Kansas State Tests Post-Process Pasteurization System

A stainless steel tower about 12-ft tall with billows of steam blowing out the sides may be an answer for companies trying to maintain the safety of their processed meats.

The pasteurization unit at Kansas State University sits in a sterile room held to the same environmental standards as a surgical operating facility. But in this room, the goal is to keep harmful bacteria out of cooked and ready-to-eat meats that have already been packaged.

James Marsden, a Food Safety Consortium researcher at KSU, explained that the problem processing plants face is that ready-to-eat meats could become recontaminated on the surface after cooking before the final packaging procedures. Processors use thermal processing procedures to eliminate pathogens during the cooking process. The snag can come when it's time for packaging and a piece of meat that has already been cooked to control pathogenic bacteria can become recontaminated.

"Processed, ready-to-eat meat and poultry products are usually fully cooked and food safety concerns for these products result from recontamination of the product surface with the pathogen Listeria monocytogenes after cooking, but before packaging," said Curtis Kastner, the FSC program director at Kansas State.

Kansas State worked with Stork RMS Protecon Corp. of Gainesville, GA, and Steris Corp. of Menton, OH, to develop a steam pasteurization unit that can eliminate any recontamination that has occurred during packaging. They also collaborated to build the clean-room environment necessary for the unit's success.

"Through the application of post-process pasteurization, contamination of the surface of processed meat products can be virtually eliminated," Kastner said. "For sliced processed products, Stork's post-process pasteurization technology is combined with Steris' clean-room technology that results in a product that is pasteurized and then sliced and packaged in an aseptic environment, preventing recontamination."

Kansas State researchers test the unit by placing a wrapped and packaged portion of cooked ready-to-eat meat in the unit. The scientists try varying levels of exposure time and temperature to determine what combination will work most efficiently to penetrate the wrapping and kill any pathogens on the surface of the meat.

"Since post-process contamination is limited to the outer surface of processed meats, the combination of these technologies should effectively control Listeria monocytogenes and other foodborne pathogens," Marsden said. "This approach, which involves thermal processing, may be an alternative to irradiation for improving the safety of hams, hot dogs, roast beef and other processed meat products."

Irradiation is not currently authorized by federal regulators for applicaton to ready-to-eat meats. A petition is pending that seeks government approval of the process for ready-to-eat meats, but it could be months to years before any approval may be granted.

The Stork unit is a new condensing steam pasteurization technology developed in conjunction with Steris' design of the clean-room environment. The combination makes it probable that the surface of food will not become recontaminated while a pasteurized product is being packaged.

With Kansas State testing the unit, scientists will be able to evaluate more accurately the microbiological effects of condensed steam pasteurization on ready-to-eat meats, said Bill R. Sanford, chairman of Steris.

"This integrated solutions approach combines the sue of products and technologies for monitoring, reducing and preventing potential contamination at all stages throughout the food production process," Sanford said. "The ability to control microbiological contamination in the air, on hard surfaces or on the hands of workers is critical to providing food that is contamination-free."

This article is reprinted with permission from The Food Safety Consortium Newsletter, Vol. 10, No. 2, Spring 2000.

For more information contact The Food Safety Consortium, 110 Agriculture Bldg., University of Arkansas, Fayetteville, AR 72701. Tel: 501-575-5647.

Edited by Pam Ahlberg