Smart drying of probiotics: From molecular mechanisms to pilot scale production

In this work, a simplified process from growth to spray drying of two probiotic strains, Lactobacilllus casei BL23 and Propionibacterium freudenreichii ITG P20, was proposed by utilizing concentrated sweet whey for growth and for achieving one-step drying of bacterial culture with higher dry matter of feed. Interestingly, after increasing the total solids of sweet whey from the original level of 5% to 20 - 30% (w/w), the two probiotic strains had higher final biomass production, instead of being inhibited by the high osmolality. The survival of the probiotics after spray drying was simultaneously improved, as well as during 6 months storage at 4 ºC. It was shown that this protective effect was due to enhanced multi-stress tolerance acquisition, overexpression of key stress proteins, and accumulation of intracellular storage molecules and compatible solutes upon growth in hyperosmotic medium