The sensitivity of probiotics to lower pH in yogurt may be species and strain specific and this may be related to the observed higher viability of B. animalis subsp. lactis BB-12 compared to L. acidophilus LA-5 during storage. Unlike L. acidophilus, the effect of hydrogen peroxide on bifidobacteria has been reported to be minimal ( Dave and Shah, 1997a and Dave and Shah, 1997b).