Modeling the growth rate of Listeria innocua influenced by coriander seed essential oil and storage temperature in meat using FTIR

The use of natural compounds to preserve food and the application of new tools for monitoring food safety is of great interest. In this study, the growth rate, including the lag time of Listeria innocua in ground lamb as a function of storage temperature (4, 10, 25, and 37°C) influence of the coriander seed essential oil (CEO), as an antimicrobial agent, was modeled. Fourier-transform infrared (FTIR) spectroscopy was used to monitor chemical changes in investigated specimens that may indicate spoilage in ground lamb. Results showed the use of CEO reduced growth rate of L. innocua, to approximately 0.0051 (CFU/h) for a sample containing CEO and to 0.042 (CFU/h) in control samples cultivated at 4°C. Increasing the cultivation temperature from 4 to 37°C led to a 5-fold increase of the growth rate (0.042 to 0.222 in the control sample) and 28-fold growth from 0.0051 to 0.147 in a sample containing the CEO. Minimum-recorded temperatures (Tmin) were –0.57 and 0.60°C for the control sample and a sample containing the CEO. The comparison of FTIR spectra of samples during the shelf life indicated that the increased shelf life and bacterial growth results in decreased moisture (1600–1650 cm–1) and protein content in the samples; while the intensity and sharpness of peaks increased in the range 1000–1100 cm–1, indicating the impact of bacterial activity on amounts of amines and amino acids. In conclusion, the CEO increased the L. innocua growth rate lag phase and improved the shelf life of the ground lamb. It is also recommended to use the FTIR to monitor the spoilage in meat.