Effectiveness of a Commercial Lactic Acid Bacteria Intervention Applied to Inhibit Shiga Toxin-Producing Escherichia coli on Refrigerated Vacuum-Aged Beef

Table 2

Least squares means of bacterial populations on beef strip loins (log₁₀ CFU/cm²) treated with lab and vacuum aged at 4°C.

Target organisms	Experimental process stage					value
	Postinoculation	Postchilling	Posttreatment	14 days of aging	28 days of aging
Control	6.7A	6.6A	—	6.6A	6.3A	0.4047
STEC	—	7.2A	6.8B	7.1AB	6.7B	0.0151
Lactic acid bacteria (LAB)	—	—	6.5A	6.2B	6.1B	0.0124

Values are least square means from two replications with triplicate samples in each replication (). Means within a row lacking the same capitalized letter (A, B) differ at by Tukey’s Honestly Significant Differences (HSD) multiple comparisons test. Control indicates STEC counts from STEC-inoculated, nontreated beef strip loins. STEC were enumerated on tryptic soy agar supplemented with 100.0 μg/ml (TSAR) following 48 h incubation at 35°C. STEC denotes STEC means from strip loins treated with the LAB intervention by pressurized spray or ESS. STEC were enumerated on tryptic soy agar supplemented with 100.0 μg/ml (TSAR) following 48 h incubation at 35°C. Significant differences in STEC counts were not detected as a function of intervention application by pressurized spray versus ESS; counts of organisms are therefore compiled for both application methods; LAB denotes numbers of LAB enumerated from intervention-treated strip loins (pressurized spray, ESS). As significant differences in LAB counts were not detected as a function of intervention application by pressurized spray versus ESS, counts of organisms were compiled for both application methods. LAB from the biopreservative LactiGuard LAB were enumerated on de Man, Rogosa, and Sharpe (MRS) agar supplemented with streptomycin sulfate (40 μg/ml), sodium oxacillin (0.4 μg/ml), and gentamycin sulfate (5 μg/ml), as per manufacturer guidance.