Because of their antagonistic activity towards pathogenic and spoilage bacteria, some members of the lactic acid bacteria (LAB) have been evaluated for use as food biopreservatives. The objectives of this study were to assess the antimicrobial utility of a commercial LAB intervention against O157 and non-O157 Shiga-toxigenic E. coli (STEC) on intact beef strip loins during refrigerated vacuum aging and determine intervention efficacy as a function of mode of intervention application. Prerigor strip loins were inoculated with a cocktail (8.9 ± 0.1 log10 CFU/ml) of rifampicin-resistant (100.0 μg/ml; RifR) O157 and non-O157 STEC. Inoculated loins were chilled to ≤4°C and treated with 8.7 ± 0.1 log10 CFU/ml LAB intervention using either a pressurized tank air sprayer (conventional application) or air-assisted electrostatic sprayer (ESS). Surviving STEC were enumerated on tryptic soy agar supplemented with 100.0 μg/ml rifampicin (TSAR) to determine STEC inhibition as a function of intervention application method (conventional, ESS) and refrigerated aging period (14, 28 days). Intervention application reduced STEC by 0.4 log10 CFU/cm2 (p < 0.05), although application method did not impact STEC reductions (p > 0.05). Data indicate that the LAB biopreservative may assist beef safety protection when utilized within a multi-intervention beef harvest, fabrication, and aging process.

The purpose of this study was to compare the efficacy of different antimicrobial interventions applied via either conventional spray (CS) or handheld electrostatic spray (ESS) to reduce Shiga toxin–producing Escherichia coli (STEC) on fresh beef surfaces. Hot-boned outside rounds (ORs) were inoculated within 1 h after harvest with a cocktail of eight isolates consisting of 8 O157 and non-O157 serogroups of STEC (STEC8). ORs were hung on sterile meat hooks at 4°C for 36 h to simulate a contaminated full carcass side in the chiller. ORs were then treated with lactic acid (LA; 4.5%, w/v), 3.0% lauric arginate ester (LAE), 0.8% cetylpyridinium chloride, 200 mg/L peracetic acid, 3 mg/L chlorine dioxide, 5 mg/L ClO2, or tap water by using CS or ESS. Temperatures of LA and peracetic acid were set at 55 and 42°C before spraying, whereas all other solutions were applied at room temperature (25°C). Pretreatment and posttreatment STEC8-inoculated beef tissue samples were aseptically collected to evaluate the efficacy of interventions by application method (CS or ESS). LA applied with CS achieved the greatest reduction in STEC8 numbers (3.3 log CFU/cm2) compared with all other treatments: 0.2 log CFU/cm2 (tap water) to 2.3 log CFU/cm2 (LAE). Only for LA did a significant difference arise in mean STEC8 reductions between CS and ESS applications (3.2 versus 1.7 log CFU/cm2, respectively). Among the treatments applied with ESS, LAE produced the greatest reduction of STEC8. Antimicrobial interventions applied via conventional wand or cabinet-applied technologies can reduce the O157 and non-O157 STEC on fresh beef carcass surfaces, reducing transmission to beef consumers. HIGHLIGHTS