EAS is pleased to introduce a new column in our EAS-e-News called Ask the Expert. Each month our expert consultants will answer one question sent in by readers. If you’d like to submit a question, please use the Contact Us link on our website.
Today’s question is answered by Allen Sayler, EAS’ Senior Director for Food Consulting Services and pertains to testing of Listeria species or monocytogenes. This question was asked at our recent webinar focusing on Listeria and the full list of questions asked by webinar participants as well as their responses are provided here.
Question: Is it recommended to test for Listeria species or monocytogenes for all four environmental monitoring zones as well as a finished product for RTE foods?
Sayler: It is not practical or financially possible to establish a finished product testing protocol for RTE foods that is statistically valid. Therefore, a limited finished product testing program that describes taking at least one sample for each day’s production or for each production lot would provide an adequate finished product testing program. It is our opinion that for those processing environments that are associated with moist conditions or the use of water for cleaning the floors, outside of processing equipment, etc.; an environmental monitoring program should be based on detecting Listeria species, with swabbing concentrated on Zone 3 (floors, walls, door knobs, floor drains). Zone 2 should only be included if there are a positive Zone 3 swab and a vectoring strategy implemented to identify the true source. For relatively dry processing environments, it is recommended that Salmonella be the choice for detection of environmental contamination. It is strongly recommended that ATP swabbing is utilized on clean and dry FCS (Zone #1). A calibrated ATP system can provide results within 1 minute and allow the sanitation crew to reclean and re-swab the FCS to ensure it has been effectively cleaned. This approach is “preventive” versus environmental swabbing and testing of Zone #1, which can take up to 48 hours to get results as well as a similar delay it obtaining results for finished product testing for the presence of L. mono. or Salmonella. Microbial testing of Zone #1 and the finished product is “reactive”, not preventive.