Paracetic Acid Washes Reduce Salmonella Load on the Surface of In-shell Pecans and Prevents Cross-Contamination Between Pecans During Conditioning

Authors: Bardsley, Cameron; Chasteen, Kaicie; Sherman, Samantha; ARTHUR, VERA - Fort Valley State University; MAHAPATRA, AJIT - Fort Valley State University; NIEMIRA, BRENDAN - US Department Of Agriculture (USDA); Shapiro Ilan, David

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2025
Publication Date: 2/24/2025
Citation: Bardsley, C.A., Chasteen, K.S., Sherman, S.H., Arthur, V., Mahapatra, A.K., Niemira, B.A., Shapiro Ilan, D.I. 2025. Paracetic Acid Washes Reduce Salmonella Load on the Surface of In-shell Pecans and Prevents Cross-Contamination Between Pecans During Conditioning. Food Control. 111248. https://doi.org/10.1016/j.foodcont.2025.111248.
DOI: https://doi.org/10.1016/j.foodcont.2025.111248

Interpretive Summary: Once pecans are harvested they are often washed and/or go through a conditioning step, if the water isn't treated it could become contaminated with pathogens which could spread to other in-shell pecans. Often a chlorine-based sanitizer is used to avoid contamination. Chlorine-based sanitizers have many negative drawbacks. Using an alternative sanitizer, such as peracetic acid, may be as effective as chlorine and not have the negative attributes. In this study peracetic acid at varying concentrations and sodium hypochlorite were added to water and tested against water containing no antimicrobial treatments for 2, 15, 60, and 240 minutes to treat Salmonella contaminated pecans. Peracetic acid at 90 ppm concentration was found to be the most effective concentration and reduced Salmonella by as much as 99.99%. Peracetic acid at a lower concentration was just as effective as sodium hypochlorite at reducing Salmonella and preventing contamination. Peracetic acid can be an effective alternative to chlorine-based sanitizers to reduce Salmonella populations and prevent cross-contamination on in-shell pecans during conditioning.

Technical Abstract: In-shell pecans are generally conditioned in water prior to shelling which presents the potential for foodborne pathogen cross-contamination. The use of sanitizers in conditioning water can be an effective way to prevent cross-contamination. The objectives of this study were to determine the effectiveness of varying concentrations of peracetic acid (PAA) in conditioning water at reducing Salmonella loads and preventing cross-contamination on in-shell pecans compared to sodium hypochlorite (NaOCl). In-shell pecans were inoculated with two concentrations (high and low) of a rifampicin resistant five-strain Salmonella cocktail. Inoculated pecans and uninoculated pecans were placed in water treatments (PAA: 0, 30, and 90 ppm; NaOCl: 1000 ppm free chlorine) and were sampled at 0, 2, 15, 60, and 240 min. There were significant (P<0.05) Salmonella reductions at each timepoint on pecans conditioned in water containing 30 and 90 ppm PAA with the final reduction being 3.4±0.9 and 4.2±0.5 log CFU/g, respectively, after 60 min. The 90 ppm PAA treatment was significantly more effective at preventing Salmonella cross-contamination compared to the 0 and 30 ppm PAA treatments. Up to 4.0 log CFU/g transfer of Salmonella was observed from inoculated to uninoculated pecans in the 0 ppm treatment. Both 90 ppm PAA and 1000 ppm NaOCl treatments were found effective at reducing Salmonella levels (4.2±1.2 and 4.0±1.4 log CFU/g, respectively) and preventing cross-contamination over a four-hour conditioning period. The PAA was found to be an effective sanitizer compared to NaOCl at preventing cross-contamination and also reducing Salmonella populations on in-shell pecans during washing and conditioning.