The effect of carbon dioxide on the shelf life of ready-to-eat shredded chicken breast stored under refrigeration.

The objective of the present study was to determine the shelf life of ready-to-eat cooked chicken breast fillets (shredded) stored in atmospheres that were modified with different concentrations of CO2 and to establish a relationship between the concentration of this gas and bacterial growth. The samples were divided into 7 groups with different packaging conditions: aerobiosis, vacuum, and 10, 30, 50, 70, and 90% CO2 (with the remaining volume filled with N2). All of the samples were stored at 4 ± 2°C for 28 d. During this period, pH tests and counts of aerobic heterotrophic mesophyll bacteria (AHMB), aerobic heterotrophic psychotropic bacteria (AHPB), Enterobacteriaceae, and lactic acid bacteria (LAB) were performed, and the gas compositions of the packaging atmospheres were verified. The pH of the aerobic packages increased during storage. However, the other treatments resulted in the opposite trend, with the CO2 concentration decreasing over the first 24 h and then remaining constant until the end of experiment. A gradual increase in the AHMB, AHPB, Enterobacteriaceae, and LAB counts was observed during storage; this increase was faster in the meat that was packed under aerobiosis conditions than in the other treatments. The treatments with a CO2 concentration above 10% exhibited lower Enterobacteriaceae growth, whereas LAB growth was discrete in all of the treatments, independent of the CO2 concentration. The shelf life of the samples packed with 90% CO2 was 28 d. Based on the AHMB and AHPB counts, the shelf life was 3 times longer than for the samples packed under aerobiosis conditions (9 d). The increased package CO2 concentration caused a reduction in the growth rate of the examined bacteria (r = 0.99), and treatment with 90% CO2 appears promising as a method with which to increase the product's shelf life.