Crosslinking alginate at water-in-water Pickering emulsions interface to control the interface structure and enhance the stress resistance of the encapsulated probiotics

The strategies for stabilizing water-in-water (W/W) emulsions include the adsorption of solid particles at the water-water interface and the generation of interfacial films. We hypothesize that if sodium alginate is crosslinked at the water-water interface of W/W Pickering emulsions, the microstructure and rheological properties of the emulsions could be improved, thus enhancing the activity of encapsulated probiotics in simulated gastrointestinal digestion.The W/W Pickering emulsions comprised a dispersed maltodextrin (MD) phase in a continuous hydroxypropyl methylcellulose (HPMC) phase. The crosslinking W/W Pickering emulsion with fine-tuned internal structure was designed by leaching the CaCO3 particles packed in the dispersed phase to release Ca2+ crosslinked with sodium alginate.Confocal laser scanning microscope results revealed sodium alginate crosslinked with Ca2+ at the W/W interface. The rheological results of the crosslinking W/W Pickering emulsions suggested that the loss modulus (G″) was higher than the energy storage modulus (G'). The microstructure indicated that the emulsions formed a dense porous network structure after crosslinking conditions. The viable cell count of Lactobacillus helveticus CICC 22536 (LC) encapsulated in crosslinking W/W Pickering emulsion after simulated gastrointestinal digestion was 7.563 × 107 CFU/mL, which was three orders of magnitude higher than that of naked cells.