Abstract:

Lactobacillus plantarum starter cultures were freeze-dried under vacuum, and the effect of water capacity on cell survival rate and viability of Lactobacillus plantarum during storage were studied. Results showed that there was no significant difference among the cell survival rates of Lactobacillus plantarum of different water capacity, but with the decrease of water capacity of Lactobacillus plantarum, the time of Lactobacillus plantarum logarithmic growth phase was postponed and the cell viability declined. The cell survival rate of Lactobacillus plantarum increased during storage under －20℃ and up to 91.46% on day of 515th, while the cell survival increased under 4℃ before 28d, and drop to 53.16% on day of 515th. In conclusion, the early stage of secondary drying phase was the ideal terminal point of freeze-drying. 4℃ was good for short time storage for Lactobacillus plantarum, while －20℃ was a better choice for longer time storage.

Key words: vacuum freeze-drying, Lactobacillus plantarum, water capacity, cell survival rate, viability