LAUSR

Solid lipid nanoparticles (SLN) containing up to 37.5 wt% all-trans β-carotene in the lipid phase are potential water dispersible food colourants. SLNs have been made by hot-melt high-pressure homogenization with fully hydrogenated sunflower oil and with polysorbate 80 and sunflower lecithin as stabilizers. AFM revealed the SLNs had thin platelet structures most likely derived from the triglyceride crystal β-form as detected by X-ray diffraction. No indications of crystalline β-carotene were detected. HPLC analysis showed extensive isomerization of β-carotene into more than 10 cis-isomers, suggesting it is present as an amorphous mixture. The high β-carotene loadings did not affect the triglyceride crystal structure and the morphology of the SLNs. It is suggested the SLNs consist of a platelet core of crystalline triglyceride surrounded by an amorphous β-carotene containing layer. The layered structure is suggested to affect the colouring power of the SLNs at β-carotene-loadings above 15 wt% of the lipid phase.