Growth characteristics of Salmonella enteritidis in pasteurized and unpasteurized liquid egg products

Growth characteristics of a four-strain cocktail of Salmonella Enteritidis in commercial products of pasteurized and unpasteurized liquid whole egg were studied with a growth model developed by us. The unpasteurized product contained total bacteria at 10(7.3) CFU/g, but no Salmonella. When the products were spiked with Salmonella at various doses ranging from 10(1) to 10(4) CFU/g, growth curves of the pathogen at 24°C were well described with our model. Salmonella growth curves at constant temperatures from 8°C to 36°C in the two products were also well described with the model. The Baranyi model also described well most of the growth curves. The rate constants of growth for Salmonella at various constant temperatures were well described with the square root model. The maximum cell level, N(max) of Salmonella was constant at all temperatures in the pasteurized products, while a linear relationship between log N(max) and the temperature was observed in the unpasteurized ones. Salmonella growth in the unpasteurized product was highly suppressed in comparison with that in the pasteurized. This study also suggested the suitability of our model for application in the Salmonella growth analysis in pasteurized and unpasteurized liquid egg products.