Invisible to the human eye, pathogens are microorganisms that when ingested have the potential to be lethal. They can be introduced into meat and poultry at any point, starting from when the animal is alive to when it is being served for dinner, any time from farm to table.

Fortunately, established food-safety procedures have made the US animal protein supply chain one of the safest in the world. Still, occasionally, there’s a mishap, and no processor wants to be that occasion.

The most recent data from Atlanta-based Centers for Disease Control and Prevention (CDC) indicate that each year, roughly one in six Americans (or 48 million people) get sick from a foodborne illness – an array of illnesses caused by consuming foods (not just animal protein) contaminated with certain microorganisms. Though most are minor afflictions, CDC statistics show that these cause as many as 128,000 Americans to be hospitalized annually and about 3,000 to die each year.

But here’s the good news: these figures are down significantly from a decade ago. Still, continuous efforts are needed to effectively prevent pathogenic contamination and growth.

Invisible danger

Because the US meat and poultry industries produce such high-quality products, this may contribute to an increased food-safety risk. For example, years ago, it was easy to tell if a piece of meat had gone bad, as it became organoleptically undesirable due to the growth of spoilage microorganisms or lipid oxidation.

Today, to expand distribution, processors often incorporate ingredient and processing technologies to lower or virtually eliminate spoilage microorganisms from foods, extending product shelf-life so that it can travel longer distances and reach more customers. Without these inherent indicators suggesting that it is time to discard, pathogenic bacteria have more time to grow to numbers that can cause illness and sometimes lead to death.

Some pathogens were not previously known (new pathogens), others have newly arisen as foodborne (emerging pathogens) and others have become more potent or associated with other products (evolving pathogens), according to a paper entitled “Emerging Bacterial Pathogens in Meat and Poultry: An Overview,” published in Food and Bioprocess Technology (February 2010). The fact is that meat and poultry are susceptible to contamination by pathogens, with many foodborne diseases associated with consumption of meat and poultry.

For example, Campylobacter jejuni is most notably associated with undercooked poultry. Specifically, the paper notes that C. jejuni O:19 and other serotypes are common etiological agents of Guillain–Barré syndrome, a neuropathy due to autoimmune response. Ingestion of Salmonella bacterium, which is also associated with undercooked poultry, leads to salmonellosis. This can lead to gastrointestinal distress and fever. Escherichia coli have been associated with consumption of undercooked, contaminated ground beef. The key here is that if it is present in the protein, proper cooking should kill it.

That’s not an option with Listeria monocytogenes, a ubiquitous pathogen that is a major public health concern because of its severity. L. monocytogenes is found throughout the environment and in many foods, primarily animal-based products. It resists historical microbial growth inhibitors, such as salt and acidity, and readily grows at refrigerated temperatures. And though freezing temperatures will stop its growth, this hearty bacterium remains viable.

Controlling Listeria

Proper cooking and reheating of foods effectively controls Listeria; however, refrigerated foods such as ready-to-eat (RTE) meat and poultry products, especially products purchased through the deli or in a hand-prepared sandwich, are very susceptible to contamination. This is because these products are repeatedly exposed to microorganisms in the environment and do not require further cooking prior to consumption.

On Dec. 9, 2002, the US Dept. of Agriculture Food Safety and Inspection Service (USDA-FSIS) put into effect directive 10,240.3, which instructs inspection-program personnel on when and how often to inspect RTE meat and poultry products, such as deli-type meats and poultry that are sliced in the establishment or at retail, and hot dog-type products. The directive identifies antimicrobial agents formulated with sodium/potassium lactate and sodium diacetate as a means to have the RTE products classified as “low risk.” Establishments that produce low-risk products may be eligible for FSIS’s low-targeted verification testing program, meaning decreased frequency of product, food-contact surface and plant-environment testing. This translates to reduced testing expenses for processors.

Further, to help prevent outbreaks of L. monocytogenes foodborne infection, also known as listeriosis, on Oct. 6, 2003, USDA-FSIS implemented a rule (9 CFR 430) requiring manufacturers to take precautionary steps to better control product adulteration from L. monocytogenes. The rule allows manufacturers to use approved antimicrobials.

Recognizing the need for antimicrobial options beyond lactates and diacetates, in 2005 the American Meat Institute Foundation commissioned researchers at the Univ. of Wisconsin-Madison to evaluate antimicrobials that are Generally Recognized as Safe (GRAS) for a variety of food products other than meat and poultry. In the researchers’ final report published in June 2006, the scientists provided data showing that propionate, benzoate and sorbate can enhance the safety of high-moisture, RTE cured and uncured meat and poultry products and that addition of these antimicrobials has little negative impact on consumer taste preference. A number of suppliers of these ingredients are currently pursuing their use in RTE meat and poultry.

Play it safe

To best prevent foodborne pathogens from proliferating on meat and poultry, processors want to start with high-quality raw materials from healthy animals. Include hygienic slaughtering and butchering to avoid contamination of freshly exposed meat surfaces. Thoroughly cook products and ensure they are packaged and stored under proper temperature. Because cooked meats served cold are susceptible to contamination by L. monocytogenes, a proven antimicrobial should be included. In addition to the aforementioned ingredients, there are others that are recognized for their ability to retard spoilage microorganisms and have been shown to function effectively against pathogens.