Research progress in the mechanism of freeze-drying in protecting the high vitality of probiotics

Abstract:

Adequate intake of probiotics helps in maintaining the homeostasis of the gut microbiota, which is of great significance for human intestinal health. However, probiotics are vulnerable to stress and necessitate stringent storage conditions in industrial settings, which pose challenges to the vitality maintenance of probiotics in transportation and shelf-life. Therefore, it is essential to develop the preparation process capable of protecting the high vitality of probiotics. Drying beneficial for sustaining probiotic vitality is often used to maintain the strain stability. Among the drying methods, freeze-drying is widely used. However, during the freeze-drying process, probiotics encounter environmental stress conditions, which lead to cellular damage and even death. Therefore, the freeze-drying protectants that can significantly improve probiotic survival rate have become a research hotspot in the industrial application of probiotics. This article systematically summarizes both the commonly used and the newly discovered protectants for freeze-drying of probiotics and elucidates their mechanisms of action. It provides an overview of the factors affecting cell viability post freeze-drying while outlining the prospective research directions of freeze-drying protectants. This review is expected to furnish theoretical substantiation for the development of freeze-dried probiotics with high vitality.