This study evaluated the survival of Lactobacillus casei when immobilized onto montmorillonite (MMT) and
sodium exchanged montmorillonite (Na-MMT) under stress conditions. The results showed that adsorption of
L. casei onto MMT and Na-MMT surface reached equilibrium after 1.5 h. The percentages of L. casei adsorbed
onto the surfaces of MMT and Na-MMT at equilibrium were 55.3% and 83.7%, respectively. L. casei–mineral complexes
were characterized by X-ray diffraction, Fourier transformed infrared and thermogravimetric analysis, indicating
that L. casei cells were successfully immobilized onto MMT and Na-MMT. Characterization with scanning
electron microscope showed that cells attached well to the surface of clay minerals and numerous L. casei cells
were observed to form aggregates with clay mineral particles. Immobilization on MMT and Na-MMT protected
L. casei from simulated gastrointestinal conditions. Immobilization preserved the counts of L. casei higher than
107 CFU mL−1 throughout the storage at refrigerated conditions. Yogurts prepared with L. casei–mineral complex
presented lower values for post-acidification and higher stability compared to the product prepared with the addition
of L. casei in free status. The results of this study suggested the efficiency of immobilization by adsorption
onto clay minerals to increase the survival of L. casei in simulated gastrointestinal conditions, refrigerated storage
and yogurt.
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