Dynamic predictive model for the growth of <i>Salmonella</i> spp. in liquid whole egg and risk evaluation of egg white hydrolysates manufacturing process for spore formers: <i> Bacillus cereus</i> and <i> Clostridium perfringens</i>

A dynamic model for the growth of Salmonella spp. in liquid whole egg under continuously varying temperature was developed and validated. Liquid whole egg was inoculated with ca. 2.5-3.0 log CFU/ml of Salmonella spp. to obtain the growth data at several isothermal conditions (5, 7, 10, 15, 20, 25, 30, 35, 37, 39, 41, 43, 45 and 47 o C). A primary model (Baranyi model) was fitted for each temperature growth data and corresponding maximum growth rates were estimated. Pseudo-R 2 values were greater than 0.97 for primary models. The maximum growth rates obtained from each primary model were then plotted against temperature and modeled using the modified Ratkowsky 32 model. The pseudo-R 2 and root mean square error was 0.99 and 0.06 log CFU/g, respectively for the secondary model. A dynamic model for the prediction of Salmonella spp. growth under varying temperature conditions was developed by solving a combination of primary and secondary models using fourth-order Runga-Kutta method. The developed dynamic model was validated for two sinusoidal temperature profiles, 515 o C and 10-40 o C with corresponding RMSE values of 0.28 and 0.23 h -1 , respectively between predicted and observed values. The developed dynamic model can be used to predict the growth of Salmonella spp. in liquid whole egg under varying temperature conditions.