EFFECTS OF GASEOUS ENVIRONMENT AND TEMPERATURE ON THE STORAGE BEHAVIOR OF LISTERIA-MONOCYTOGENES ON CHICKEN BREAST MEAT

Portions of skinless chicken breast meat (pH 5.8) were inoculated with a strain of Listeria monocytogenes and stored at 1, 6 or 15-degrees-C in (1) aerobic conditions; (2) 30% CO2 + air; (3) 30% CO2 + N2; and (4) 100% CO2. When samples were held at 1-degrees-C the organism failed to grow under any of the test conditions, despite marked differences between treatments in spoilage rate and ultimate microflora. At 6-degrees-C counts of L. monocytogenes increased ca 10-fold in aerobic conditions before spoilage of the meat, but only when the inoculum culture was incubated at 1-degrees-C rather than 37-degrees-C. In CO2 atmospheres growth of L. monocytogenes was inhibited on meat held at 6-degrees-C, especially under 100% CO2. By contrast, storage at 15-degrees-C led to spoilage of the meat within 2 d, in all gaseous environments, and listeria levels increased up to 100-fold. Differences in the behaviour of L. monocytogenes on poultry and red meats are discussed.