Dennis E. Burson
Date of this Version
McCarty, K. A. 2016. Antimicrobial Interventions Applied to Beef Sub-Primals for the Control of Escherchia coli and Their Impact on Ground Beef Quality. University of Nebraska-Lincoln Thesis.
Due to their severe health implications, seven shiga toxin-producing E. coli (STEC) serotypes were declared adulterants by USDA-FSIS in raw, non-intact beef products. Small business beef processing facilities are being asked to implement an intervention on the beef sub-primals and trim they receive for ground beef production. This study evaluates the efficacy of reducing rifampicin-resistant E. coli (E. coliRif) using 4.5% lactic acid (LA), 2.5% Beefxide™ (BX), and 380 ppm peroxyacetic acid (PAA) when applied by dip, spray or electrostatic spray (ESS) to the mostly fat lateral surface and mostly lean medial surface of beef shoulder clods (IMPS 114) and compared to an inoculated control on reducing the presence of E. coliRif on beef sub-primals meant for ground beef. All organic acid treatments had a greater reduction (P < 0.01) than the inoculated control using E. coli petrifilm. However, when using APC petrifilm, all ESS treatments were similar (P > 0.05) to the control. In addition, LA had greater (P < 0.05) E. coliRif reductions on E. coli petrifilm than BX treatments. PAA had greater (P < 0.05) E. coliRifreductions using APC petrifilms than BX. Ground beef samples from electrostatic spray treatments had similar reductions (P > 0.05) to that of the inoculated control and had lower reductions (P < 0.001) than the dip or spray methods. A second study was designed to determine the effects of the same acids and application methods on ground beef quality. Ground beef samples from the PAA spray were darker (P < 0.05) than the control, PAA dip and electrostatic spray, BX spray and electrostatic spray, and LA spray. In addition, LA electrostatic spray was less yellow (P < 0.01) than the control and BX dip and spray treatments. When looking at APC counts, LA electrostatic spray had higher CFU/g than PAA spray and dip, BX spray and electrostatic spray, and LA dip. TBARS values showed that LA treatments had greater (P < 0.01) oxidation than PAA treatments. LA dip and electrostatic and BX spray had lower (P < 0.001) pH values compared to the control. All treatments reduced E. coliRif counts and had minimal effects on quality attributes.
Advisor: Dennis E. Burson