Purpose: This study validated the efficacy of increasing concentrations of a peracetic acid applied as a spray (PAA; Microtox Plus, ZEE Company) prior to chilled subprimal packaging for reducing populations of STEC. Impact on raw beef color was documented.
Methods: Ten beef strip loins were inoculated to ca. 5 log CFU/cm2 with a 7-serogroup (O157:H7, O26, O45, O103, O111, O121, O145) cocktail of rifampicin-resistant STEC. After 30-min attachment, subprimals were sprayed with PAA at increasing concentrations from 200–1800 ppm (at 200 ppm intervals) or a water control (0 ppm) before being vacuum packaged and stored for 24 h at 4°C. Excised tissue samples were taken from the top and bottom of each subprimal and microbiologically analyzed to quantify STEC reductions and L, a*, and b* color measurements were taken from the sides of the subprimals at three sampling points: post-inoculation, 5 min post-PAA spray, and post-24 h vacuum packaged chilling.
Results: Post-PAA treatments, STEC populations decreased by 0.5–1.3 log CFU/cm2 across all concentrations, which were different (P ≤ 0.05) than the water control (0.1 log CFU/cm2 reduction). No differences (P > 0.05) were observed among application of concentrations between 400–800 ppm. STEC populations did not change (P > 0.05) in the PAA-treated subprimals after 24 h of chilled vacuum packaged storage. Although subprimal color changed over time, no difference (P > 0.05) was seen in color readings among PAA treatments of increasing concentrations.
Significance: These data suggest that a wide range of peracetic acid concentrations (≥ 400 ppm) will significantly reduce STEC on chilled beef subprimals, while having no effect on raw product color.