Methods for controlling Escherichia coli O157:H7 and Salmonella surrogates during the production of non-intact beef products
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This study evaluated methods for controlling Escherichia coli O157:H7 and Salmonella non-pathogenic bacterial surrogates during the production of marinated non-intact beef products. Hot (~30 degrees C) boneless, beef strip loins (n = 54, Institutional Meat Purchase Specification 180) were inoculated with one of two levels (approximately 5.8 and 1.9 log10 CFU/cm2, hereafter referred to as high- and low-inoculated, respectively) of non-pathogenic, rifampicin-resistant E. coli organisms used to simulate harvest floor contamination. The inoculated beef strip loins were chilled at 2 degrees C for 24 h, and then vacuum packaged and aged for 7 to 24 days at 2 degrees C. The beef strip loins were subjected to one of five treatments or control (no treatment). Spray treatments were: 2.5% L-lactic acid, 5.0% L-lactic acid, 1,050 ppm acidified sodium chlorite, 205 ppm peroxyacetic acid, and tap water. Lactic acid treatments were applied at ~53 degrees C, whereas the other sprays were applied at room temperature (~25 degrees C). Treated and control pieces were tumble marinated using a commercial marinade. Sample counts were collected throughout the experiment to track reductions in inoculated microorganisms as impacted by antimicrobial treatment and processing. For the high-inoculated strip loins, the 5.0% L-lactic acid treatment was most effective (P < 0.05) across treatments and control at reducing surrogate organisms on meat surfaces before marination, producing a 2.6 log10 CFU/cm2 reduction. The water treatment accounted for the least (P < 0.05) reductions across treatments and control of surrogate organisms on the meat surface before marination. Peroxyacetic acid produced the greatest reduction of surface surrogate organisms in the finished, marinated product. The water treatment resulted in greater internalization of surrogate microorganisms when compared to the control. Furthermore, certain less effective antimicrobial sprays such as water may facilitate internalization of surface bacteria, more so than non-treated subprimals. It is important that producers of non-intact beef products focus on using effective antimicrobial sprays that maximize reductions and minimize internalization of surface bacteria into the finished product.
Ulbrich, Carson (2012). Methods for controlling Escherichia coli O157:H7 and Salmonella surrogates during the production of non-intact beef products. Master's thesis, Texas A&M University. Available electronically from