Microwave-freeze drying was investigated as an alternative to conventional lyophilization to preserve the lactic acid bacteria Lactobacillus paracasei ssp. paracasei F19 (Lb. paracasei) and Bifidobacterium animalis ssp. lactis INL1 (B. lactis). The process parameters microwave power input (1.5–3 W∗g⁻¹) and chamber pressure (0.6, 1, 2 mbar) were varied. Drying kinetics, overall drying time, process stability and energy demand were assessed. Survival rate and cell membrane integrity were evaluated. Survival rate and membrane integrity after microwave-freeze drying were comparable to the standard lyophilization process for both cultures. For Lb. paracasei, survival could almost be maintained at all microwave-freeze drying process conditions. Best results in terms of process stability were achieved at 1 mbar and 1.5 W∗g⁻¹. For B. lactis, the highest survival of more than 90% was measured at 0.6 mbar and 1.5 W∗g⁻¹ microwave input. These conditions led to a drying time of 5 h, whereas conventional freeze drying lasted 24 h. A potential reduction of drying time compared to freeze drying of bacterial cultures of up to 80% renders microwave-freeze drying an alternative with comparable survival rates but higher efficiency.

研究了微波冷冻干燥作为常规冷冻干燥的替代方法，以保留乳酸细菌副干酪乳杆菌ssp。副干酪杆菌F19（副干酪杆菌）和动物双歧杆菌ssp。球菌INL1（乳双歧杆菌）。工艺参数微波功率输入（1.5–3 W * g ^-1）和腔室压力（0.6、1、2 mbar）有所不同。评估了干燥动力学，总干燥时间，工艺稳定性和能量需求。评估存活率和细胞膜完整性。微波冷冻干燥后的存活率和膜完整性与两种培养物的标准冻干过程相当。为了磅。副干酪的存活率几乎可以在所有微波冷冻干燥工艺条件下保持。就工艺稳定性而言，最佳结果是在1 mbar和1.5 W * g ^{-1下获得的}。对于乳酸双歧杆菌，在0.6 mbar和1.5 W * g ^-1微波输入下测得的最高存活率超过90％。这些条件导致干燥时间为5小时，而常规冷冻干燥持续24小时。与将细菌培养物冷冻干燥相比，干燥时间可能减少多达80％，这使得微波冷冻干燥成为具有相当存活率但效率更高的替代方法。