Enhancing viability of dried lactic acid bacteria prepared by freeze drying and spray drying via heat preadaptation

Physical injury carried by dried process was an inevitable and hostile problem which could seriously affect the quality and viability of microbial agents. In this study, heat preadaptation was successfully applied as a pre-treatment to fight against the physical stresses encountered during freeze-dried and spray-dried process and develop a high activity Tetragenococcus halophilus powder. The results indicated T. halophilus cells maintained a higher viability in dried powder when cells were treated with heat preadaptation before dried process. Flow cytometry analysis illustrated that heat preadaptation contributed to maintain a high membrane integrity during dried process. Besides, glass transition temperatures of dried powder increased when cells were preheated, which further verified that higher stability was obtained in group preadaptation during shelf life. Additionally, dried powder prepared by heat shock presented a better fermentation performance, suggesting heat preadaptation may be a promising strategy to prepare bacterial powder by freeze drying or spray drying.

Automated summary

In this study, heat preadaptation was utilized as a pre-treatment to enhance the quality and viability of microbial agents during freeze-drying and spray-drying processes. Results showed that heat preadaptation significantly increased the viability of T. halophilus cells in dried powder. Flow cytometry analysis revealed that heat preadaptation helped maintain high membrane integrity during the drying process. Moreover, heat preadaptation resulted in higher stability and improved fermentation performance of the dried powder.