The encapsulation β-carotene in whey protein concentrate (WPC) capsules through the emulsion electrospraying technique was studied, using deep eutectic solvents (DES) as solvents. These novel solvents are characterized by negligible volatility, a liquid state far below 0 °C, a broad range of polarity, high solubilization power strength for a wide range of compounds, especially poorly water-soluble compounds, high extraction ability, and high stabilization ability for some natural products. Four DES formulations were used, based on mixtures of choline chloride with water, propanediol, glucose, glycerol, or butanediol. β-Carotene was successfully encapsulated in a solubilized form within WPC capsules; as a DES formulation with choline chloride and butanediol, the formulation produced capsules with the highest carotenoid loading capacity. SEM micrographs demonstrated that round and smooth capsules with sizes around 2 µm were obtained. ATR-FTIR results showed the presence of DES in the WPC capsules, which indirectly anticipated the presence of β-carotene in the WPC capsules. Stability against photo-oxidation studies confirmed the expected presence of the bioactive and revealed that solubilized β-carotene loaded WPC capsules presented excellent photo-oxidation stability compared with free β-carotene. The capsules developed here clearly show the significant potential of the combination of DES and electrospraying for the encapsulation and stabilization of highly insoluble bioactive compounds.
Keywords: deep eutectic solvents; emulsion electrospraying; encapsulation.