Ozone Looks Better and Better for Food Processing Disinfection

Last June, a panel of experts from food science, ozone technology and other related fields granted Generally Recognized as Safe (GRAS) status for ozone use in food processing. This GRAS status allows food processors to use ozone right now in their washing, handling and packaging processes.

Recent studies on the disinfection of foods, including the use of gaseous ozone for increasing storage life and ozone dissolved in water for sanitizing surfaces of vegetables, fruits, and other agricultural products, support the position that ozone is a powerful disinfectant. Ozone has been used safely and effectively in water treatment for nine decades and has been approved in the U.S. as GRAS for treatment of bottled water since 1982. In 1975 the Food and Drug Administration (FDA) accepted the use of gaseous ozone up to 0.1 ppm in meat-aging coolers.

Jeff Barach of the National Food Processors Association comments, "Ozone is very efficient in killing pathogens and spoilage organisms and its use by the food industry will be welcomed as another tool to ensure the production of safe and wholesome foods."

Recent Applications
Cyclopss Corp. (Salt Lake City, Utah) and Schlyer Machinery Co., (Wilson, N.Y.) have announced their intent to develop and manufacture a system that could be used by food processors to kill microbial contaminates including E.coli, Listeria and Salmonella, as well as water-born microbes such as Giardia and Cryptosporidium. The system will be used initially for fruits and vegetables. The ozone system kills E.coli more than 3,000 times faster than chlorine.

"The basic system is similar to a sophisticated car wash: ozonated water is sprayed over, under and around the food at all points as a conveyor system moves the foods through," says Bill Soddard, Cyclopss' president. He adds that the reduced risk from not having to ship chlorine, and the lack of residue after the ozone treatment, are strong pluses for the technology.

BOC Gases (Murray Hill, N.J.) has introduced its SafeQuest macron loop system, which was approved by the USDA in May of this year. The system utilizes ozone to disinfect and recycle water for poultry processing, helping poultry processors meet the national standards designed to minimize incidents of contamination including salmonella and E.coli.

According to Dennis Smithyman, BOC Gases' vice president of food markets, BOC has worked closely with the Electric Power Research Institute (EPRI) to achieve the recently announced self-affirmation of GRAS status of ozone in the industries regulated by FDA and U.S. Department of Agriculture (USDA) including meat, poultry, fruits, vegetables and seafood.

The SafeQuest system is available in a variety of sizes depending on the size of the chiller bath and the organic load. A sanitary pump moves water taken from the chiller bath to a mechanical filtration device called the macron filter. Particles as small as 25 microns including organic matter, fats, oils and grease are removed from the water. The filtered water is then titrated with ozone gas, killing any pathogens. The system is engineered to process 400 gal/min or more.

The Cargill, Inc., Honeysuckle White turkey processing plant in Springdale, Ark., is the site of a procedure that has been developed with Food Safety Consortium researchers at the University of Arkansas and engineers at American Water Purification, Inc. (Wichita, Kan.).

By recycling the water used to chill turkey carcasses, the company saves water, energy, and sewer and pretreatment costs. Once a supply of water has been used, it passes through a mechanical pretreatment and then four ozonation vessels. Ozone gas is pumped into the vessels to further clarify the water and kill microorganisms. Depending upon the quality of incoming water, the processors adjust the amount of ozone to maximize bacterial destruction. The system strips out any residual ozone in the water prior to returning it to the chiller. Residual ozone is captured and run through a catalytic destruction unit and turned back into oxygen. Implementation of the process enables Cargill to recycle at least 80 percent of their chill water.

Studies have shown that direct application of ozone to poultry during immersion chilling can improve the microbiological safety of the products and can extend their shelf life during refrigerated storage. The direct application process would do away with the need to use chlorine in the chillers.

Advantages
Ozone has been shown to be more effective than chlorine in killing bacteria, fungi and viruses, and it does this at 1/10 the concentration. Ozone can be generated on site from air and electricity, and with a rather short life (only about 20 minutes), it is produced only when needed; no hazardous chemicals need to be transported. The gas does not leave any toxic by-products or residues, does not effect healthy cells or alter a food's chemistry. Ozone always reverts back to its original form of oxygen. Ozone reaction time is fast and requires much less contact time than chemical disinfectants. Ozone doesn't remain in water so there are no safety concerns about consumption.

Although ozone treatment is more expensive, improvement in ozone generators, better controls, and increasing concerns about the hazards of storing large supplies of chlorine gas in high-population areas, argue strongly for consideration of ozone as an alternative disinfectant.

For industrial applications, ozone is produced by means of an electric discharge through air or pure oxygen passing between concentric tubular electrodes. The ozone-enriched gas is then bubbled through water and the residual ozone is destroyed. The wash water, called flume water, can be filtered and recycled for reuse.

Future Ozone Applications
Proponents of the technology say that the current applications are only the beginning. Additional potential applications for ozone in the food industry include increasing the yield of certain crops, protection of raw agricultural commodities during storage and transit, sanitizing packaging materials used for food storage, and storage of meat, fruit and cheese.

Fruit and vegetable processing systems that incorporate ozone-generating technology will be able to produce cleaner food while using substantially less water. They will also reduce the amount of toxic discharges from the process, resulting in significant savings. Ozone washing technology also may have application in the treatment of meats, poultry and eggs to reduce microbial contamination.

For more information
American Water Purification, Inc., American Financial Center, 7701 E. Kellogg, Suite 670, Wichita, KS 67207. Tel: 316-685-3333; Fax: 316-685-3343.

BOC Gases, 575 Mountain Ave., Murray Hill, NJ 07974. Tel: 908-771-1512.

Cyclopss Corp., 3646 West 2100 South, Salt Lake City, Utah 84120. Tel: 801-972-9090; Fax: 801-972-9092.

By Pam Ahlberg