Effect of water activity on the stability of Lactobacillus paracasei capsules

- Viability of encapsulated probiotics decreases above water activity of 0.536.
- Thermodynamic compensation provides the critical water activity for the bacterial survival.
- The best bacterial stability was entropy driven.

Lactobacillus paracasei subsp. paracasei LBC81 microorganisms were encapsulated by fluidized bed drying using water-alginate system incorporating potato starch. The capsules were stored for seven weeks in aw (s) from 0.103 to 0.846 at 25, 35 and 45 °C. The quantitative analysis of microorganisms indicated that the survival of the strain decreased more rapidly over water activity of 0.536, which was considered as critical for maintaining these alive. This water activity can be obtained using the Rockland analysis. The enthalpy-entropy compensation revealed that encapsulated probiotics were kept alive when the adsorption process was controlled by entropy, which was where the critical water activity occurred.