| Growth of three strains of Listeria monocytogenes in vacuum-packaged ground beef was investigated using a central composite design with storage temperature (0 to 10{dollar}spcirc{dollar}C) and fat content (11 to 39%) as two variables. L. monocytogenes failed to grow in meat obtained from a research abattoir because the natural microflora was dominated by bacteriocinogenic lactic acid bacteria. Growth of L. monocytogenes occurred in meat obtained from a commercial source and both temperature of storage and fat content were significant variables affecting their growth. Random amplification of polymorphic DNA showed that if growth of L. monocytogenes occurred in vacuum-packaged ground beef, all three strains grew. Leuconostoc gelidum UAL187 (bac{dollar}sp+{dollar}), L. gelidum UAL187-13 (bac{dollar}sp-{dollar}), or Leuconostoc sp. UAL280 (bac{dollar}sp+{dollar}) controlled growth of L. monocytogenes in co-inoculated vacuum-packaged ground beef compared with control samples. The results of the present study have shown that L. monocytogenes has the ability to grow at refrigeration temperatures in vacuum-packaged ground beef and its growth can be prevented with known lactic acid bacteria as biopreservatives. |
