Listeria monocytogenes inoculated into refrigerated chicken breast fillets packed in modified atmosphere and irradiated: shelf life, natural microbiota and bacterial growth parameters

Abstract

The ability of Listeria monocytogenes and other bacteria to multiply on chicken breast fillets packaged in air, vacuum and modified atmosphere (80%CO₂/20%N₂),  irradiated (2 and 3kGy), and kept at 1ºC ± 1°C for up to 34 days was evaluated. Microbiological changes and pH occurring in samples were monitored. Bacteriological analyses indicated that both lag phase and shelf life increased with radiation dose. The samples packed in modified atmosphere and exposed to 3.0 kGy exceeded the initial 9-day shelf life of air-packaged fillets in 34 days. Lactic acid bacteria were the most resistant to gamma radiation and high CO₂ concentrations while coliforms and enterobacteria were the most sensitive. L. monocytogenes and Aeromonas spp. were able to grow in all samples. Irradiation increased the bacteriostatic effect of modified atmosphere packaging and can be used to improve microbiological quality and increase the shelf life of chicken breast fillets.