Estimating parametric distributions of storage time and temperature of ready-to-eat foods for U.S. households.

Home refrigeration temperatures and product storage times are important factors for controlling the growth of Listeria monocytogenes in refrigerated ready-to-eat foods. In 2005, RTI International, in collaboration with Tennessee State University and Kansas State University, conducted a national survey of U.S. adults to characterize consumers' home storage and refrigeration practices for 10 different categories of refrigerated ready-to-eat foods. No distributions of storage time or refrigeration temperature were presented in any of the resulting publications. This study used classical parametric survival modeling to derive parametric distributions from the RTI International storage practices data set. Depending on the food category, variability in product storage times was best modeled using either exponential or Weibull distributions. The shape and scale of the distributions varied greatly depending on the food category. Moreover, the results indicated that consumers tend to keep a product that is packaged by a manufacturer for a longer period of time than a product that is packaged at retail. Refrigeration temperatures were comparable to those previously reported, with the variability in temperatures best fit using a Laplace distribution, as an alternative to the empirical distribution. In contrast to previous research, limited support was found for a correlation between storage time and temperature. The distributions provided in this study can be used to better model consumer behavior in future risk assessments.