A team effort by university researchers and two companies has resulted in
application of a more efficient way to use the massive amounts of water
required to process turkeys. The new system uses ozone, a highly reactive
form of oxygen, to recycle water in the plants.
The Cargill, Inc., Honeysuckle White turkey processing plant in Springdale, Ark., is the site of the procedure that has been developed with Food Safety Consortium researchers at the University of Arkansas and engineers at American Water Purification, Inc., of Wichita, Kan. Water is used to chill turkey carcasses at the plants. Chill water quickly lowers the body temperature of processed turkeys, so quickly that microorganisms have limited opportunities to grow.
One gallon of water is required to process each turkey going through the chill water processing. With turkeys going through the process all day long and new water replacing the water that is discharged after chilling, a turkey plant can use a tremendous amount of water.
Recycling the water obviously saves water. In addition, the system allows the user to save on energy, sewer and pretreatment costs, explained Mark Baldwin of AWPI. When the water makes its first entry into the system, it must be chilled to 34 degrees Fahrenheit. Depending on the outdoor air temperature, the water temperature could initially be from the lower 50s to the 70s, thus requiring a major expenditure of energy to cool the incoming water. Recycled water has already gone through the initial major cooling process and needs only to be reduced by a couple of degrees as it makes subsequent trips through the process.
Once a supply of water has been used, it passes through a mechanical pretreatment and then four ozonation cylinders. Ozone gas is pumped into the cylinders to further clarify the water and kill microorganisms. Ozone kills bacteria 3,000 times faster than chlorine. Depending upon the quality of incoming water, the processors adjust the amount of ozone to maximize bacterial destruction, Baldwin said.
AWPI personnel and UA Food Safety Consortium researchers Amy Waldroup and Richard Forsythe conducted tests of the system to determine what level of ozone usage would be most efficient. The ozone generator used in the unit creates ozone at just the rate needed. The process immediately uses up the ozone so that there is only about 3 grams in existence at any given moment.
Current Food and Drug Administration rules do not yet allow ozone to come in contact with poultry products. The system strips out any residual ozone in the water prior to returning it to the chiller. The system also prevents ozone from leaking into the atmosphere. Residual ozone is captured and run through a catalytic destruction unit and turned back into oxygen.
Waldroup said the UA finished microbiology tests in late March after preparing its third set of data and that all necessary federal approvalî process have been granted. Implementation of the process enables Cargill to recycle at least 80 percent of their chill water.
Researchers are also exploring another use of ozone in the food safety process. The current rules allow application of ozone only when the water passes through the cylinders but not in the chiller tanks where the poultry is being cooled. Studies by Waldroup and Forsythe 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 Food and Drug Administration has not approved direct application of ozone to poultry, but AWPI has received permission from the agency to begin work on testing the procedure.
"Direct application of ozone in the future is something that's going to be very big," Baldwin said. "They're using it in Canada and Australia right now. We're going to be in the process of setting up some test sites for that."
The direct application process would do away with the need to use chlorine in the chillers. Canada prohibits the import of products treated with chlorine. "Even before the direct application process become commercially available, we are having a beneficial effect on the chiller with our recycling process because it allows the operator to turn the water at a higher rate than mandated minimums," Baldwin noted.