کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4370217 | 1616774 | 2006 | 9 صفحه PDF | دانلود رایگان |
The survival of Salmonella spp. in chorizos has been studied under the effect of storage conditions; namely temperature (T = 6, 25, 30 °C), air inflow velocity (F = 0, 28.4 m/min), and initial water activity (aw0 = 0.85, 0.90, 0.93, 0.95, 0.97). The pH was held at 5.0. A total of 20 survival curves were experimentally obtained at various combinations of operating conditions. The chorizos were stored under four conditions: in the refrigerator (Ref: T = 6 °C, F = 0 m/min), at room temperature (RT: T = 25 °C, F = 0 m/min), in the hood (Hd: T = 25 °C, F = 28.4 m/min), and in the incubator (Inc: T = 30 °C, F = 0 m/min). Semi-logarithmic plots of counts vs. time revealed nonlinear trends for all the survival curves, indicating that the first-order kinetics model (exponential distribution function) was not suitable. The Weibull cumulative distribution function, for which the exponential function is only a special case, was selected and used to model the survival curves. The Weibull model was fitted to the 20 curves and the model parameters (α and β) were determined. The fitted survival curves agreed with the experimental data with R2 = 0.951, 0.969, 0.908, and 0.871 for the Ref, RT, Hd, and Inc curves, respectively. Regression models relating α and β to T, F, and aw0 resulted in R2 values of 0.975 for α and 0.988 for β. The α and β models can be used to generate a survival curve for Salmonella in chorizos for a given set of operating conditions. Additionally, α and β can be used to determine the times needed to reduce the count by 1 or 2 logs (t1D and t2D). It is concluded that the Weibull cumulative distribution function offers a powerful model for describing microbial survival data. A comparison with the pathogen modeling program (PMP) revealed that the survival kinetics of Salmonella spp. in chorizos could not be adequately predicted using PMP which underestimated the t1D and t2D. The mean of the Weibull probability density function correlated strongly with t1D and t2D, and can serve as an alternative to the D-values normally used with first-order kinetic models. Parametric studies were conducted and sensitivity of survival to operating conditions was evaluated and discussed in the paper. The models derived herein provide a means for the development of a reliable risk assessment system for controlling Salmonella spp. in chorizos.
Journal: International Journal of Food Microbiology - Volume 107, Issue 1, 1 March 2006, Pages 59–67