Purpose : The purpose of this study was to evaluate chlorine and selected organic acids for their efficacy in killing Salmonella on pecan nutmeats. The effect of applying intermittent vacuum and atmospheric pressure to inoculated nutmeats during exposure to sanitizers was studied.
Methods : Pecan pieces and halves were immersion- or surface-inoculated with a five-serotype mixture of Salmonella, dried, and stored at 4°C for 3 to 6 weeks. Nutmeats were treated with chlorine (200, 400, 1,000 µg/ml), lactic acid (0.5, 1, 2%), levulinic acid (0.5, 1, 2%), sodium dodecyl sulfate (SDS, 0.05%), lactic acid plus SDS, levulinic acid plus SDS, and a mixed peroxyacid sanitizer (Tsunami 200; 40, 80 µg/ml) for up to 20 min. Intermittent vacuum and atmospheric pressure was applied in selected tests. The number of Salmonella surviving treatment of nutmeats was determined.
Results : The addition of SDS to lactic and levulinic acid solutions resulted in generally higher reductions of Salmonella compared to reductions achieved with other sanitizers. However, regardless of type or concentration of sanitizer, treatment for up to 20 min failed to reduce the pathogen on immersion-inoculated nutmeats by more than 1.1 log CFU/g; maximum reductions on surface-inoculated pieces and halves were 0.7 - 2.6 log CFU/g and 1.2 - 3.0 log CFU/g, respectively. Intermittent vacuum and atmospheric pressure treatments did not enhance lethality.
Significance : Prevention of contamination of pecans during cracking and shelling is critical. Once nutmeats are contaminated, the effectiveness of sanitizers at concentrations tested in this study is minimal.