Efficacy of selected chemicals for killing pathogenic and spoilage microorganisms on chicken skin

Chicken skin inoculated with Salmonella spp. or Listeria monocytogenes was washed for 30 min with sterile water (control), 10% solutions of sodium tripolyphosphate (STPP), monosodium phosphate (MSP), sodium acid pyrophosphate (SAPP), or sodium hexametaphosphate (SHMP), 1% trisodium phosphate (TSP), 1% lactic acid or 0.05% NaOH, with or without the addition of 1% or 5% Tween 80. Viable populations of Salmonella spp., L. monocytogenes, and psychrotrophs were significantly (P<0.05) lower on skin washed with 1% TSP or 1% lactic acid compared to populations on skin washed with water or 10% MSP, STPP, SAPP or SHMP. Washing skin with 0.05% NaOH significantly reduced the Salmonella spp. population but had no effect on L. monocytogenes. The addition of 5% Tween 80 to TSP solutions enhanced the removal of psychrotrophs and Salmonella but had little effect on L. monocytogenes. Skin inoculated with Salmonella spp., L. monocytogenes, Campylobacter jejuni or Staphylococcus aureus was washed in sterile water, 0.3% lactic acid/0.05% sodium benzoate (LB35), or 0.5% lactic acid/0.05% sodium benzoate (LB55) and then stored at 4 o C for up to 16 days. Washing skin with solutions of LB35 or LB55 resulted in greater reductions in populations of Salmonella spp., L. monocytogenes, and C. jejuni compared to washing with water. No viable cells of Salmonella spp. were detected on skin washed with LB35 or LB55 and stored for 2 and 8 days at 4 o C, respectively. Populations of L. monocytogenes on control skin increased slightly after storage for 8 days but the pathogen was not detected on LB35-and LB55-washed skin after 6 days. C. jejuni was not detected on LB35- and LB55-washed skin after 2 days of storage at 4 o C, whereas S. aureus steadily decreased to a non-detectable level after 8 days