Department of Microbiology, Experimental Institute for Zooprophylaxis in Lombardy and Emilia Romagna, Brescia, Italy.
Lett Appl Microbiol. 2011 Sep;53(3):364-70. doi: 10.1111/j.1472-765X.2011.03118.x. Epub 2011 Jul 28.
The aim of the study was to evaluate the behaviour of Listeria monocytogenes in the conditioning liquid of packaged water buffalo mozzarella cheese (WBMC).
The conditioning liquid was contaminated with L. monocytogenes, and the contaminated samples were stored at four different storage temperatures: 5 and 10 °C for 22 days; 20 °C for 9 days; 20 °C for 3 days and then at 5 °C for 6 days. The results showed that L. monocytogenes concentration decreased when contaminated samples were stored at 5 °C. When WBMC was stored at 20 °C and at 10 °C, L. monocytogenes started to grow after a lag phase of 3 and 10 days, respectively. When samples were stored at variable temperature conditions, L. monocytogenes numbers showed a lag phase of 5 days.
Use of a conditioning liquid characterized by acidity and a correct storage temperature is able to counteract pathogen replication during shelf life. A high concentration of lactic acid bacteria was associated with effective control of L. monocytogenes but the role of lactic acid bacteria in WBMC conditioning liquid requires further investigation.
According to European regulations, food producers should be able to justify decision-making on the shelf life assigned to their products, taking into account reasonable storage conditions and use by consumers. The results of the trial yielded information for producers of WBMC and similar cheeses for decision-making on product shelf life.
本研究旨在评估单增李斯特菌在包装水牛奶酪（WBMC）调理液中的行为。
调理液被单增李斯特菌污染，污染的样品在四个不同的储存温度下储存：5°C 和 10°C 储存 22 天；20°C 储存 9 天；20°C 储存 3 天，然后在 5°C 储存 6 天。结果表明，污染样品在 5°C 下储存时，单增李斯特菌浓度下降。当 WBMC 在 20°C 和 10°C 下储存时，单增李斯特菌分别在 3 天和 10 天后的滞后期开始生长。当样品在变温条件下储存时，单增李斯特菌数量在 5 天的滞后期后显示出生长。
使用具有酸度和正确储存温度特征的调理液能够在保质期内抑制病原体的复制。高浓度的乳酸菌与有效控制单增李斯特菌有关，但乳酸菌在 WBMC 调理液中的作用需要进一步研究。
根据欧洲法规，食品生产者应能够根据其产品的保质期做出决策，并考虑到合理的储存条件和消费者的使用情况。试验结果为 WBMC 和类似奶酪的生产者提供了关于产品保质期的决策信息。
