Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2000
Publication Date: N/A
Interpretive Summary: Plant extracts are known to kill pathogenic bacteria in test tubes, yet few studies have addressed the effect of these extracts against pathogens on meats. Several experiments were conducted to determine if two commercially available herb extracts could kill Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on beef. In the first experiment, the pathogens were not killed immediately after spraying the extracts on meat, but residual activity resulted in killing after refrigerated storage for 7 days. In the second experiment, the extracts were added to cubed beef, which was then processed into ground beef, packaged, and stored for 14 days under refrigerated storage. Pathogens were not killed substantially (less than 50%) by the extracts under these conditions. In the third experiment, beef tissues were sprayed with the extracts, vacuum packaged, and stored up to 35 days under refrigerated conditions. Treatments with herb extracts killed more than 50% of E. coli O157:H7, S. Typhimurium, and L. monocytogenes on the beef. Based on these experiments, the use of herb extracts may kill foodborne pathogens on beef when stored under refrigerated or vacuum packaged conditions. However, the antimicrobial activity of the extracts may be diminished in ground beef by the presence of fat.
Technical Abstract: The effects of plant extracts against pathogenic bacteria are well known, yet few studies have addressed the effects of these compounds against pathogens on meats. A series of experiments was conducted to determine the effectiveness of two commercially available herb extracts (Protecta One and Protecta Two) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes associated with beef. In the first experiment, pathogen populations were not affected by immediate application (day 0) of the herbal extracts; after 7 days of storage at 4 deg C, pathogens and aerobic plate counts (APC) were reduced by both extracts. In the second experiment, Protecta Two was added to beef trim inoculated with the pathogens, processed into ground beef, packaged, and remaining populations in the ground beef determined up to 14 days of 4 deg C storage. Regardless of treatment, pathogen and aerobic populations in the ground beef were not reduced substantially even after 14 days of 4 deg C storage. In the third experiment, lean or adipose beef carcass tissues were subjected to surface spray treatments with lactic acid or the herb extracts, vacuum packaged, and stored up to 35 days at 4 deg C. Treatments with herb extracts and lactic acid immediately reduced E. coli O157:H7, S. Typhimurium, and L. monocytogenes on lean and adipose surfaces and after 35 days of vacuum packaged storage at 4 deg C. The use of herb extracts may afford some reductions of pathogens on beef surfaces stored under vacuum packaged conditions at 4 deg C, as well as some limited activity against pathogens in ground product. However, the antimicrobial activity may be diminished in ground beef by the presence of adipose components.