Effect of encapsulation by emulsion method on survival of Lactobacillus reuteri in simulated gastric conditions

The health benefits of probiotic bacteria have led to an increase in their use in food products. The low stability of probiotic bacteria against adverse environmental conditions and the consequent reduction of survival during processing, storage period and also during consumption, is the most important limitation in the production and development of probiotic products. Encapsulation of probiotic bacteria is one of the technologies that has been successfully implemented in numerous studies to increase the stability of bacteria against environmental stresses. The aim of this study was to evaluate the core-shell encapsulation technology using calcium alginate, xanthan and gelan wall materials on the survival of Lactobacillus reuteri in simulated gastric conditions (pH = 1.5) by emulsion method.

Lactobacillus reuteri (ATCC 1655) was encapsulated with calcium alginate, xanthan and gelan by emulsion method and survival of encapsulated and free bacteria in simulated gastric conditions at intervals of zero, 30, 60, 90 and 120 minutes at temperature 37°C were evaluated. Also, the morphology and size of the microcapsules were determined by SEM electron microscope and particle size analyzer.

The morphology of the microcapsules obtained from the under study wall materials was spherical to oval. The average diameter of microcapsules in all wall materials under study showed a significant difference (p≤0.05). The average diameter of the microcapsules was affected by the wall materials under study and it has been shown that the simultaneous use of alginate, xanthan and gelan as wall materials, in addition to strengthening the microcapsules, leads to an increase in the diameter of the microcapsules. The encapsulation efficiency in all the wall materials under study was more than 90%, which indicates the suitability of the emulsion method in the encapsulation of Lactobacillus reuteri. The highest encapsulation efficiencies were related to (alginate) and (alginate and gellan) treatments which showed a significant difference (p≤0.05) compared to other wall materials. The lowest encapsulation efficiency among the wall materials under study was related to the treatment (alginate, xanthan and gelan). The highest and lowest survival rates in simulated gastric conditions among the wall materials under study were related to wall materials (alginate, xanthan and gelan) and (alginate alone), respectively, which show a significant difference (p≤0.05) with other wall materials.

Encapsulation of Lactobacillus reuteri by emulsion method with wall materials (alginate, xanthan and gelan) in addition to significantly improving survival in simulated gastric conditions, it increases the average diameter of microcapsules and also reduces the encapsulation efficiency.