SLICED FRANKFURTER-TYPE SAUSAGE - INHIBITING LISTERIA-MONOCYTOGENES BY MEANS OF A MODIFIED ATMOSPHERE

Listeria monocytogenes (L. m.) is found in many meat products. There is a particular risk to the consumer if heat-treated products are contaminated as a result of faults in hygiene and the products are then stored for several weeks. Tests to determine the influence of carbon dioxide on the development of L. m. in sliced frankfurter-type sausage are reported in the present paper. The effect of 20, 30, 50 and 80 % by volume Of CO2 was examined at storage temperatures of 4.7 and 10-degrees-C. t was only at a CO2 concentration of 80 % vol. that L. m. was inhibited at all the temperatures tested. In samples stored with 50 % vol. CO2 L. m. was unable to grow at 4-degrees-C for the first 3 weeks. At a storage temperature of 7-degrees-C the bacterial count increased during the same length of time by 1.5 powers of ten, whilst at 10-degrees-C there was an increase of 3 powers of ten within only 14 days. Investigations with different gas volumes showed that the inhibiting effect of the carbon dioxide declined as the amount of gas decreased.