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Method combines ozone and ionization to kill pathogens

By staff reporter , 26-May-2006

Transforming a method originally developed to decontaminate spacecraft could be new means of destroying pathogens in processing plants, according to scientists.

Scientists at Kansas State University are working with EcoQuest International of Greenville, Tenn., to investigate a way of using ozone along with ionization to reduce several pathogens, including E. coli and Listeria monocytogenes, in food processing plants. The method was originally developed by the US National Aeronautics and Space Agency to decontaminate spacecrafts during long missions.

With the increasing emphasis by consumers and regulators on food safety, and the prospect of costly recalls, fines and brand damage, processors are constantly on the lookout for quicker and cheaper ways of preventing bacterial contamination of their products.

 

The new food safety technology consists of an antimicrobial part that uses oxidated gases such as peroxide and ozone and the ionized part, said James Marsden of the university's Food Safety Consortium research unit.

 

"Here we're talking about oxidated gases that basically fill the room with a somewhat aggressive antimicrobial system - extremely safe and breathable," Marsden said.

 

The levels of ozone are very low in terms of standards set by the Occupational Safety and Health Administration and the Food and Drug Adminstration, he said.

 

The researchers used stainless steel surfaces to test the system's effectiveness in removing contaminating bacteria. The ionization system removed more microbial populations than ozone at shorter exposure times, they claimed in the spring issue of the Food Safety Consortium's newsletter.

 

Ozone already has a good track record as a disinfectant. In 2001 the FDA approved its use as a sanitizer for food contact surfaces and for direct application to food products. It is also used extensively for purification of bottled and municipal water.

 

"In the meat and poultry industry there are some applications for ozone where products are being treated with aqueous ozone prior to being sliced," Marsden said. "They're looking at ozone for decontamination of poultry chillers and for direct decontamination of birds as they go down the processing line."

 

Five years since government approval of the process is not a long time to determine how well applications are going to work, particularly in the meat and poultry industry, he said.

 

The scientists and EcoQuest will also examine its effectiveness in inactivating avian influenza environmentally. They may also investigate how the system could control Listeria in ready-to-eat meat processing plants.

 

The recent research results showed that ionization was effective in reducing levels of Staphylococcus auerus, leading researchers to consider the implications for hospitals and nursing homes.

 

"The ionization effect is that it eliminated odors," Marsden said. "For odors to be present they have to be aeromatic, so if you take it out in particle form and inactivate further with peroxide and ozone, it might have some application as well in hospitals, nursing homes and the food industry."

 

Marsden likens a new process using ionization to a "miniature sun" of ultraviolet energy interacting with oxygen and drawing particles out of the air, thus producing an antimicrobial effect.

 

"When Mount St. Helens went off, you had all these particles floating around," he said. "The reason they're not still floating around is that ionization from the sun caused them to fall out of the air."

 

Ozone decays quickly in water, thus, its use may be considered as a process rather than a food additive, with no safety concerns about consumption of residual ozone in food products. Ozone has been used with varied success to inactivate microflora on meat, poultry, eggs, fish, fruits, vegetables and dry

 

fruits.

 

Ozone gas is a naturally occurring tri-atomic form of oxygen that is formed as sunlight passes through the atmosphere. It can be generated artificially by passing high voltage electricity through oxygenated air.

 

Because ozone is an unstable, highly reactive form of oxygen, it is 51 times as powerful as chlorine, the oxidizer most commonly used by most food processors, and 3,000 times as fast at killing bacteria and other microbes.

 

While chlorine has traditionally been the sanitizer of choice in the food processing industry, there is a growing concern about such byproducts as trihalomethanes or dioxins produced when chlorine reacts with organic matter in the water. The substances are known carcinogens and are regulated in drinking water.

 

The possibility of replacing chlorine is attractive for industries seeking to reduce chemical use and eliminate the generation of chlorinated wastes