This study compared the effect of different pH ofsimulated gastric juices on the viability of 13 dairypropionibacteria strains during 180-min simulatedgastric transit. There was no loss of viability for allstrains at pH 4.0; in contrast, at pH 3.0, 10 strainsretained the same level of viability, while at pH 2.0,all strains showed reduced viability (Table 1). Theseresults are comparable to the findings of Zarate et al.(2000), in which four dairy propionibacteria strainshave been shown to survive well at pH 4 and onestrain slightly lose viability at pH 3 but all tested fourstrains lose viability substantially at pH 2. The variability of dairy propionibacteria strains to survive atpH 2 and pH 3 suggests that the acid tolerance ofdairy propionibacteria is strain-specific, and pH values of 2 and 3 could be considered as critical for theselection of potential probiotic dairy propionibacteria.