Impact of media culture, freeze-drying and storage conditions on preservation of Lacticaseibacillus paracasei 90: Viability and metabolic potential as a secondary culture in semi-hard cheese

Abstract

Freeze-drying is the main process used to preserve lactic bacterial cultures at an industrial level; however, their viability and metabolic activity can be affected not only by the process per se but also by storage conditions. This study investigated the effect of freeze-drying and long-term storage (14 months) on the viability and metabolic activity of Lacticaseibacillus paracasei 90 (L90) grown in three culture media. The freeze-drying process did not influence its culturability and viability, regardless of the culture media used. The storage of the freeze-dried cultures at room temperature had a negative impact on viability, culturability and its ability to grow and acidify milk. However, L90 was able to withstand a long period of storage at low temperatures (14 months, 4 °C) and keep the technological features desirable of a ripening culture. Overall, the results demonstrate the robustness of this strain as a secondary culture in the food industry.