Study Reveals Carcass Spray Superiority Over Hand-Trimming in Reducing Risk
Evidence from a Colorado State University study indicates that sprays and rinses are more effective than hand-trimming at reducing microbial counts and removing visible foreign material from animal carcasses.
Colorado State's three-phase study compared spray-washing vs. hand-trimming, examined hot water and chemical interventions, and conducted field trials of variables for spray-washing.
Project funding came from Greeley, Colo.-based ConAgra Red Meat Cos. and the National Live Stock & Meat Board.
The study found that:
-- Trimmers miss visible contaminants and cannot see bacteria, and workers can't trim what they can't or don't see.
-- Spray-washing reduces contaminants and bacteria. Properly adjusted spray-washing systems do not have to see contaminants to remove them.
Phase I
Researchers compared hand-trimming with spray-washing vs. spray-washing without hand-trimming of beef brisket samples on bacteria counts and visual fecal scores.
Initial results revealed that there was little difference between the two methods in reducing microbiological contamination.
There was also a comparison of the effects of water pressure (40, 200, 300 and 400 pounds PSI) during spray-washing on bacteria counts and visual fecal scores on beef brisket samples. Spray-washing at higher rates of pressure, if done properly, best reduces bacteria counts and fecal material.
Phase II
Researchers concluded that the best combination of interventions for reducing bacteria counts on beef brisket samples is a 165 degree F water spray at 300 PSI in the first wash, followed by a spray-wash with hydrogen peroxide.
This phase of the study compared five chemical sanitizers and hot water on total plate count, streptomycin-resistant bacteria count, and visual fecal score on beef brisket samples.
Results showed that trisodium phosphate, ozone and hydrogen peroxide reduced bacteria counts more successfully than other chemical sanitizers, including acetic and phosphoric acids.
In addition, research concluded that spray-washing, when done properly, does not spread contamination.
Phase III
Results revealed that compared to no trim and no wash, every combination of washing-with or without trimming, with or without chemical agents-lowered aerobic plate counts and E. coli counts on beef carcass surfaces.
Compared to the treatment that combined trimming with hot water washing, washing without trimming achieved similar reductions in aerobic plate counts and E. coli counts.
Hot water washing without trimming, based on comparative standard deviations, achieved more consistent lowering of aerobic plate counts and of E. coli counts than did trimming plus washing.
More ammo for industry
Carcass washing is one of the packing industry's leading solutions to sanitizing meat. The chemicals are able to control microbial contamination and may preserve characteristics, such as color and flavor.
In 1993, only five U.S. meat plants were using carcass sprays. Today, that figure is up to nearly 30.
The Colorado State study is the latest ammunition in the meat industry's arsenal as it continues lobbying efforts with USDA to allow the use of more sprays and rinses.
USDA is responding. It eliminated prior approval on certain antimicrobial rinses and hot water rinses on carcasses in November, and its inspection reform proposal wants carcasses to be exposed to at least one antimicrobial rinse before entering the chiller.
Processors hope the Colorado State study can further convince USDA of the potential for carcass washes and sprays, rather than enforcement of the zero-tolerance policy for fecal contamination.
"The only way to convince [USDA] that carcass sprays are more effective than hand-trimming is to give them solid, scientific evidence," says an executive, whose meat processing company is lobbying the department to allow more uses for carcass sprays.
Gary Smith, professor of animal science at Colorado State University and one of the study's authors, agrees.
"The meat industry has taken steps to develop slaughtering and dressing systems that reduce contamination," he notes. "Several studies have confirmed the effectiveness of spray-washing treatments in reducing microbial counts and removing visible foreign material from carcasses."