Lutein is a hydrophobic carotenoid with various beneficial biological activities. Its use as a functional food, however, is currently limited by its low-water solubility, chemical instability, and poor bioavailability. The purpose of this work is to fabricate lutein-loaded nanoparticles to overcome these challenges. Lutein was encapsulated in zein nanoparticles coated with sophorolipid (ZSLNPs). The properties of ZSLNPs were characterized by transmission electron microscopy and dynamic light scattering. The results showed that the ZSLNPs were spheres with particle size around 200 nm and negative surface potentials (ζ = -54 mV). The encapsulation efficiency and loading capacity of the lutein in the ZSLNPs was 90.04% and 0.82%, respectively. Infrared spectroscopy analysis indicated that the dominant driving forces of the ZSLNPs formation mainly included electrostatic, hydrophobic interactions and hydrogen bonding. X-ray analysis showed that the encapsulated lutein was in an amorphous form. Circular dichroism analysis suggested that the incorporation of lutein or sophorolipid led to the change in secondary structure of zein. In addition, the ZSLNPs had good stability, redispersibility, and increased the water solubility of lutein. Furthermore, in vitro studies showed that the ZSLNPs had great biocompatibility and bioaccessibility of lutein. Overall, these findings indicated that the core/shell nanoparticles developed in the work may be suitable for encapsulating this important nutrient in functional foods.
Keywords: encapsulation; lutein; sophorolipid; zein nanoparticles.