Project Summary

Pilot Study for Microbial Mapping II

Principle Investigator(s):
M.L. Kain, L.M. Ware, H.N. Zerby, R.C. Cannell, K.E. Belk, J.N. Sofos and G.C. Smith
Colorado State University
Completion Date:
March, 1998


Layman’s Summary 

A pilot study was performed to investigate the sponging vs the excising method of tissue as a means of determining microbiological counts on beef carcasses and subprimal cuts with the results and methods developed being used for a much larger study. A total of 96 beef carcasses at the packing plant, 214 subprimal cuts at the packer and retail level and 64 retail cuts at the retail store were sampled and analyzed. All samples were analyzed for total plate count (TPC), total coliform count (TCC), Escherichia coli count (ECC) and for the presence of Salmonella and Listeria. Additionally, beef carcasses were analyzed for lactic acid bacteria (LAB). The excising method recovered greater numbers of bacteria with less variation in the numbers in comparison to the sponging method. Little difference was found in microbial counts when samples were taken from either fat or muscle tissue. Microbial counts on subprimal cuts at the packing plant and retail store were very similar, suggesting that this portion of the distribution and handling process was done correctly. However, there was a substantial increase in microbial counts on beef cuts that were exhibited at the retail stores (display cases) for up to 48 hours. No Salmonella spp. were found on any carcasses or cuts. However, the presence of Listeria monocytogenes on subprimal cuts and retail cuts highlights the need for good manufacturing practices and microbial intervention strategies during the beef distribution cycle.