The Research Of Monitoring Technique About Listeria Monocytogenes On Fresh Agriculture Products

The groAwth models and dynamics of Listeria monocytogenes on fresh agriculture product in logistics process were established,in order to understand contamination situation of L.monocytogenes.In this paper,the effect of ambient temperature and initial concentration of L.monocytogenes suspension on growth of L.monocytogenes were investigated,the primary model of contaminative fresh-cut pears processed subacidity and alkalescence electrolyzed water,and sterile water was established.The content of the study includes:45 food samples of 4 kinds of foods(fruits and vegetables product,meat products,seafood and dairy products)were collected from Dalian Development Area and confirmed by National standard method and biochemistry kit.Predictive growth models of L.monocytogenes on nutrient broth were established under the different incubation temperatures(4 ?,26 ?,and 36 ?,respectively)and initial concentrations(102cfu/mL,103cfu/mL,104cfu/mL,respectively).Gompertz and Logistic model were used to fit the growth curve by Matlab software.The corresponding parameters,such as maximum specific growth rate(U),lag phase(L),and maximum population density(M),were obtained from above two models.The primary model of contaminative Fresh-cut pears processed subacidity and alkalescence electrolyzed water,and sterile water was established.The corresponding parameters were obtained from Gompertz and Logistic model.The efficiency of 3 kinds of sterilization was compared each other.The result demonstrated that:1.2 strains of L.monocytogenes were detected from 45 food samples,with total detectable rate of 4.44%,of which meat products and other products accounted for 9.52%and 0%,respectively.2.Growth primary model of L.monocytogenes on the nutrient broth was fit under the different temperatures and initial concentrations.Gompertz model showed a high correlation at all temperatures and initial concentrations.There was a positive correlation between temperature and the growth rate of L.monocytogenes.The lag phase was negative correlated with the maximum population density.The U value decreased as the initial concentration increased at the same temperature.At 4 ? the lag phase extended as the initial concentration increased,while lag phase shorten as the initial concentration increased under the both of 26? and 36?.The initial concentration was not significant influence on the maximum cell density at all temperatures.3.The primary model of contaminative fresh-cut pears processed subacidity and alkalescence electrolyzed water and sterile water was established.Logistic model showed a high correlation for contaminative Fresh-cut pears processed subacidity at 26 ?.Gompertz model was better at 4? and 36?.L.monocytogenes on the contaminative Fresh-cut pears could decrease 1.71g(cfu/mL)by subacidity electrolyzed water processed.Disinfection effect of subacidity electrolyzed water was better than without processed.Although the alkalescence electrolyzed water has a certain healthcare function,it has not disinfection function.The disinfection effect is not notable difference between the alkalescence electrolyzed water and sterile water.