Development and Validation of Predictive Model forSalmonella Growth in Unpasteurized LiquidEggs

摘要

Liquid egg products can be contaminated with Salmonella spp. during processing. A predictive model for the growth of Salmonella spp. in unpasteurized liquid eggs was developed and validated. Liquid whole egg, liquid yolk, and liquid egg white samples were prepared and inoculated with Salmonella mixture (approximately 3 Log CFU/mL) containing five serovars (S. Bareilly, S. Richmond, S. Typhimurium monophasic, S. Enteritidis, and S. Gallinarum). Salmonella growth data at isothermal temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) was collected by 960 h. The population of Salmonella in liquid whole egg and egg yolk increased at above 10°C, while Salmonella in egg white did not proliferate at all temperature. These results demonstrate that there is a difference in the growth of Salmonella depending on the types of liquid eggs (egg yolk, egg white, liquid whole egg) and storage temperature. To fit the growth data of Salmonella in liquid whole egg and egg yolk, Baranyi model was used as the primary model and the maximum growthrate and lag phase duration for each temperature were determined. A secondarymodel was developed with maximum growth rate as a function of temperature. Themodel performance measures, bias factor (Bf,0.96-0.99) and r² (0.96-0.99) indicated good fit for both primary andsecondary models. In conclusion, it is thought that the growth model can be usedusefully to predict Salmonella spp. growth in various types ofunpasteurized liquid eggs when those are exposed to various temperature and timeconditions during the processing.