Supramolecular solvents as transfer vectors of carotenoids from carrot peels to nanostructured lipid carriers

Natural carotenoids are in increasingly high demand, but the high cost, low efficiency, and poor sustainability of current extraction processes limit their production. In this paper, a supramolecular solvent (SUPRAS), obtained by the water-induced coacervation of octanoic acid, was proposed for the extraction of the major (α- and β-carotene) and minor (lycopene and lutein) carotenoids present in carrot peels. Then, the carotenoid-loaded SUPRAS extracts were subsequently used for carotenoids encapsulation in nanostructured lipid carriers (NLCs). Extraction efficiencies for the four carotenoids were in the range 96–100 % for sample:SUPRAS ratio of 1:2.25 g:mL. The extraction process involved only stirring the sample-SUPRAS mixture for 10 min at room temperature. Both the large number of binding sites available in the inverted hexagonal aggregates of the SUPRAS and the perfect accommodation of the carotenoids in these nanostructures accounted for the high extraction efficiencies obtained. The carotenoid-loaded SUPRAS-NLCs particles were spherical with a size of 157 ± 1 nm. Their encapsulation efficiency for the four carotenoids was in the interval 67–81 %, and their antioxidant capacity was 4.4 ± 0.6 Trolox equivalents. SUPRAS extraction was evaluated using the Red-Green-Blue model, achieving high scores in performance, green chemistry, and practicality, resulting in an overall White rating.