Survivability and β-galactosidase activity of bifidobacteria stored at low temperatures

This work evaluated the ability of strains representing six species of Bifidobacterium with probiotic potential to survive and maintain beta-galactosidase activity through a two-step, low-temperature storage period. Cultures were also evaluated for their ability to ferment skim milk and retain viability during storage at 4 degrees C. Bifidobacterium longum ATCC 15707, B. breve 15700, and B, bifidum 29521 maintained the greatest viabilities at >1 x 10(7) CFU/mL, and B. infantis 15702 maintained the highest beta-galactosidase activity at >1 U/ml (with < 1 x 10(5) CFU/mL) after -60 to 4 degrees C storage. In fermented skim milk, B. breve 15700, B. bifidum 29521, and B. animalis 25527 tolerated a final product pH of 4.75 with > 1 x 10(8) CFU/mL remaining after 14 days of storage at 4 degrees C. Overall, it was found that highest levels of beta-galactosidase activities did not necessarily correlate to the highest plate-count populations.