Pecorino di Farindola is a typical cheese produced in the area surrounding the village of Farindola, located in the Abruzzo Region (central Italy), unique among Italian cheese because only raw ewe milk and pig rennet are used for its production. In the literature it is well documented that raw milk is able to support the growth of pathogenic microorganisms such as Listeria monocytogenes. Predictive microbiology can be useful in order to predict growth-death kinetics of pathogenic bacteria, on the basis of known environmental conditions. Aim of this study was to compare predictions obtained from a model, originally designed to predict the kinetics of L. monocytogenes in the dynamic growth-death environment of drying fresh sausage, with the results of challenge tests performed during the ripening of Pecorino di Farindola produced from artificially contaminated raw ewe milk.

A challenge test was carried out using ewe raw milk inoculated with L. monocytogenes, in order to produce Pecorino di Farindola cheese stored at 18 °C for 149 days of ripening. During the ripening period, pH and a_w values decreased in all samples analysed; lactic acid bacteria become the prevailing microbial population, while for L. monocytogenes a period of stability (neither growth nor death) followed the initial situation. The growth inhibition and the following inactivation may mostly be due to competition with the autochthonous microbiota and to the reduction of water activity.

Mathematical modelling was used in order to predict microbial kinetics in the dynamic ripening environment, joining growth and death patterns in a continuous way, and including the highly uncertain growth/no growth range separating the two regions. The effect of lactic acid bacteria on the growth of pathogens was also included. Predicted microbial kinetics were satisfactory, as confirmed by the absence of statistically significant difference between observed and predicted values (p > 0.05).

The present study proved, via challenge tests, that a dynamic growth/death model, previously used for a meat product, can be fruitfully used in cheese characterized by active competitive microbiota and progressive drying during ripening.

Pecorino di Farindola是一种典型的奶酪，是在位于意大利中部阿布鲁佐地区Farindola村周围地区生产的，在意大利奶酪中是独一无二的，因为仅使用生母羊奶和猪凝乳酶来生产。在文献中有充分的文献证明，生牛奶能够支持病原微生物如单核细胞增生李斯特菌。根据已知的环境条件，预测微生物学可用于预测病原细菌的生长-死亡动力学。这项研究的目的是比较从最初设计为预测单核细胞增生李斯特氏菌动力学的模型获得的预测。在干燥香肠的动态生长-死亡环境中，采用人工污染的母羊牛奶生产的Pecorino di Farindola熟化过程中进行的挑战性测试结果。

使用接种单核细胞增生李斯特氏菌的母羊生乳进行了激发试验，以生产在18°C下储存149天成熟的Pecorino di Farindola奶酪。在成熟期间，所有分析样品的pH值和_w值均降低；乳酸菌成为主要的微生物种群，而对于单核细胞增生李斯特氏菌来说，一段稳定的时期（既不生长也不死亡）遵循最初的情况。生长抑制和随后的失活可能主要是由于与自生菌群的竞争以及水活度的降低。

使用数学模型来预测动态成熟环境中的微生物动力学，以连续的方式加入生长和死亡模式，并包括高度不确定的生长/没有生长范围将两个区域分开。还包括乳酸菌对病原体生长的影响。预测的微生物动力学令人满意，这通过观察值与预测值之间不存在统计学上的显着差异来证实（p> 0.05）。

本研究通过挑战性测试证明，以前用于肉类产品的动态生长/死亡模型可以有效地用于以活跃竞争性微生物群和成熟过程中逐渐干燥为特征的奶酪。