Background and Objectives: Listeria monocytogenes population is one of the effective parameters in the quality and durability of feta cheese during its ripening. Reducing this population is one of the important problems for manufacturers. This study was carried with the aim of modeling the effect of the free form of nisin on reduction of listeria monocytogenes population in feta cheese using cellular automata; while saving time and cost to perform biological experiments, important issues analyzed in this model.

Materials and Methods: In this paper, we used capabilities of cellular automata such as simplicity of structure, being formulated, and producing interesting and complex behaviors of simple cells to provide a model. For this purpose, first, we defined the characteristics and rules of listeria monocytogenes and nisin. Then we executed the resulting model for two states (i.e. lack of nisin and presence of nisin in free form) by Netlogo simulator and in five time periods. Finally, the results of the runs were observed and analyzed in the form of graphs and values.

Results: The results showed that in the absence of nisin, durability and stability of quality cheese during ripening will not be increased. Moreover, the addition of nisin in free form had no influence on the quality of cheese, and even in this state, the rate of reduction of listeria monocytogenes population was lower than in the state of the absence of nisin.

Conclusion: Our analysis demonstrated that cellular automata is a powerful tool for modeling the effect of the free form of nisin on reduction of listeria monocytogenes population in feta cheese. Also the results showed that this model is a good starting point to create models for assessing the durability of a wide range of food products.

Keywords: Cellular Automata, Listeria Monocytogenes, Netlogo, Nisin