Viability of Two Freeze‐dried Strains of Bifidobacterium and of Commercial Preparations at Various Temperatures During Prolonged Storage

Viability of bifidobacteria in freeze‐dried probiotic products at various temperatures during prolonged storage was assessed. Bifidobacterium longum 1941 and B. longum 536 were freeze‐dried and capsules were manufactured. Five commercial probiotic capsule products were also tested. The capsules were stored at ‐18 °C, 4 °C, and 20 °C. Cell counts were enumerated using MRS‐NNLP agar at 37 °C for 72 h under anaerobic conditions at 0, 1, 2, 5, and 8 mo (commercial capsules) and at 0, 1, 2, 5, 8, 11, 14, 17, and 20 mo (laboratory capsules). Storage at 20 °C showed the greatest decline in the viability of bifidobacteria, whereas that at ‐18 °C showed the least decrease.