Enhancing the viability of Lactobacillus rhamnosus GG after spray drying and during storage

Increasing knowledge about the human microbiome has led to a growing awareness of the potential of applying probiotics to improve our health. The pharmaceutical industry shows an emerging interest in pharmaceutical formulations containing these beneficial microbes, the so-called pharmabiotics. An important manufacturing step is the drying of the probiotics, as this can increase the stability and shelf life of the finished pharmabiotic product. Unfortunately, drying also puts stress on microbial cells, thus causing a decrease in viability. We aimed to examine the effect of different drying media and protective excipients on the viability of the prototype probiotic strain Lactobacillus rhamnosus GG after spray drying and during subsequent storage for 28 weeks. The presence of phosphates in the drying medium showed to have a superior protective effect, especially during long-term storage at room temperature. Addition of lactose or trehalose resulted in significantly improved survival rates after drying as well as during long-term storage for the tested excipients. Both disaccharides are characterized by a high glass transition temperature. Maltodextrin showed less protective capacities compared to lactose and trehalose in all tested conditions. The usage of mannitol or dextran resulted in sticky powders and low yields, so further testing was not possible. In addition to optimizing the viability, future research will also explore the functionality of cellular probiotic components after spray drying in order to safeguard the probiotic activity of the formulated pharmabiotics.