Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/6/2006
Publication Date: 2/1/2007
Citation: Bosilevac, J.M., Guerini, M.N., Harhay, D.M., Arthur, T.M., Koohmaraie, M. 2007. Microbiological characterization of imported and domestic boneless beef trim used for ground beef. Journal of Food Protection 70(2):440-449. Interpretive Summary: The United States must import lean boneless beef trim from countries such as Australia, New Zealand, and Uruguay in order to meet consumer demand for ground beef. The sources and incidence of foodborne diseases differ between many foreign countries and the United States. For example, in the United States, E. coli O157:H7 causes severe disease outbreaks, whereas in Australia and New Zealand non-O157 serotypes of E. coli cause similar disease outbreaks, and the rate of Campylobacter infection is six times higher in Australia than in the United States. When foreign beef trim arrives in the United States it is tested for the same bacteria as is domestic beef trim. Therefore foreign disease-causing E. coli may not be detected, and other pathogens such as Campylobacter or Salmonella may be present at much higher levels, but the United States does not currently test for them. The objective of this project was to determine whether the microbiological quality of beef trim imported from Australia, New Zealand, and Uruguay was different from that of domestic beef trim. We first tested the imported and domestic beef trim for bacteria that would indicate the general level of hygiene for the product. These tests showed that there were differences between all countries, with the best hygiene in samples from Australia and the worst hygiene in samples from Uruguay. Only minor differences among countries were detected in the prevalence of disease-causing pathogens.
Technical Abstract: The United States imports lean boneless beef trim from Australia (AUS), New Zealand (NZL), and Uruguay (URY) to meet demand for ground beef production. The reported incidence of, and etiological agents responsible for, foodborne disease differ between these countries and the United States. Therefore, our objective was to determine if current United States microbiological profiling adequately addresses the potential differences in the foreign and domestic beef trim. To determine this, we compared the hygienic status of imported and domestic (USA) beef trim by enumeration of aerobic bacteria, Enterobacteriaceae, coliforms, Escherichia coli and Staphylococcus aureus. We also compared the prevalence of pathogens between imported and domestic samples by screening for the presence of Salmonella, Campylobacter spp., Listeria spp., and non-O157 Shiga toxin-producing Escherichia coli (STEC). A total of 1,186 samples (487 USA, 220 AUS, 223 NZL, and 256 URY) of boneless beef trim were analyzed. Results of enumeration showed significant differences between samples from all countries with the lowest levels observed in samples from AUS and the highest levels in samples from URY. Six Salmonella isolates (1 NZL, 1 URY, and 4 USA), 79 Listeria monocytogenes isolates (4 AUS, 5 NZL, 53 URY, and 17 USA), and 7 Campylobacter isolates (1 NZL, 1 URY, 5 USA) were found among the trim samples profiled. Non-O157 STEC prevalence was 10% in NZL samples and about 30% in all of the other samples, with 99 STEC isolated. Serotyping of these isolates showed that hemolytic uremic syndrome-associated serotypes were not different in prevalence between imported and domestic beef trim. It may be tempting to do so, but this data cannot be used to compare the microbiological quality of beef trim between the countries examined. It is intended to show that the current pathogen monitoring procedures in the United States do not need to be changed for imported beef trim.