Protection of Lactobacillus acidophilus from bile salts in a model intestinal juice by incorporation into the inner-water phase of a W/O/W emulsion

Lactic acid bacteria have been paid increasing attention as a probiotics, but their viability is affected by the various digestive processes of their host such as the acidic stomach solution and bile acids. The protection of Lactobacillus acidophilus JCM 1132 against the cytotoxic bile acids was examined by incorporating the bacteria in the inner-water phase of a W/O/W emulsion. Sodium glycodeoxycholate and sodium glycochenodeoxycholate (6 mmol/l each) significantly decreased the cell viability from 5.2×106 cfu/ml to 4.0×103 and 1.3×102 cfu/ml, respectively, when the bacteria were directly dispersed in the solutions at pH 7 for 2 h. However, their incorporation in the inner-water phase of the W/O/W emulsion improved the viabilities to 1.6×106 and 2.3×104 cfu/ml, respectively. This improvement was ascribed to the inclusion of the bacteria in the emulsion because the viability of the bacteria, which were dispersed with the emulsion containing no bacteria in the solution, was very low. Although sodium deoxycholate decreased the viability of the cells included in the W/O/W emulsion, the inclusion significantly improved the cell viability against primary and secondary bile acids.