Antimicrobial treatments will become a way of life for processors-if USDA has its way
by Ken Krizner, senior editor
Many possibilities exist for contamination. Even animals raised in a clean environment can become contaminated during transport, holding, or processing after slaughter.
To counteract these possibilities, USDA wants slaughtering plants to apply at least one antimicrobial treatment to carcasses before chilling or cooling. The proposal is part of USDA's inspection reform measure introduced in January.
Recent studies by the National Live Stock and Meat Board and AMI have showed that using sprays is the answer to reducing microbes on carcasses.
The industry wants rinses and sprays to replace knife-trimming to remove visible contaminants from carcasses. USDA is moving in that direction, albeit slower than what the meat industry wishes.
USDA has recently approved spray chills to cool beef carcasses, even if an Acceptable Quality Level check fails because of visible contamination.
"Because temperature is a primary factor affecting bacterial multiplication, any lots failing beef carcass [quality levels] should continue through the chilling cycle," states the revised policy, which took affect in March. "Rejected lots must be identified, reworked and pass re-inspection prior to fabrication or shipping. Any of the three samples examined on a [quality check] with milk, fecal or ingesta contamination should be trimmed immediately."
Previously, plants failing quality checks because of visible contamination could not use spray chills.
Here is a look at some of the treatments that may eventually be a permanent tool in the slaughtering plant:
Steam vacuum system: The patented process, which was approved for commercial test trials by USDA in March, involves a hot water spray in a vacuum nozzle, with steam sprayed above and below the vacuum head.
Gauges monitor water temperature and vacuum pressure, and the hot water must be maintained at 180 degrees F. Hot water sprayed on a carcass kills some bacteria and loosens contamination such as ingesta or feces, which is then vacuumed off.
Steam vacuum must occur in the pre-evisceration phase of slaughter, and can be used only if a plant is operating under a documented quality control program designed to minimize the occurrence of contamination.
Steam vacuuming must be followed up with knife trimming if visible contamination remains.
USDA based its approval for trial tests on data submitted by Dakota City, Neb.-based IBP Inc., and collected in tests conducted by the department's Agricultural Research Service's Animal Research Center in Clay Center, Neb.
"The data supports the hypothesis that under certain conditions, visible contaminants and associated bacteria can be removed at least as effectively by steam vacuuming as knife trimming," notes Michael R. Taylor, USDA undersecretary for food safety. "This technology now needs to be tested thoroughly under actual conditions."
The initial trial will be conducted in IBP-owned beef slaughter plants. At press time, Minneapolis-based Excel Corp. and Greeley, Colo.-based Monfort Inc. each were near an agreement with USDA to test the process.
Bacteria trial samples will be collected at the sites of both vacuuming and trimming procedures to compare differences in effectiveness.
Organic acid spray: Research at Colorado State University has shown that both salmonella and listeria can be controlled in beef and pork by rinsing whole carcasses with a solution of organic acid and water.
However, a study conducted for the Canadian beef industry found that organic acid spray is limited in its ability to control pathogens. The study found spoilage bacteria were found to be more sensitive to the acid treatment than were pathogens. The efficiency of the treatment depended largely on the amount of bacteria present.
Trisodium phosphate: For two years, trisodium phosphate has been used to reduce the incidence of poultry contamination. It has been suggested for beef and pork, and was mentioned by name in USDA's food safety proposal as one way of combating contamination. But beef and pork processors say further studies are needed before they can seek approval from USDA.
Hyperpasteurization: This is a relatively new technology that uses oxygen to prevent microbial contamination.
Hyperpasteurization would be an alternative to heat pasteurization and irradiation.
The process uses high vacuum to remove most of the interstitial air trapped in a food product, followed by saturating the food with pressurized oxygen, which is then removed by vacuum once more. Finally, an inert atmosphere is introduced in the processing chamber.
Early studies by FDA indicate that hyperpasteurization has produced bacteria-free pork, beef and chicken.
Electrical stimulation: Researchers are attempting to reduce the incidence of salmonella through this method. The killing effects indicate that the technique might be useful to kill bacteria during processing, preventing cross-contamination. However, electrical stimulation is not yet practical.