The effect of different pH of simulated gastricjuices on viability of 13 dairy propionibacteria strainsis presented in Table 1. The average final pH of thesimulated transit mixture was 2.3, 3.8, and 6.0 for thepH 2.0, pH 3.0, and pH 4.0 gastric juices, respectively.In general, each strain showed lower viability insimulated gastric juice at pH 2.0 than in simulatedgastric juices with pH 3.0 or pH 4.0.When the simulated gastric juice was at pH 2.0, allthe strains showed progressive reduction in viabilityduring 180 min of simulated gastric transit, especiallyP. freudenreichii CSCC2200, P. freudenreichiiCSCC2206 and P. freudenreichii CSCC2216, whichlost total viability after 180 min of simulated gastrictransit.When the simulated gastric juice was at pH 3.0, 10out of 13 tested strains retained a similar level ofviability during simulated gastric tract transit for up to180 min. Only three strains, P. freudenreichii CSCC2206, P. acidopropionici 341, and P. acidopropionici ATCC25562, showed a 1-log reduction of viability after 180 min of simulated gastric tract transit.When the simulated gastric juice was at pH 4.0, allof the tested 13 strains retained the same level of viability during 180 min of simulated gastric tract transit.