Formulation optimization of lecithin-enhanced pickering emulsions stabilized by chitosan nanoparticles for hesperidin encapsulation

Hesperidin is a flavonoid that exhibits reduced solubility in aqueous-based formulations. In the present study, hesperidin was encapsulated in food-grade oil-in-water (O/W) lecithin-enhanced Pickering emulsions that were stabilized by chitosan nanoparticles via a rotor-stator homogenizer. The objective of the experiment was to investigate the effects of formulation factors, i.e., chitosan nanoparticles (ChiNP), lecithin concentration, and the oil-to-water (O/W) ratio, on the physical stability of hesperidin-loaded emulsions. The mean droplet size (d(3,2)) and emulsion stability index (ESI) were predicted using the response surface methodology. The optimal formulation conditions were achieved when using concentrations of 1.1% (w/w) of ChiNP, 4.4% (w/w) of lecithin, and an O/W ratio of 0.24 (v/v), with a high ESI of 0.78 +/- 0.06, a d(3,2) of 2.5 +/- 0.87 mu m, and a polydispersity index (PDI) of 0.33. Therefore, the models explained 98% of the response variability. The emulsion characterizations, using confocal laser scanning microscopy (CLSM) micrographs, showed direct evidence that the ChiNP were adsorbed at the interface between the oil and water phases. Detailed microstructures of the emulsion droplets were visualized by Scanning Electron Microscopy (SEM), corroborating the potential of ChiNP as wall material for the development of Pickering emulsions. The shelf-life estimation of the hesperidin emulsions was characterized using an automated analytical centrifuge. The results inferred a long shelf-life for the emulsions since the obtained creaming velocity was lower. In conclusion, this versatile and straightforward approach can be potentially applied in the encapsulation of several oil-soluble active compounds for food applications. (C) 2017 Elsevier Ltd. All rights reserved.