The biggest change occurring with antimicrobial ingredients is the increased use of natural antimicrobials, especially in the formulation of cured products.

For example, natural nitrite or vegetable-derived nitrite is growing, says Peter Muriana, professor in the Department of Animal and Food Sciences at Oklahoma State University (OSU) in Stillwater and food microbiologist for the Robert M. Kerr Food and Agricultural Products Center in Stillwater.

“Vegetables are loaded with nitrate, and bacterial fermentations convert the nitrate to nitrite,” he explains. “Ingredient companies do this and provide vegetable extracts, i.e., nitrite, for meat processors. USDA-FSIS has decided that since greater than 95 percent of human exposure to nitrite is via consumption of vegetables, and their nitrate is converted to nitrite by organisms in the GI tract, that if companies use vegetable-derived nitrite, then they can label their product as ‘no added nitrites,’ or ‘no added preservatives.’”

An exception to this rule would be what is found naturally in celery. If processors are using celery-derived nitrite, they cannot call the product “cured,” which by standard of identity is with sodium nitrite, Muriana explains. Sodium nitrite to inhibit spore germination by Clostridium is pure sodium nitrite, except for the salt as a carrier while vegetable-based nitrite is a fermented-vegetable extract and has substances from the fermentation in addition to sodium nitrite.

“Companies like the clean label and saying ‘no nitrites added’ on their products even if they can’t call their products ‘cured,’” Muriana says.

Bacteriophages and bacteriocins

The latest developments for antimicrobial ingredients being used in ready-to-eat meat and poultry products also include the use of bacteriophages and bacteriocins, says Lynn Knipe, extension processed meat specialist and associate professor in Food Science and Technology and Animal Sciences at Ohio State University, in Columbus. Phages are bacteriocidal, which means they kill pathogens, and are applied to the surface of products where pathogens such as Listeria are present.

“Advantages to the phages are that they are organic, so they will work for clean-label products, plus they contribute no off flavors to the product,” he says.

Bacteriocins are being used in traditional, Italian salami-type products that are fermented but not heat treated. The bacteriocins are produced by organisms in the starter culture and are specific for Listeria, Knipe says. 

The buffered citrates and vinegar products along with bacteriophages seem to be on the increase in response to consumer pressure for clean labels, Knipe says. “Another advantage to these products is that most are effective in inhibiting both L. monocytogenes and C. perfringens growth over the refrigerated shelf life of the product,” he says.

While phages are organic and contribute no flavors to the product, they are specific to one pathogen at a time, e.g., Listeria, Salmonella, etc.

Muriana says phages are an area to watch in antimicrobial ingredients, but are limited by specificity and application processes. Phages are more effective when applied topically to target bacteria on the surface of products. Phages currently do not work well once mixed into food products, he says.

Naturally derived antimicrobials, especially plant-based, and biocontrol products such as phages, lactic acid bacteria and bacteriocins are becoming extremely popular, says Divya Jaroni, associate professor in the Department of Animal and Food Sciences at OSU.

“Natural and biocontrol-based are particularly growing in meat and poultry due to consumer demands for natural products, and industry is trying to fulfill those demands,” says Ravi Jadeja, assistant professor in the Department of Animal and Food Sciences at OSU and food safety specialist for the Robert M. Kerr Food and Agricultural Products Center. “Phage-based products are gaining interest due to recent FDA approval of a Listeria-specific phage product. Foodborne pathogens tend to develop resistance toward conventional antimicrobials, but use of phage-based products could overcome this problem. Chlorine and other conventionally used ingredients are declining for the same reason.”

The lactates and diacetates that the industry started with may be seeing a decline in use because of the many other options now available as well as the potential off flavors that can result in mildly seasoned products, Knipe says.

Moving forward, Knipe expects the industry will turn to more ingredients produced like the bacteriocins, in which a chemical that could cause a problem on a clean label isn’t used. Instead, the industry will use an antimicrobial ingredient produced during a fermentation process. Many of these antimicrobial peptides produced by bacteria, especially lactic acid bacteria, can be heated at fairly high temperature while retaining antimicrobial activity, Muriana says.

Processors also are faced with each antimicrobial either being bacteriocidal, which kills pathogens on contact, or bacteriostatic, which inhibits future growth of existing pathogens, but not both. 

“To optimize these two characteristics, processors can combine antimicrobials, which do both kill and inhibit pathogens,” Knipe says. “This should also allow processors to use lower levels of both ingredients and be even more effective than using one or the other.”

While approval from regulatory agencies, cost effectiveness and meat quality are some of the key challenges for processors moving forward, conducting more research and validation studies are some of the ways the industry is working to overcome these problems, Jadeja says. NP