and food preservation properties evaluation

Luteolin (LUT), an important flavonoid, shows excellent antioxidant and antimicrobial properties. However, its low solubility and stability in water, as well as challenges related to its formulation, have limited its use in food preservation. Here, we develop a highly water-soluble LUT-loaded micellar formulation (LUT-MF) using a solid-in-water nanodispersion technique involving emulsification and lyophilization processes. LUT solubilized in an organic phase comprising acetone, methanol, and cyclohexane (5:10:85 v/v) was emulsified with an aqueous solution of a surface-active ionic liquid, choline oleate ([Cho][Ole]), and the oil in water emulsion was lyophilized to remove the organic phase and water and obtain a solid LUT-[Cho][Ole] complex. LUT-[Cho][Ole] complex was dispersed again in water to prepare the LUT-MF formulation with good stability. Dynamic light scattering and transmission electron microscopy confirmed that the LUT-MF formed spherical micelles with a mean particle size of approximately 73 nm. LUT-MF showed excellent encapsulation efficiency (94.3%) and enhanced aqueous solubility. An in vitro release study in PBS containing 30% ethanol demonstrated 3.94 times higher release of LUT from LUT-MF than from LUT suspension after 24 h. The developed formulation showed better antioxidant activity than both free LUT and ascorbic acid. LUT-MF demonstrated higher antibacterial activity than sodium benzoate. Food preservation studies revealed that treating strawberries with LUT-MF effectively preserved color and prevented shriveling and decay over 8 days storage at 10 °C, compared with sodium benzoate treatment. The results suggest that LUT-MF is a potential natural preservative alternative to conventional toxic chemical preservatives used in the food industry.