Effects of carbon dioxide on the fate of Listeria monocytogenes of aerobic bacteria and on the development of spoilage in minimally processed fresh endive

Minimally processed fresh broad-leaved endive (Cichorium endivia L.) were stored at 3 and 10 degrees C in modified atmospheres containing air, 10% CO2/10% O-2, 30% CO2/10% O-2, and 50%, CO2/10% O-2. The effects of these modified atmospheres on the fate of both aerobic bacteria and three strains of Listeria monocytogenes, was investigated. Increases in CO2 concentrations significantly reduced the growth of the aerobic microflora. The best preservation of the visual quality occurred on endive leaves stored in 10% CO2/10% O-2, whereas leaves stored in 30% CO2/10% O-2 and 50% CO2/10% O-2, and to a lesser extent in air, showed extensive spoilage after storage. Listeria monocytogenes was slightly affected at 3 degrees C by the modified atmospheres, as compared to air. At 10 degrees C, results varied between replicate experiments, but L. monocytogenes generally grew better as the CO2 concentration was increased. The three test strains behaved in a similar way. In conclusion, among the modified atmospheres tested, a modified atmosphere containing 10% CO2/10% O-2 resulted in improved visual quality of minimally processed fresh endive, without a marked effect on the growth of the aerobic microflora or of L. monocytogenes.