Development of microbiological criteria to assess the acceptability of a food lot – An example for milk powder

• Example microbiological criteria were developed for milk.
• Criteria are given for mesophilic aerobic colony count and Enterobacteriaceae as hygiene indictors.
• A food safety criterion was developed for Salmonella spp.
• We provide performance characteristics of the sampling plans for four different standard deviations.

Milk powder to be consumed without further treatment to inactivate microorganisms was selected to illustrate the process for establishing and applying a microbiological criterion to assess the acceptability of a food lot. Example criteria (size of analytical unit, sampling plan and limits) were specified for mesophilic aerobic colony count and Enterobacteriaceae as indicators of the adequacy of Good Hygienic Practices and for Salmonella as a food safety criterion. Performance characteristics were determined for each criterion using four values for standard deviation of the microbial counts to illustrate how sampling plan performance depends on the within-lot standard deviation, which is uncertain for any given lot and varies among lots. Methods of analysis were specified. A description of how to interpret the results and examples of actions that could be taken by food business operators and competent authorities are provided.