含水量对植物乳杆菌冻干粉细胞活性的影响及其贮藏稳定性的研究

应用真空冷冻干燥技术，研究不同含水量对冻干产品中植物乳杆菌细胞活性的影响和不同保藏温度条件下样品中细胞存活率与复苏活力随时间变化的规律，并建立适用于判定菌体细胞冷冻干燥工艺终点的有效方法。结果表明：具有不同含水量的样品中，植物乳杆菌细胞的存活率间无显著性差异，但随着样品中含水量的降低，植物乳杆菌细胞进入对数生长期的时间逐渐延长，复苏活力也呈下降趋势。贮藏稳定性实验结果表明，－ 20℃条件下，植物乳杆菌细胞的存活率一直呈现上升趋势，到第515 天可达91.46%；4℃条件下，28d 内植物乳杆菌细胞的存活率呈上升趋势，到第515 天其存活率又下降到53.16%。综上所述，解析干燥初期是植物乳杆菌菌体冻干工艺理想的终点，比较适于植物乳杆菌发酵剂短期和长期保藏的温度条件分别是4℃和－ 20℃。

Effect of Water Capacity on Cell Activity and Storage Stability of Lactobacillus plantarum Starter Cultures

Lactobacillus plantarum starter cultures were freeze-dried under vacuum, and the effect of water capacity on cell survival rate and viability of Lactobacillus plantarum during storage were studied. Results showed that there was no significant difference among the cell survival rates of Lactobacillus plantarum of different water capacity, but with the decrease of water capacity of Lactobacillus plantarum, the time of Lactobacillus plantarum logarithmic growth phase was postponed and the cell viability declined. The cell survival rate of Lactobacillus plantarum increased during storage under －20℃ and up to 91.46% on day of 515th, while the cell survival increased under 4℃ before 28d, and drop to 53.16% on day of 515th. In conclusion, the early stage of secondary drying phase was the ideal terminal point of freeze-drying. 4℃ was good for short time storage for Lactobacillus plantarum, while －20℃ was a better choice for longer time storage.