Measurement and modeling of moisture content, pH, and Listeria monocytogenes growth and survival during ripening of Camembert cheese

This study was on measurement and modeling of moisture content, pH, and Listeria monocytogenes survival and growth characteristics during ripening of Camembert cheese. As is common in industrial practice, cylindrical Camembert cheese samples 108 mm (diameter)*32 mm (height) intended for retail markets were used in this research. The pH and moisture content were measured in different locations and semi-empirical pH model and Finite Element Method (FEM) moisture content model were developed based on the measured data. A dynamic growth model, called Camembert dynamic model (CDM) was also developed based on survival and growth of L. monocytogenes during ripening of Camembert cheese. The combined pH, FEM moisture content, and CDM model was termed the intergrated dynamic growth-finite element model (IDG-FEM) to predict the survival and growth of L. monocytogenes during ripening of Camembert cheese.; The pH values increased gradually with the ripening time. The locations had significant differences (P < 0.05) for each day of ripening. The pH values in top and bottom surface regions had higher values than in top middle and bottom middle regions. Also, the pH in the surface was higher than in the center. The day had significant effect (P < 0.05) on the pH values during ripening. There were similar values for each batch and section on each ripening day. In this research, a semi-empirical model was used to determine spatial pH distributions during ripening of Camembert cheese. The pH model calculated values had a good-fit with the experimental data. The R 2 values for all sets were greater than 0.95.; As a precursor to determining the measurement locations of moisture content, the water activity was measured at sixteen locations in this study. The results showed that there were no significant differences (P > 0.05) among three sections in each batch. Therefore, any section can be used to obtain representative water activity distribution during ripening. Based on water activity results, the space-time distribution of moisture content values in Camembert cheese during ripening was measured at five different locations. The locations had significant differences (P < 0.05) for each day of ripening. (Abstract shortened by UMI.)...