Application of Natural Polymers to Enhance Probiotic Stability Following the Spray Freeze Drying Method

Probiotics, defined as live microorganisms that confer health benefits on the host, are sensitive to environmental stresses. However, the stability of Lactobacillus casei during spray freeze drying (SFD) under different encapsulation conditions has not been thoroughly investigated. In various concentrations, the influence of three natural polymers, sodium alginate, xanthan gum, and chitosan, is evaluated on the stability and physicochemical properties of SFD-processed Lactobacillus casei powder at different storage temperatures, 4 °C, 25 °C, and 40 °C, for 90 days, as well as probiotic stability in simulated gastric and bile-containing media. In addition, the particles' physicochemical properties are evaluated by tap density, FTIR, SEM, and DSC analysis. Probiotic microparticles after SFD are composed of a highly porous amorphous phase of polymers and various polymorphous structures of sucrose. Data shows that bacterial viability exceeds 90% immediately after SFD when low sodium alginate or xanthan gum concentrations were used. In addition, chitosan negatively impacts probiotic viability. However, applying a higher polymer ratio is problematic in long-term storage and contact with gastric fluid.