The Effect of a Glutathione (GSH)-Containing Cryo-Protectant on the Viability of Probiotic Cells Using a Freeze-Drying Process

Lactic acid bacteria (LAB) and probiotics promise specific health benefits to their host. However, good storage stability is a prerequisite for their functioning and industrial use. This study aimed to evaluate glutathione (GSH) as a potential protective agent for improving microbial stability deteriorated by freeze-drying, freeze-thawing, and cold treatments. In this study, the optimal concentration of glutathione (50% w/w) was 1%, showing effective protection on the viability and stability of various LAB strains (Lactiplantibacillus plantarum MG4229 and MG4296, Lactococcus lactis MG5125, Limosilactobacillus fermentum MG4295, Lacticaseibacillus paracasei MG5012, and Bifidobacterium animalis ssp. lactis MG741). Glutathione-containing protectants considerably improved the viability of all of these strains after freeze-drying compared with non-coated probiotics. Survivability in the gastrointestinal (GI) tract, accelerated stability tests, and adhesion assays on intestinal epithelial cells were performed to determine whether glutathione enhances bacterial stability. Based on morphological observations, protectants containing GSH were coated onto the cell surface, resulting in effective protection against multiple external stress stimuli. The applicability of GSH as a new and effective protective agent can improve the stability and viability of various probiotics with anti-freezing and anti-thawing effects.

Automated summary

This study found that glutathione (GSH) can be a potential protective agent for improving the stability of lactic acid bacteria (LAB) and probiotics under freeze-drying, freeze-thawing, and cold treatments. The optimal concentration of GSH (50% w/w) showed effective protection on the viability and stability of various LAB strains. GSH-containing protectants enhanced the survivability of probiotics after freeze-drying and showed anti-freezing and anti-thawing effects.