Electrosprayed Ethyl Cellulose Core-Shell Microcapsules for the Encapsulation of Probiotics

Electrosprayed ethyl cellulose core–shell microcapsules were produced for the encapsulation of probiotic Bifidobacterium animalis subsp. lactis (Bifido). Ethyl cellulose (ETC) was used as a shell material with different core compounds (concentrated Bifido, Bifido–maltodextrin and Bifido–glycerol). The core–shell microcapsules have an average diameter between 3 µm and 15 µm depending on the core compounds, with a distinct interface that separates the core and the shell structure. The ETC microcapsules displayed relatively low water activity (aw below 0.20) and relatively high values of viable cells (109–1011 CFU/g), as counted post-encapsulation. The effect of different core compounds on the stability of probiotics cells over time was also investigated. After four weeks at 30 °C and 40% RH the electrospray encapsulated samples containing Bifido–glycerol in the core showed a loss in viable cells of no more than 3 log loss CFU/g, while the non-encapsulated Bifido lost about 7.57 log CFU/g. Overall, these results suggest that the viability of the Bifido probiotics encapsulated within the core–shell ETC electrosprayed capsules can be extended, despite the fact that the shell matrix was prepared using solvents that typically substantially reduce their viability.