Effects of different pre-freezing temperatures on the freeze-drying survival rate and stability during room temperature storage of Lactiplantibacillus plantarum LIP-1

We determined the effects of different pre-freezing temperatures (−20 °C and −80 °C) on the freeze-drying survival rate and stability during room temperature storage of Lactiplantibacillus plantarum LIP-1. The underlying mechanisms of survival and stability were also assessed. The freeze-drying survival rate and stability during room temperature storage of Lactiplantibacillus plantarum LIP-1 was significantly higher in the −80 °C than −20 °C group ( p < 0.05). Regarding the underlying mechanism, compared with the −20 °C group, the −80 °C group had a lower level of intracellular reactive oxygen species, lower degree of oxidation of fatty acids in the cell membrane, high integrity and fluidity of the cell membrane during freeze-drying and room temperature storage, and a significantly higher freeze-drying survival rate and storage stability ( p < 0.05). This study provides reference data that could help improve the freeze-drying survival rate and stability of probiotics during room temperature storage.