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Comparison of Aqueous Chemical Treatments to Eliminate Salmonella on Alfalfa Seeds October 2000
Abstract This
study was undertaken to evaluate various chemical treatments for their
effectiveness in killing Salmonella on alfalfa seeds. Immersing inoculated seeds
in solutions containing 20,000 ppm free chlorine (Ca[OCl]2), 5% Na3PO4, 8% H2O2,
1% Ca(OH)2, 1% calcinated calcium, 5% lactic acid, or 5% citric acid for 10 min
resulted in reductions of 2.0 to 3.2 log10 CFU/ g. Treatment with 1,060 ppm
Tsunami or Vortex, 1,200 ppm acidified NaClO2, or 5% acetic acid were less
effective in reducing Salmonella populations. With the exceptions of 8% H2O2, 1%
Ca(OH)2, and 1% calcinated calcium that reduced populations by 3.2, 2.8, and 2.9
log10 CFU/g, respectively, none of treatments reduced the number of Salmonella
by more than 2.2 log10 CFU/g without significantly reducing the seed germination
percentage. Treatment
with 5% acetic, lactic, or citric acids substantially reduced the ability of
seeds to germinate. Treatment
with 1% Ca(OH)2 in combination with 1% Tween 80, a surfactant, enhanced
inactivation by 1.3 log10 CFU/g compared to treatment with 1% Ca(OH)2 alone. Presoaking
seeds in water, 0.1% EDTA, 1% Tween 80, or 1% Tween 80 plus 0.1% EDTA for 30 min
before treatment with water, 2,000 ppm NaOCl, or 2% lactic acid had a minimal
effect on reducing populations of
Salmonella. Results
indicate that, although several chemical treatments cause reductions in
Salmonella populations of up to 3.2 log10 CFU/g initially on alfalfa seeds when
analyzed by direct plating, no treatment eliminated the
pathogen, as evidenced by detection in enriched samples. |