Hydrophilic Carotenoids: Surface Properties and Aggregation of Crocin as a Biosurfactant

The surface and aggregation properties of the naturally occurring carotenoid crocin ( 1 ), examined through measurements of surface tension and UV/VIS absorption, have been used to determine the following parameters: critical aggregate concentration, surface‐saturation concentration, molecular area, free energy of adsorption and micellation, adsorption‐micellar energy relationship, equilibrium constants, and aggregate size. On structural grounds and based on the determined molecular area at the interface, the digentiobiosyl ester of the conjugated, highly unsaturated carotenoid diacid crocetin C20 : 7 should be classified as a bolaamphiphile. Crocin forms true monomolecular solutions in H₂O; only at rather high concentrations aggregation occurs.