Peracetic acid washes reduce Salmonella load on the surface of in-shell pecans and prevents cross-contamination between pecans during conditioning

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 reduce 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 on pecans (4.2 ± 1.2 and 4.0 ± 1.4 log CFU/g, respectively) and preventing cross-contamination over a 4-h conditioning period. The PAA was an effective sanitizer compared to NaOCl at preventing cross-contamination and also reducing Salmonella populations on in-shell pecans during washing and conditioning.