Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion.

Immunoglobulin Y (IgY) is an effective orally administered antibody used to protect against various intestinal pathogens, but which cannot tolerate the acidic gastric environment. In this study, IgY was microencapsulated by alginate (ALG) and coated with chitooligosaccharide (COS). A response surface methodology was used to optimize the formulation, and a simulated gastrointestinal (GI) digestion (SGID) system to evaluate the controlled release of microencapsulated IgY. The microcapsule formulation was optimized as an ALG concentration of 1.56% (15.6 g/L), COS level of 0.61% (6.1 g/L), and IgY/ALG ratio of 62.44% (mass ratio). The microcapsules prepared following this formulation had an encapsulation efficiency of 65.19%, a loading capacity of 33.75%, and an average particle size of 588.75 μm. Under this optimum formulation, the coating of COS provided a less porous and more continuous microstructure by filling the cracks on the surface, and thus the GI release rate of encapsulated IgY was significantly reduced. The release of encapsulated IgY during simulated gastric and intestinal digestion well fitted the zero-order and first-order kinetics functions, respectively. The microcapsule also allowed the IgY to retain 84.37% immune-activity after 4 h simulated GI digestion, significantly higher than that for unprotected IgY (5.33%). This approach could provide an efficient way to preserve IgY and improve its performance in the GI tract.