Food Safety Magazine, April/May 2012

TESTING

will be found, but does not necessarily indicate an unsafe condition. Likewise, finished product testing is not likely to be as sensitive to detecting potential contamination as environmental monitoring. However, environmental monitoring programs should be designed to find harborages, not just meet customers’ expectations for Listeria testing. Microbiologists skilled in Listeria detection should be consulted to develop a series of rotating monitoring points to detect when Listeria has invaded the processing area, and these should be tested vigorously (e.g., avoid wasting efforts on smooth surfaces; swab weld joints and hidden surfaces instead). Initial findings of Listeria spp. should lead to more aggressive cleaning and sanitizing in the area and retesting. If retesting yields negative findings, then the operation should go back to normal monitoring of the area. If retesting yields positive findings, then the Listeria may have found a harborage point, which needs to be found through extensive testing and eliminated like any pest. Listeria is a pervasive microorganism and has found harborage in unlikely places, such as hollow ladder rungs, hollow conveyor rollers, facility walls and chill tunnel insulation.

The tragic outbreak last year demonstrated that packinghouses might be as vulnerable to Listeria harborage and product contamination as fresh-cut operations. While Listeria is not likely to become entrenched in dry environments, operations or equipment that are routinely wet are vulnerable. Additionally, packinghouses that are not routinely held at the cold temperatures of fresh-cut operations can be even more vulnerable; while Listeria has a competitive advantage because it can survive and grow in cold environments, it likes warmer environments even more. For more information about L. monocytogenes and environmental monitoring programs, operations should consult;FDA’s;Bad Bug Book, 3;FDA’s Listeria guidance for industry, or a commercial laboratory experienced in Listeria and environmental testing. n

David E. Gombas, Ph.D., is the senior vice president, food safety and technology, at the United Fresh Produce Association.

References

1. www.fda.gov/food/ guidancecomplianceregulatoryinformation/ guidancedocuments/foodprocessinghaccp/ ucm073110.htm.

2. Tompkin, R.B., V.N. Scott, D. T. Bernard, W.H. Sveum and K.S. Gombas. 1999. Guidelines to prevent post-processing contamination from Listeria monocytogenes. Dairy Food Environ Sanitation 19:551–562. 3. www.fda.gov/food/foodsafety/ foodborneillness/foodborneillness foodbornepathogensnaturaltoxins/badbugbook/ ucm070064.htm.

Checkweighing HI-SPEED Metal Detection & X-ray Inspection SAFELINE Vision Inspection CI-VISION
Food Safety Regulation
Compliance Resources

METTLER TOLEDO has long been the product inspection industry leader in food
safety education with our Safeline metal detection and x-ray inspection brand.
We have launched a year-long initiative to provide you with the right training,
educational materials and product solutions that will enable you to navigate the food
safety regulatory environment with confidence.