A Concept for Rapid Prediction of Microbiological Reduction in Automatic Dish Cleaning Processes: The Microbiological Inactivation Equivalent (MIE) Unit

Abstract

The aim of this study was to establish a simple model describing the microbial reduction of a cleaning process by only using physical parameters of a given cleaning process (time and temperature) together with microorganism-specific inactivation parameters. The \Microbiological Inactivation Equivalent (MIE) unit" representing the time-temperature integral of a dish treatment process for a specific microorganism was developed. Microbiological reduction in suspension and dishwasher tests was tested in parallel. The microorganism-specific inactivation parameters were adjusted by fitting the MIE units to the experimental reduction factors gained. The mean square deviation between reduction factors and MIE units calculated was on average < 1 (Enterococcus faecium: 0.87, Micrococcus luteus: 0.79) in suspension tests and 1.09 (Enterococcus faecium) and 1.03 (Micrococcus luteus) in dishwasher tests. The MIE model can be used as a simplified method to predict the hygienic performance of a specific cleaning process under well-defined conditions.