back to Organic Consumers Assn. Stop Food Irradiation page

New pathogen-controlling ingredients emerge

10/31/2000

Contents

• Cetylpyridinium chloride: versatile killer, pending approval
• Acidified sodium chlorite: approval after approval
• Activiated lactoferrin: Beats bugs irradiation won't
• Vaccines: additional control, at the source

The meat industry's continuing effort to control deadly pathogens inside meat plants and meat products is shifting focus from heavy technology such as steam vacuums and acid-wash cabinets to natural antimicrobials and pathogen-killing ingredients.

The latest developments in these areas were offered recently at a cutting-edge session of the Meat Industry Research Conference (MIRC), held in conjunction with October's American Meat Institute convention in Las Vegas, NV.

The emphasis is on control. "We're not trying to eradicate E. coli O157:H7," said Dr. Andrew Potter, one of the session's speakers, about one of the meat industry's most problematic pathogens. "We're not very good at eradicating. But we are good at controlling."

"Nature is pro-life," commented Dr. A.S. "Narain" Naidu, another speaker. "Nature is perfect. It will always adapt."

That makes control, much less eradication, of pathogens a daunting challenge. But an array of natural and ingredient antimicrobials, including cetylpyridinium chloride, acidified sodium chlorite, and activated lactoferrin, individually and in concert yield impressive results in the battle to keep pathogens out of the food supply. In addition, Potter has created a vaccine to help control E. coli O157 growth in cattle, which several studies have established to be the source reservoir for O157 in the food chain.

Cetylpyridinium chloride
Cetylpyridinium chloride, developed by Safe Foods Corp. under the brand name "Cecure," is a versatile ingredient with several application options: pre-chill, post-chill, and pre-package. It can be used in ready-to-cook, ready-to-eat, and processed products manufactured from poultry, meat, and fish, and has shown to be an effective microbial control on fruits and vegetables as well. Cecure can also be applied as a plant sanitizer.

In fact, the ingredient is already in widespread use in most American households, as the effective agent in mouthwashes and throat lozenges. According to Safe Foods' research, Cecure is effective against a broad spectrum of illness-causing pathogens, including Salmonella, Listeria monocytogenes, Campylobacter, and E. coli O157:H7.

Studies show no adverse organoleptic effects when Cecure is applied properly; it does not impact flavor, texture, appearance, or the odor of foods. Its pH is near neutral, and Cecure is stable, non-volatile, and soluble in water.

According to Jim Marsden, professor of food science at Kansas State Univ., who presented the paper on cetylpyridinium chloride at MIRC on behalf of Dr. Amy Waldroup of Safe Foods Corp., Cecure's stability in water allows the ingredient to misted on products, a cost-effective application method.

A Kansas State study recently showed that Cecure resulted in a six-log reduction of Listeria monocytogenes on ready-to-eat frankfurters. At a commercial poultry processing facility in California, Cecure reduced Salmonella, E. coli, Campylobacter, Listeria, and Staphylococcus counts by more than four logs.

In another study, conducted by USDA's Agricultural Research Service at the Department's Clay Center, NE, research facility, O157, Salmonella, and total plate counts in beef were all extensively controlled by Cecure, even up to 35 days after treatment.

Additionally, a study made by the University of Arkansas's medical sciences school shows extremely effective control of O157 by Cecure on fruits and vegetables. (The first work on cetylpyridinium chloride as a food-safety agent was done by UA's medical school, according to Marsden.) USDA's aquaculture research center in Arkansas also found Cecure to be an effective control for Listeria in fish.

Before meat processors rush out to buy Cecure by the sack, they need to be aware that cetylpyridinium chloride is not yet approved by USDA or FDA as a food ingredient -- in fact, it is still regulated by FDA as an over-the-counter drug. Marsden, however, told the MIRC audience that research has shown the ingredient produces no evidence of endocrine or reproductive toxicity, that its transport across biological membranes is limited, it accumulates only in very low numbers in aquatic organisms, and that heat tests, even at 205 degrees C for 30 minutes, show Cecure to be non-mutagenic. To sum up, Marsden thinks USDA and FDA approval will come soon.

"It's an extraordinarily effective antimicrobial on meat-borne pathogens," he said.

Acidified sodium chlorite

Acidified sodium chlorite (ASC), a combination of citric acid and sodium chlorite in an aqueous solution that's marketed by the Alcide Corp. under the tradename "Sanova," has also proven to be an effective microbial control in meat products, according to G. Kere Kemp of Alcide. It works by attacking sulfide and disulfide linkages, and makes non-specific attacks on the amino acid components of bacterial cell components.

Sanova's victims include pathogenic bacteria, viruses, fungi, yeasts, molds, and some protozoa.

The ingredient can be applied as either a spray or immersion dip; its residue -- primarily chloride and chlorate salts -- is safe. Unlike cetylpyridinium chloride, acidified sodium chlorite is approved as a food additive by both USDA and FDA for use on meat, poultry, seafood, and fruits and vegetables; it is also approved by EPA as a pesticide for use on food-contact surfaces.

"It is the most broadly approved antimicrobial additive," said Kemp. Non-food commercial uses include sterilization and disinfectant applications in hospitals, dental labs, and pharmaceutical clean-rooms. ASC is also used in the dairy industry for teat antisepsis. In a meat plant, USDA approval includes whole carcass pre-chill treatment, and carcass parts, trim, and organ-meat post-chill treatment.

The Department and FDA are presently reviewing approval for use in comminuted and formed ready-to-eat products, including hot dogs and other sausages.

