Ethanol Assisted Incorporation of Lutein into Whey Protein Stabilized Emulsions: how the Steps of Addition and Evaporation of the Solvent Affect the Obtained Systems

Lutein is a bioactive compound associated with several health benefits, but its incorporation into formulated products is challenging due to its low solubility. Lutein needs to be encapsulated in delivery systems such as emulsions or nanoparticles; however, low attention has been given to the effect the structure of the delivery system may have on its stability. Different emulsions were obtained using whey proteins as emulsifier, with comparable composition, but using different processing steps. Ethanolic lutein solution was added to the oil phase of the emulsion. The ethanol was then removed by evaporation before (O-L/W) or after (O + E-L/W) emulsification. Emulsions were also obtained using lutein loaded nanoparticles by desolvation, where the ethanol was evaporated before the emulsification step (O/W-L). There was a successful incorporation of lutein in the O-L/W and O + E-L/W emulsions, with encapsulation efficiencies higher than 95%. On the other hand, O/W-L emulsion had an encapsulation efficiency of 64%, with lutein distributed in the dispersed and continuous phases, as encapsulated in the protein nanoparticles. However, no differences could be noticed in the lutein degradation over 14 days of storage under a light source, between O-L/W and O/W-L samples, which ranged between 48 and 50%. But, it was more pronounced for O + E-L/W (close to 57%). O/W-L sample was the system most stable to creaming. The results highlight the importance of obtaining the right structures, by paying attention to the mode of incorporation of bioactive compounds, to improve the stability of the obtained systems.