Ethanol-assisted core-shell microparticles for enzyme stabilization with precise size control

In vegetarian diets, phytate is known to disrupt the adsorption of minerals. Fortifying foods with phytase, a therapeutic enzyme known to mitigate phytate, might increase the uptake of important nutrients. Phytase is susceptible to environmental stress such as heat and acidic conditions encountered during food processing. Therefore, we developed and optimized a core-shell microparticle composed of a phytase-chitosan core and a shell consisting of cross-linked alginate-κ-carrageenan. Ethanol was used to precipitate the microparticles, and the ethanol concentration was optimized along with the chitosan and phytase ratio and the alginate-carrageenan concentration, to form stable core-shell microparticles. The optimized core-shell microparticles have a loading capacity of 32.7% with a high encapsulation efficiency of 80.3% and uniform micro-size with a diameter of 3.2 µm and a poly-dispersity index of 0.178. Loaded phytase retained 62.7% enzymatic activity after heat treatment and digestion conditions. These results indicate that core-shell microparticles are suitable for retaining enzyme activity within the food matrix under typical food processing conditions.