Figure 4.

The protection principle of different embedding methods for microorganisms. (a) Microspheres/microcapsules mainly used colloidal materials with pH sensitivity to achieve multilayer embedding of microorganisms, and microcapsules disintegrated layer by layer to help microorganisms targeting release at the specific site in intestine. (b) Biopolymer microgels mainly protected microorganisms by adding colloidal antacids. Colloidal antacids maintained a neutral internal pH of biopolymer microgels under stomach conditions due to the ability of the hydroxyl ions for colloidal antacids to neutralize hydrogen ions arising from the gastric fluids. (c) Electrospraying made the emulsion dispersed into uniform and stable micron or nanometer droplets by high pressure and applied electric field.