**3. Results**

### *3.1. Untreated Chicken Wings*

Aerobic microbial populations of the uninoculated and untreated chicken wings used for the study ranged from 2.6 to 4.3 log CFU/mL, with a mean of 3.6 ± 0.7 log CFU/mL. Naturally occurring *Campylobacter* populations were not detected (<1 CFU/mL) in five of the six uninoculated and untreated wings analyzed, while the remaining sample had a *Campylobacter* count of 1 CFU/mL. As such, bacterial populations recovered with the mCCA **Table 3.** Mean (*n* = 6)

culture medium from inoculated control (untreated) and treated samples (Tables 2 and 3) were those of the inoculum strains.

**Table 2.** Mean (*n* = 6) *Campylobacter jejuni* populations (log colony-forming units [CFU]/mL ± standard deviation [SD]) for inoculated (six-strain mixture; 3 to 4 log CFU/mL) chicken wings that were left untreated (control) or were immersion-treated (5 s, 500 mL of solution per sample) with various treatment solutions.


SSS: sulfuric acid and sodium sulfate blend; PAA: peroxyacetic acid; SSS-aPAA: PAA (550 ppm) acidified with SSS (pH 1.2); FA-aPAA: PAA (550 ppm) acidified with formic acid (1.5%). a–e Least squares means in the same column without a common superscript letter are different (*p* < 0.05). y–z Least squares means in the same row without a common superscript letter are different (*p* < 0.05). \* One of the six samples analyzed had a *C. jejuni* count that was below the microbial analysis detection limit of 1 CFU/mL; therefore, the mean is reported as < (less than) the mean.


populations

 (log

colony-forming

 units [CFU]/mL ±

*Campylobacter*

 *jejuni*


SSS: sulfuric acid and sodium sulfate blend; PAA: peroxyacetic acid; SSS-aPAA: PAA (550 ppm) acidified with SSS (pH 1.2); FA-aPAA: PAA (550 ppm) acidified with formic acid (1.5%). a–e Least squares means in the same column without a common superscript letter are different (*p* < 0.05). y–z Least squares means in the same row without a common superscript letter are different (*p* < 0.05).

Immersion and spray application methods of the test solutions were evaluated on the same experiment day; therefore, the same set of untreated inoculated samples were used as controls for both application methods (Tables 2 and 3). The inoculation level of *C. jejuni* on the wings following the inoculation procedure, as determined by microbial analysis of untreated inoculated samples, was 3.9 log CFU/mL, and similar pathogen levels were recovered from untreated wings stored aerobically at 4 ◦C for 24 h (Tables 2 and 3).

#### *3.2. Chicken Wings Treated by Immersion Application of Antimicrobial Treatments*

*C. jejuni* populations recovered from immersion-treated wings immediately after treatment (0 h) and after 24 h of refrigerated (4 ◦C) storage are shown in Table 2. Compared to the untreated control, all six immersion treatments effectively (*p* < 0.05) reduced initial (0 h) inoculated *C. jejuni* populations (3.9 log CFU/mL), with reductions ranging from 0.5 (water) to 2.2 (PAA, and SSS-aPAA) log CFU/mL. Moreover, pathogen counts recovered from wings that had been treated with any of the five tested chemical solutions were 1.2 (SSS) to 1.7 (PAA, SSS-aPAA) log CFU/mL lower (*p* < 0.05) than the pathogen counts of samples that had been treated with water. No (*p* ≥ 0.05) differences in efficacy against *C. jejuni* were observed at the 0-h sampling time between the SSS, formic acid, and FAaPAA. Additionally, formic acid, PAA, and the two acidified PAA treatments were equally (*p* ≥ 0.05) effective against *C. jejuni* immediately following their application, reducing initial populations by 1.8 (formic acid) to 2.2 (PAA, and SSS-aPAA) log CFU/mL.

Within each immersion treatment, pathogen counts of samples analyzed after the refrigerated storage period were similar (water, PAA; *p* ≥ 0.05) or lower (SSS, formic acid, SSS-aPAA, FA-aPAA; *p* < 0.05) than the counts of corresponding 0-h samples (Table 2). More specifically, at the 24-h sampling time, pathogen counts of wings that had been treated with SSS, formic acid, SSS-aPAA, or FA-aPAA were 0.6, 0.9, 0.8, and >1.2 log CFU/mL lower (*p* < 0.05), respectively, than counts of the corresponding treatments at the 0-h sampling time. Furthermore, it was observed that within the 24-h sampling point, *C. jejuni* counts of wings that had been treated with SSS-aPAA or FA-aPAA were lower (by 0.5 and >0.8 log CFU/mL, respectively; *p* < 0.05) than the counts of samples that had been treated with non-acidified PAA.

#### *3.3. Chicken Wings Treated by Spray Application of Antimicrobial Treatments*

Results for the spray-treated wings are presented in Table 3. Spray application of the treatments lowered (*p* < 0.05) initial *C. jejuni* populations (3.9 log CFU/mL) by 0.3 (water) to 1.2 (FA-aPAA) log CFU/mL. No (*p* ≥ 0.05) differences in efficacy against the pathogen were noted between the water treatment and SSS treatment. Additionally, formic acid and PAA had similar (*p* ≥ 0.05) immediate (0 h) antimicrobial effects, reducing (*p* < 0.05) initial pathogen populations by 0.7 and 0.9 log CFU/mL, respectively. At the 0-h sampling time, surviving *C. jejuni* populations of wings treated with SSS-aPAA or FA-aPAA were lower (*p* < 0.05) than those of samples treated with SSS or formic acid (by 0.6 and 0.5 log CFU/mL, respectively). No (*p* ≥ 0.05) differences in antimicrobial efficacy were obtained at 0 h between PAA and the two acidified PAA treatments.

*C. jejuni* counts recovered from wings treated with formic acid, SSS-aPAA or FA-aPAA, and stored at 4 ◦C (24 h), were 0.2, 0.4, and 0.6 log CFU/mL lower (*p* < 0.05), respectively, than the counts obtained for these treatments at the 0-h sampling time (Table 3). However, for samples that had received the water, SSS or PAA treatment, pathogen levels recovered after 24 h of storage were similar (*p* ≥ 0.05) to those obtained immediately after treatment application. Lastly, as seen for the immersion application method (Table 2), although no statistical differences (*p* ≥ 0.05) were observed between the PAA and either of the acidified PAA treatments at the 0-h sampling point, after refrigerated storage, pathogen counts of SSS-aPAA and FA-aPAA spray-treated samples were lower (by 0.4 and 0.7 log CFU/mL, respectively; *p* < 0.05) than those of wings that were spray-treated with PAA (Table 3).
