Functional Foods Forum, University of Turku, 20014 Turku, Finland.
Functional Foods Forum, University of Turku, 20014 Turku, Finland.
Int J Food Microbiol. 2014 Mar 17;174:110-2. doi: 10.1016/j.ijfoodmicro.2014.01.006. Epub 2014 Jan 16.
The present study evaluated impact of moisture content and cell conditions on survival of probiotic strain, Lactobacillus rhamnosus GG, under lethal heat stresses and during long-term storage using freeze-dried cells and oils as matrices. Viable cell counts of freeze-dried L. rhamnosus GG cells suspended in oils had only 1-log-reduction after 5min at 80°C and approximately 3-log-reduction after 20min, while no or very few viable cells were recorded for freeze dried cells suspended in buffer and cultured cells in oils. Surprisingly, freeze-dried cells suspended in oils still contained 4.3 to 6.7logCFU/ml after 5min at 95°C. Long-term storage study indicated that freeze-dried cells suspended in oils kept viable conditions for 4months, and a loss of the viability was only 0.3 to 0.6logCFU/ml. Viable cell counts of cultured cells suspended in oils were not present after 3days to 3months. These results clearly indicate that moisture and cell conditions have a great impact on survival of probiotics under severe heat stress in processing and during long-term storage. Combination of freeze-dried cells and oils as carrier provides beneficial options to preserve viability of probiotics in food processes and storage.
本研究评估了水分含量和细胞状态对益生菌菌株鼠李糖乳杆菌 GG 在致死热应激下和使用冻干细胞和油作为基质进行长期储存时的生存能力的影响。悬浮在油中的冻干鼠李糖乳杆菌 GG 细胞的活菌数在 80°C 下仅 5 分钟就减少了 1 对数级，20 分钟后减少了约 3 对数级，而悬浮在缓冲液中的冻干细胞和悬浮在油中的培养细胞几乎没有或很少有活菌记录。令人惊讶的是，悬浮在油中的冻干细胞在 95°C 下仍能保持 4.3 到 6.7logCFU/ml 的活菌数。长期储存研究表明，悬浮在油中的冻干细胞可在 4 个月内保持存活状态，仅损失 0.3 到 0.6logCFU/ml 的活力。悬浮在油中的培养细胞的活菌数在 3 天至 3 个月后就不存在了。这些结果清楚地表明，水分和细胞状态对益生菌在加工过程中的严重热应激和长期储存中的生存能力有很大影响。冻干细胞和油的组合作为载体，为食品加工和储存过程中益生菌的活力保存提供了有益的选择。
