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

Predictive models for the influence of intrinsic and extrinsic parameters relevant for gas-packed, cooked meat products on the growth parameters (maximum 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 gas-packed, cooked meat products and were included in the models. The concentration of CO2 in the aqueous phase of the food was chosen as the determinative inhibitory factor of modified atmospheres. All four investigated independent variables did influence significantly the growth parameters of L, monocytogenes. Interactions between temperature and CO2 and especially between CO2 and Na-lactate were observed. The model was validated in real gas-packed, cooked meat products and was then combined with previously developed models for spoilage of gas-packed, cooked meat pro ducts to determine the 'Risk Areas' for these type of food products. Low wafer activity cooked meat products supported out growth of L. monocytogenes before spoilage had occurred, unless Na-lactate and CO2 were applied as extra hurdles. (C) 2001 Academic Press.