**2.4. Physical characterization of the emulsion**

The particle size of the oil droplets in the lutein-enriched emulsions was measured at day 0 and day 7 after homogenization with a SALD-2101 laser diffraction particle analyzer (Shimadzu Corporation, Columbia, MD, USA). The charge of the oil droplets in the lutein-enriched emulsion (zeta potential, ζ, mV) was measured at day 0 with a Zetasizer nano ZS (Malvern Instruments, Worcestershire, UK). Samples were diluted 100 times in 5 mM phosphate buffer at pH 7.0. All measurements were carried out in triplicate at 21 ± 1°C.
