Best Practices for Managing Listeria

This latter part of validation gets at the practical aspects of a control program, answering this critical question: how capable are the facilities at impeccably implementing the controls? In this part of validation, one needs to determine how to apply scientifically sound information to the particular process and plant. Possible considerations might include the availability of personnel to carry out the control, their level of expertise, the tools that might be needed, the type of equipment available, the age and condition of the facility, etc. This requires in-plant data collection, test results and other information demonstrating that the control can be operated within the particular establishment. The USDA Food Safety Inspection Service offers practical guidance on validation.

Image Credit: Ecolab US Inc.

4. Implement the controls. Once controls are identified and determined to be valid, they need to be continuously practiced, regardless of the operational or facility-specific factors that might affect them. Meaning, sales are up and you want to make more of a particular food product? Great, but the controls and practices cannot change. There needs to be continuous attention to these control mechanisms since they are directed against a serious potential hazard. This is the crux of establishment and practice of a food safety culture. A rule of thumb is to ensure that there is support to continually practice the control measure “irrespective of who’s looking!”

Leadership is essential. Senior management must provide appropriate resources including personnel, supplies, materials, etc. to carry out the controls. In addition, they need to offer support to the various team leaders and members to emphasize the importance of strict attention. Management must be engaged and keep employees well informed of the potential extent of the Listeria hazard and underscore the importance of the team’s work to actively manage the risk.

5. Verify that controls are consistently applied and be ready to modify them if needed. A key part of implementation is to verify that the system is operating according to the pre-determined plan. This is verification and this practice must be applied to every specific control measure to ensure that each is applied according to design. It allows for ongoing assurance by the plant that the control was done as designed.

There are many ways to verify. The particular facility needs to determine which procedure is best for its operation. Fresh eyes can help, so a review of records by someone other than the individual who recorded the results is a common practice. Another way is thermometer or water activity meter calibration or ensuring that plant equipment used for cooking is adequately set up. Sanitation verification that the surface is free of sensory detectable soils may be done via inspection for visual cleanliness or by sight, smell, or feel. Other sanitation verification practices include swabbing for residual adenosine triphosphate (ATP) after the cleaning step to show that the surface is free of detectable animal, plant, microbial, or human ATP.

Microbiological swabbing is also commonly used to verify effectiveness of sanitation. It should be done just after the sanitizing step or immediately before manufacturing if there is an extended time during which the sanitized equipment sits before production startup. Microbial swabbing could also be done at other times to identify Listeria harborages and allow for prompt implementation of appropriate corrective actions. Recently published guidance documents from Grocery Manufacturers Association and United Fresh Produce Association provide excellent information to help direct the development of a comprehensive Listeria swabbing program and provide input on the necessary corrective actions that could be followed. Although L. monocytogenes is the only member of the Listeria family that causes human illness, the presence of Listeria species in a food processing or handling environment may indicate that conditions are favorable for L. monocytogenes and appropriate actions should be taken.