Growth properties of Listeria monocytogenes and predicting models in refrigerated milk

Listeria monocytogenes growth was evaluated by determining OD600 value and analyzing growth curves of strain in different conditions including culture ingredients,temperatures,p H values,Na Cl concentrations,inoculation amounts and rotation rates. The Gompertz,Logistic and Hill models were used to establish the growth models of L. monocytogenes in refrigerated milk.Results showed that the strain was grown well in TSB- YE and MRS medium and tolerant with 0.5% ~ 3%Na Cl concentrations. The optimal temperature was 37 ℃ and the optimal p H value was about 8 for growth. The oxygen demanding was not obvious for this strain. Cells were grown slowly in whole- fat milk at 4 ℃ with 2 lg CFU / m L increasing after attaining stationary phase,which Gompertz and Logistic models could be used in prediction of L.monocytogenes growth.