The growth of Listeria monocytogenes in cheese packed under a modified atmosphere.
The effect of modified atmosphere Packaging (MAP) on the growth of Listeria monocytogenes in mould ripened cheeses was studied at refrigeration temperatures (2-8.3 degrees C) over a storage period of 6 weeks. Control experiments in cling film with no atmospheric modification produced a lag time before growth of up to 1 week and rapid subsequent growth. MAP with a CO2 concentration of less than 20% allowed growth to occur but when O2 was incorporated; the lag time was reduced from 3 to 2 weeks and subsequent growth was also faster, producing an increase in cell numbers of 1.4 log cycles over the incubation period. N2-MAP in the absence of O2 increased the lag time to 3 weeks and slowed growth, while the inclusion of CO2 extended the lag to 3 weeks and slowed subsequent growth even more. In MAP with 80:10:10 (v/v/v) N2:CO2:O2, there was a lag period of 2-3 weeks before growth of L. monocytogenes occurred, while the total viable aerobic count (TVAC) decreased by 2-3 log cycles and the total Lactobacillus count showed little change. It was concluded that MAP was not suitable for preventing the growth of L. monocytogenes in such cheeses.
Whitley
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University of Nottingham, Loughborough, UK. Elizabeth.Whitley@NTU.ac.UK
Muir
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Waites
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WM
D002245:Carbon Dioxide / Q000494:pharmacology; D002611:Cheese / Q000382:microbiology*; D003080:Cold Temperature; D018857:Food Packaging; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development*; D009584:Nitrogen / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology
D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen