Effect of glutathione on Lactiplantibacillus plantarum stability during room temperature storage and the underlying mechanism of action

Previous studies have found that the decreased activity of probiotics during long-term storage is one of the main reasons leading to the decline of probiotics function. To improve the stability of probiotics during storage at room temperature, this study observed the effect of glutathione (GSH) addition to the culture medium on the storage stability of four Lactiplantibacillus plantarum strains. The results showed that the absorption of GSH by L. plantarum was strain-specific; Strain with GSH absorption capacity had significantly improved room temperature storage stability (P < 0.05). The mechanism of action was also determined. The main reason for the death of the strain during storage was the loss of integrity caused by the oxidation of unsaturated fatty acids on the cell membrane, after the consumption of GSH by a strain, the scavenging rates of 1, 1-diphenyl-2-nitrophenylhydrazine free radical (DPPH) and hydroxyl free radical, as well as their total reducing ability, were significantly increased (P < 0.05). Reactive oxygen species (ROS) were effectively eliminated after absorption of GSH by a particular strain during storage (P < 0.05), which reduced the oxidation of unsaturated fatty acids on cell membrane, the ratio of unsaturated fatty acids to saturated fatty acids (U/S) in the cell membrane was maintained, which reduced cell membrane damage and improved storage stability at room temperature. These findings provide a theoretical reference for improving strain storage stability at room temperature by adjusting the composition of the culture medium.