Food Safety Through Purging Pathogens
July 1, 2010 Citrus waste has long been put out to pasture as a feed supplement for cattle, but scientists now believe there is a potential hidden benefit to the practice. Dr. Todd Callaway, research microbiologist with USDA’s Agricultural Research Service, has been studying how citrus oils might help reduce pathogens and improve food safety.
Salmonella and E. coli O157:H7 are foodborne pathogenic bacteria found in the intestinal tract of cattle. The levels of these pathogenic bacteria in the gut of cattle are highly variable and change a great deal based on season of the year. By reducing the level of pathogenic bacteria in food animals entering the slaughter or processing plant, the steps taken in post-slaughter pathogen reduction can be even more effective at improving food safety.
Antibacterial Peel
The overall goal of this project, jointly funded by the National Cattlemen’s Beef Association and USDA, is to develop methods to reduce pathogens in food animals before slaughter. And based on what scientists have found, it appears the by-product of orange peel production could provide an economically feasible, “green” pre-harvest intervention strategy and also create a value-added by-product for citrus. “Orange peel contains essential oils (e.g., limonene) that are antibacterial,” Callaway says. “So, we undertook studies to see if the antibacterial activity of orange peel carried over into the gut environment.”
Appealing Results
In early test-tube type studies simulating the gut, orange peel and pulp worked to reduce E. coli O157:H7 and Salmonella. “In the currently reported studies, we examined the effect of feeding dried orange peel on artificially inoculated Salmonella populations in sheep (as a model of cattle),” Callaway says. “The results were a 10-fold reduction in Salmonella in the sheep’s rumen cecum and rectum. Inoculated E. coli O157:H7 populations throughout the gut of sheep were reduced most effectively by 10% orange peel in the diet, but 5% in the diet was still somewhat effective.”