Enriched Z-isomers of lycopene-loaded nanostructured lipid carriers: Physicochemical characterization and in vitro bioaccessibility assessment using a diffusion model

The water solubility, stability and bioaccessibility of lycopene were improved with lycopene-loaded nanostructured lipid carrier (lyco-NLC). The average size of the lyco-NLC was about 230 nm with a small size distribution (PDI < 0.3). The encapsulation efficiency of lycopene was proved to be 92.73% and the content of total lycopene in the product was up to 3 mg/mL. The ratio of total Z-lycopenes in lyco-NLC was higher up to 50%. Particles of the lyco-NLC were found to be spherical and uniform in shape under AFM. FTIR and XRD showed that lycopene with high-ratio of Z-isomers was well incorporated into NLC. Stability of the lyco-NLC, as analyzed at -18 degrees C, 4 degrees C, 20 degrees C and 37 degrees C for 30 days, showed the particle size, PDI, retention rate of lycopene and the ratio of total Z-lycopenes were stable at 4 degrees C. The release behavior showed a relatively fast release during the first stage followed by a sustained release during the subsequent time. The partition factor (PF) values of both lyco-NLC and Z-lycopenes (50%) were 45%, which were two times of that of all-E-lycopene, indicating that the high proportion of Z-lycopenes could efficiently improve the bioaccessibility of lyco-NLC product.