Food Protection Connection: E. Coli: Help on the Way?

(reprinted from Dietary Manager, February 2007)

Following the September 2006 announcement of an E. coli-associated foodborne illness outbreak traced to fresh, bagged spinach from California—and another E. coli outbreak linked to Taco Bell on the East coast shortly thereafter—dietary managers are concerned.

Consumers are concerned, too. According to a survey of food writers and editors conducted by Hunter Public Relations this past fall, the spinach E. coli outbreak was the top-rated food news story in 2006.

Legislators are in on the problem, too. In December 2006, a group of US senators sent a letter to the FDA, the USDA, and the CDC calling for a joint task force to investigate the E. coli problem and report to Congress with findings and recommendations.

New Technologies

Fortunately, scientists are on board, as well. With the stakes and the worries high, the push to perfect new methods of destroying dangerous E. coli pathogens continues full-steam, with some promising results. Here is a tour of some emerging science:
Chemical sanitizers: Just as a foodservice operation can apply a chemical solution to work surfaces to destroy pathogens, so can a produce handling operation apply chemical sanitizers to food. Chlorine solutions are an example. They are approved for use in washing produce, with concentration limits set by the Environmental Protection Agency. However, they pose risks to the environment, and to workers exposed to the resulting gases.

New research at Purdue University uses a weak lactic acid solution instead. Sprayed onto produce, it has already proven highly effective in destroying germs like E. coli and Salmonella.

Yet another option under investigation is chlorine dioxide gas, which works extremely well on produce. However, it can oxidize the tips and edges of delicate produce, turning leaves brown. Practical methods for using it are under development, and a request for FDA approval is in the works.

Irradiation: This process of applying electron beams has been used in the food industry for well over a decade, but not on produce. Today, researchers are exploring methods that might work on spinach, tomatoes, and other produce, with the goal of preserving quality while destroying pathogens. One practical disadvantage so far is that the technology is expensive.

Electrolyzed water: At the University of Minnesota, food safety experts are piloting a form of electrolyzed water that can be sprayed on foods such as spinach and green onions. Researchers suggest the technology could be used along multiple points in the farm-to-fork process—from spray irrigation for crops, to produce washing before distribution, to misting in the grocery store. The process not only destroys E. coli, but wipes out other bacteria and viruses as well.

Combination systems: A key challenge with any sanitizing process with produce is preservation of food quality. There is a balance to achieve between bringing pathogen levels to a near-zero level (a 99.99% reduction in pathogens) versus maintaining the textures, appearance, color, and nutritive value of foods.

At the University of Illinois, investigators are testing combination technologies, such as ultrasound plus ozone to destroy Listeria bacteria. Another successful application is a combination of peroxyacetic acid, electrolyzed water, and chlorine on cut apples.

Pasteurization: A USDA research center in Pennsylvania has been pioneering a low-temperature pasteurization process for cantaloupes. (Think of pasteurized eggs in shells.) Three minutes at 76°C has proven effective in killing bacteria, but the process does not damage edible flesh or destroy nutrients. Afterwards, melons are sealed in bags and cooled.

Bacteriophages: Approved by the FDA in August 2006 for use on ready-to-eat meat products to destroy Listeria bacteria, bacteriophages are a fascinating application of a naturally occurring microbe. Think of them as "good" viruses that infect harmful bacteria by injecting their own genetic material into them. BActeriophages are very specific in their action. Today, research is underway to test bacteriophage mixtures effective in destroying E. coli and other foodborne pathogens.

Prevention is Still Key

As every dietary manager appreciates, food safety is a farm-to-fork commitment. Working near the end of the chain, dietary managers can have a tremendous impact on the safety of the food they serve. Yet, certain factors are beyond a dietary manager's control.

Fresh spinach and lettuce, for example, are often served in a raw state. Dietary managers do not have the luxury of cooking to endpoint time and temperature controls to ensure that final safeguard. (They do, of course, still have control in storage time/temperature, employee handwashing, prevention of cross contamination, and other practices.)

With products such as fresh produce, significant responsibility for safety resides in earlier steps of the farm-to-fork process. A set of good agricultural practices (GAPs) issued by the FDA in 1998 was designed to tackle potential hazards, such as contamination of crops with E. coli bacteria from uncomposted manure, irrigation with suspect water sources, harvesting with unsanitized knives, or storage with unclean ice.

In short, food protection is a complex process with many players. While dietary managers take charge of proactive sanitation practices in the foodservice setting, evolving industry expertise offers hope behind the scenes, targeting the entire farm-to-fork arena.

By Sue Grossbauer