Growth of Listeria monocytogenes in modified atmosphere packed cooked meatproducts: a predictive model

Predictive models for the influence of intrinsic and extrinsic parameters r elevant for gas-packed, cooked meat products on the growth parameters (maxi mum specific growth rate and the lag phase) of Listeria monocytogenes were developed. Two types of models were compared, ie. extended Ratkowsky models and response surface models. Temperature, water activity, concentration of sodium lactate (SL) and dissolved CO2 in the aqueous phase were considered as the relevant parameters influencing the growth of L. monocytogenes in g as-packed, cooked meat products and were included in the models. The concen tration of CO2 in the aqueous phase of the food was chosen as the determina tive inhibitory factor of modified atmospheres. All four investigated indep endent variables did influence significantly the growth parameters of L, mo nocytogenes. Interactions between temperature and CO2 and especially betwee n CO2 and Na-lactate were observed. The model was validated in real gas-pac ked, cooked meat products and was then combined with previously developed m odels for spoilage of gas-packed, cooked meat pro ducts to determine the 'R isk Areas' for these type of food products. Low wafer activity cooked meat products supported out growth of L. monocytogenes before spoilage had occur red, unless Na-lactate and CO2 were applied as extra hurdles. (C) 2001 Acad emic Press.