Influence of interfacial compositions on the microstructure, physiochemical stability, lipid digestion and β-carotene bioaccessibility of Pickering emulsions

Novel Pickering emulsions were co-stabilized by solid particles and two types of emulsifiers (lactoferrin or rhamnolipid) for delivery of beta-carotene. The influence of the particle-surfactant or particle-protein mixed interface on novel Pickering emulsions was investigated. The droplet size of the particles and lactoferrin co-stabilized Pickering emulsion was increased from 13.34 +/- 0.03 mu m to 20.70 +/- 0.09 mu m with the rise in lactoferrin level from 0.10% to 1.25% (w/v), but the droplet size of the particles and rhamnolipid co-stabilized Pickering emulsion was increased initially from 17.61 +/- 0.10 mu m to 38.24 +/- 0.11 mu m with the increase in rhamnolipid level from 0.10% to 0.75% (w/v) and then decreased to 15.17. 0.25 mu m at 1.25% of rhamnolipid. Compared to the emulsion stabilized by particles solely, the stability of Pickering emulsions co-stabilized by particles and emulsifiers, and the beta-carotene entrapment were improved under environmental stresses. Presence of lactoferrin or rhamnolipid might induce the competitive displacement, adsorption onto particle surface or multilayer deposition at the interface, which were observed through confocal laser scanning microscope and cryo-scanning electric microscopy. Furthermore, the addition of lactoferrin or rhamnolipid inhibited the release of free fatty acids from in vitro digestion effectively, thereby reducing the bioaccessibility of beta-carotene slightly. These findings facilitated to understand the effect of interfacial compositions on the stability and digestion fate of the nutraceutical emulsions co-stabilized by particles and protein or surfactant.