Abstract: In this study, the effects of matrix structures on the crystal thermodynamic properties and solidified layer thickness of lutein-loaded nanostructured lipid carriers as well as lipid digestibility, lutein release, micelle formation and lutein bioaccessibility in Lutein-NLCs were investigated. The results showed that as the concentration of linseed oil increased, the melting point and enthalpy value of Lutein-NLCs first increased and then decreased, and the thickness of the solidified layer gradually decreased. The degree of lipid hydrolysis, the release of free fatty acids (FFAs) and monoacylglycerols (MAGs), and the bioaccessibility of lutein gradually decreased with increasing concentration of linseed oil up to 90%. The rate and extent of hydrolysis of MAGs and FFAs in Lutein-NLCs with four different matrix structures were positively correlated with their rate and extent of micellization. The release rate of lutein from Lutein-NLCs with linseed oil concentration higher than 10% was negatively correlated with the hydrolysis rate of TAGs. The micellization rate of lutein was negatively correlated with those of MAGs and FFAs, and was positively correlated with lutein release rate. The bioaccessibility of lutein was positively correlated with its release degree.

Key words: lutein; nanostructured lipid carriers; matrix structures; release properties; bioavailability