Kere reported a 1999 Texas A&M study that showed Sanova to be an effective control of both O157 and Salmonella typhimurium. Water washes alone reduced O157 and Salmonella counts on inoculated beef carcasses by 2.3 logs, but a second treatment with 1,200 ppm ASC resulted in another 2.3 log reduction for both pathogens, for a total reduction of 4.6 log. Another study, done at Kansas State, gave similar results for inoculated beef carcasses.

A prototype application in a commercial slaughter plant involves application of ASC at 1,000 ppm after pre-chilled carcasses are water-rinsed. The 10-second ASC treatment brought down total plate counts 1.28 log on pre-chill carcasses, and 1.56 log on post-chill carcasses. In both cases the count for O157 was zero. The application technology involved a stainless steel cabinet in which circular spray rings apply misting Sanova.

Though government approval for ASC on beef trim is still pending, a commercial prototype system has already been developed and tested. Experiments were conducted on 90% lean and 50/50 trim following storage for 24 hours at four degrees C. The product was inoculated with a five-strain cocktail of non-pathogenic E. coli, and later sprayed, in a production throughput of 20,000 pounds per hour, for 15 seconds with a 1,000-ppm ASC solution (three fluid ounces per pound). Log reduction of E. coli was 2.1, and total coliform log reduction was 2.2.

In pork work done at Colorado State Univ., contaminated pork tongues were surfaced-rinsed for 30 seconds with a 1,200-ppm ASC solution; E. coli counts dropped by 2.0 logs to 0.5 log cfu/ml.

A Kansas State study on frankfurters focusing on ASC effectiveness with Listeria found that a 15-30 second ASC dip or spray treatment resulted in 3.0 log reductions, while a water wash gave only a 1.2 log reduction. The most effective treatment on frankfurters proved to be a 30-second dip.

Kere summed: "ASC can be expected to consistently deliver two-log reductions of pathogens on carcasses, parts, trim, and organ meats."

Activated lactoferrin

The work by Dr. Narain Naidu of California State Polytechnic Univ. with activated lactoferrin, a biological pathogen intervention, has already received considerable attention in the meat industry, and has led to a formal relationship between Naidu and Farmland National Beef. (See June's article on this site, Farmland Beef to Deploy Dairy-Based E. Coli Killer ).

Lactoferrin is almost a too-obvious natural antimicrobial control: found throughout Nature, it is the critical ingredient in mammalian mother's milk that provides suckling babies anti-pathogenic protection.

In fact, there is lactoferrin in meat naturally, said Naidu, who has been working with lactoferrin for more than 15 years, but it isn't activated. He uses an FDA-approved generally recognized as safe (GRAS) compound to activate lactoferrin for meat applications.

As he showed the MIRC audience in a series of slides, activated lactoferrin removes fimbria, which comprise the web of fibers a pathogenic bacterial cell uses to attach itself to a host; once exposed to lactoferrin, pathogens can't attach. Lactoferrin's effectiveness in this process is impressive: Studies have shown that a one-percent activated lactoferrin formulation knocks down O157 and gram-negative enterics by six logs, and gram-positive cocci and bacilli by three logs. It kills radiation-resistant bacteria -- yes, there are bacteria that low-dose irradiation won't kill -- by three logs.

Is it safe? Naidu again stressed its presence in natural products.

"At the application levels we are using, there is a thousand times more lactoferrin found in a single glass of milk." The lactoferrin used by Naidu in his work comes from whey.

So far, Naidu has published research demonstrating activated lactoferrin's effectiveness as an antimicrobial in beef products. He is expanding that research to cover pork, poultry, and processed meats, and results from in-plant tests will be available soon. He also expects USDA and FDA approval soon.

Vaccines

Meanwhile, the work of Dr. Andrew Potter of the Veterinary Infectious Disease Organization at the Univ. of Saskatchewan concentrates on controlling E. coli O157:H7 at the source: inside the animal. To that end, he and his research team have developed an O157 vaccine.

Vaccines, he said, are effective controllers, not eradicators. He noted that smallpox, for which there has been a vaccine for decades, was finally eradicated only in 1980, and polio will be finished off, finally, this year. Measles is expected to be eradicated sometime between 2005 and 2010. These are the only three human diseases to have been eradicated.

Nonetheless, vaccines are very good at what they do, and for an industry obsessed with controlling O157 that's good news. "Pretty well all animals see O157 something in their lifetimes," Potter said at the MIRC.

"You find it everywhere in a feedlot -- in feces, in the water, everywhere."

His O157 vaccines are adhesin-based, and, like activated lactoferrin, attack O157's attachment mechanism. "This is a clever organism. Anytime it wants to attach itself, it can, through delivery of what's called a TIR protein." After studies with 40 beef cattle showed promise, Potter's team is preparing vaccine field trials involving "thousands of animals," he said.

"The worst O157 outbreak in Canadian history was last summer," he pointed out, referring to an Ontario epidemic that was traced to groundwater polluted by cattle feces. "So the motivation to get the vaccine on the market quickly is great."

Dr. Xintian Ming of Rhodia Foods and Myron Nicholson of Viskase Corp. jointly presented data regarding an intriguing project: antimicrobial-treated sausage casings for ready-to-eat cooked products. A shirred casing containing the antimicrobial called Novasin and beta-hop acid (BHA) was very effective at killing Listeria monocytogenes, according to Ming and Nicholson, who said that a "significant synergy" was built by the Novasin and BHA. In short: "We found that casings can be an effective vehicle to deliver antimicrobial activity." Government approval of the treated casings is "in process," according to the researchers.

By Steve Bjerklie, Contributing Editor. Steve Bjerklie is contributing editor for Meat and Poultry Online and editor-at-large for Meat Processing Magazine. He also covers the food industry and American politics and culture for The Economist and many other publications.