Purpose: Evaluate the efficacy of an air-assisted electrostatic spraying system (ESS) and/or the Sprayed Lethality in Container (SLIC®) method to deliver antimicrobials on surface of beef subprimals to reduce levels of Shiga Toxin-producing Escherichia coli (STEC).
Methods: Beef subprimals were surface inoculated (lean side; ca. 5.5 log CFU/subprimal) with a cocktail comprised of single strains of STEC (STEC-8; O111:H, O45:H2, O103:H2, O104:H4, O121:H19, O145:NM, O26:H11, and O157:H7). Inoculated subprimals were then surface treated with lauric arginate (LAE; 50 ppm), peroxyacetic acid (PAA; 400 ppm), or cetylpyridinium chloride (CPC; 400 ppm) by passing each subprimal through an ESS cabinet or via SLIC. Next, subprimals were vacuum-packaged and stored at 4°C for up to 7 days. One set of subprimals was sampled after 2 h of storage, whereas the other set, was retreated with the above antimicrobials via SLIC after 3 days of storage and then sampled after 2 h or 4 days of additional storage at 4°C.
Results: Single/initial application of LAE, PAA, or CPC via ESS or SLIC resulted in reductions of ca. 0.6 to 2.0 log CFU/subprimals over 7 days of storage at 4°C. However, when subprimals were initially treated with LAE, PAA, or CPC via ESS or SLIC and then retreated with the same antimicrobials via SLIC on day 3, additional reductions of 0.1 to 1.6 log CFU/subprimals in pathogen numbers were observed after an additional 4 days of storage at 4°C.
Significance: Application of LAE, PAA, or CPC, alone or in combination, via ESS or SLIC is effective for reducing low levels of STEC on the surface of beef subprimals.