Numerous studies have addressed the effectiveness of various treatments (including hot water, organic acids, and other sanitizers) designed to reduce numbers of bacteria on beef carcass surfaces. These treatments have been highly effective in reducing pathogens and spoilage organisms. However, unusual spoilage patterns resulting from treatments have been described by some in the industry, including suggestions that meat becomes “too clean” with these treatments, and that pathogens might be able to grow faster due to a lack of competition.
This study focused on reproducing conditions in ground beef production that may lead to unusual spoilage patterns or pathogen growth. Half of the studies were performed using beef contaminated with pathogens that included E. coli O157:H7 and Salmonella typhimurium. Beef was treated with three sanitizers: hot water, lactic acid, and acetic acid. Ground beef was processed from this treated meat, packaged and stored at 39º and 50º F, and then sampled for bacterial levels every seven days for seven weeks. Bacteria isolated from packages of ground beef that were not inoculated with pathogens were identified to detect potential differences in spoilage patterns due to carcass decontamination treatments.
Results from this study indicate that antimicrobial treatments applied to carcasses are not likely to affect spoilage patterns in ground beef. Unusual spoilage patterns resembling those in industrial settings were only observed when packages were stored at elevated temperatures (50º F). In addition, no treatment caused an excessive outgrowth of pathogens. Bacterial type distributions were similar for all treatments, indicating no selection of bacteria due to particular treatments. Based upon these data, it is most likely that the unusual spoilage patterns reported in the industry are caused by storage in upper ranges of refrigeration temperatures.