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From: Food Quality & Safety magazine, February/March 2005

Examples from the Real World

Staying competitive with a quality testing solution

by A.J. McCardell

Food companies that produce ready-to-eat products face a special challenge related to Listeria testing and prevention. Food quality and safety must be maintained while improving efficiencies and lowering costs at the same time. As environmental Listeria testing requirements increase to meet regulatory pressures, the job has become a little tougher. The biggest challenges with Listeria in a production environment are obvious--assuring you can find Listeria if it is present, eliminating it and preventing its return. Not so obvious-or easy-is acquiring a reliable Listeria testing solution that fits your real-world laboratory and production needs.

Finding the right solution

There are three key features to consider while evaluating a quality Listeria testing solution. First, the test method should be AOAC approved specifically for environmental samples if that is part of your testing program. AOAC-RI is the first level of validation that demonstrates a test method has been challenged and reviewed by a third-party. Although a number of Listeria test methods have AOAC approval, many of these have been validated on food matrices only, not on environmental samples. Environmental samples can contain sanitizers, additional background flora and other compounds, which can interfere with the performance of some rapid methods, rendering the results unreliable at best. Second, because most food companies cite elimination of false negatives as a critical issue in their testing programs, an environmental Listeria test method should be able to find all Listeria species at a detection level of one cell per sample. If your method does not detect certain Listeria species or has poor sensitivity, then you aren't getting the whole picture and false negatives may be an issue. On the other hand, your testing solution should have a very low level of false positives to reduce the amount of resources spent chasing false alarms. Finally, a method must make good economic sense, in other words "quality at the right price." While competitive pricing is a consideration, the hidden cost of adopting one method over another must enter the equation. Superior methods are designed to eliminate as many steps as possible while still achieving high quality results. Reducing the complexity of a test method has a number of benefits. The opportunity to introduce errors is greatly reduced and efficiencies are higher with methods that require less user intervention and hands-on time. Training costs, which are often overlooked, can also be reduced significantly when using a streamlined method. Higher efficiencies allow you time and resources for other activities and reduce the cost of your overall testing program.

Smithfield Foods Goes Above and Beyond

As a maker of ready-to-eat meats and a large pork producer, Smithfield Foods (Smithfield, Va.) focuses on applying a strategic model that strives to go beyond compliance. "We're always looking for opportunities to improve quality and safety," says Dr. Margaret Hardin, director of food safety for Smithfield. With more than 10 years of industry experience, Dr. Hardin is no newcomer to tackling food safety issues in a production environment. In fact, Dr. Hardin worked on Listeria in cooked ready-to-eat products in the early 1990s, before it was widely recognized as an important issue in food production and safety. Smithfield was looking to improve the sensitivity of their Listeria testing while at the same time keeping an eye on the "cost in use" of their method. The company evaluated several methods, opting for a rapid check, single-step enrichment system that can detect Listeria in 40 hours. "Of all the methods we evaluated..., [this] test was unique in its ability to improve the sensitivity and reliability of results, while at the same time improving work flow in the laboratory," Dr. Hardin says. "[This] test is simpler with far fewer steps requiring technician intervention. Because there is only one transfer in the entire test process, the opportunities to introduce error are greatly reduced and our efficiencies have vastly increased. This represents an overall improvement in quality as well as an improvement in the cost in use."

ABC gets the 1,2,3 of Detection

Mary Lee, vice president of microbiology for ABC Research Corp., a Gainesville, Fla.-based laboratory service group, works with food companies and aims at three primary criteria: Providing the best method at a low cost and meeting performance standards and regulatory requirements as well as the customer's turn-around time. Lee has a wide selection of Listeria testing solutions on hand at the ISO 17025 accredited lab to choose from, including cultural plating methods, PCR, ELISA, and rapid test assays. "[The] system fits in very well with a high-volume laboratory," she says. "A single-step enrichment, lower labor requirements, and easy to read results have reduced our overtime costs and improved laboratory efficiencies. In fact, we've been able to reduce our staffing by the equivalent of 1.5 full-time employees as a result of using the test," she says. "At the same time, the quality of the result we are providing to our clients has improved. In our hands, the false positive less than 0.2 percent based on cultural confirmations. This is much less than what we typically see with other methods in our laboratory." As USDA regulations are changed and implemented, Lee has seen the food industry become more informed about testing requirements and, as a result, more requests for Listeria testing. Demand for safer food supplies and the regulatory pressures that follow will continue to grow in the future. With careful planning and evaluation, companies can find the Listeria testing solution that satisfies the public, protects their brands and is easy on the bottom line. -FQ

A.J. McCardell, food safety business unit director for Strategic Diagnostics. Reach her at 302-456-6789 or



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