Reduction of Salmonella Ecoli O157 H7 by Gamma Radiation of Inoculated Sprouts

Reduction of Salmonella SPP. andStrains of Escherichia Coli O157:H7 by Gamma Radiation of Inoculated Sprouts
July 2000
Journal of Food Protection
Vol. 63, No. 7, pp. 871­875
Kathleen T. Rajkowski, Donald W. Thayer

ABSTRACT
There have been several recent outbreaks of salmonellosis and infections withEscherichia coli O157:H7 linked to the consumption of raw sprouts. Use ofionizing radiation was investigated as a means to reduce or to totallyinactivate these pathogens, if present, on the sprouts.  The radiation Dvalue, which is the amount of irradiation in kilograys for a 1-log reduction incell numbers, for these pathogens was established using a minimum of five dosesat 19 ± 1°C. Before inoculation, the sprouts were irradiated to 6 kGy toremove the background microflora. The sprouts were inoculated either withSalmonella spp. cocktails made with either meat or vegetable isolates or with E.coli O157:H7 cocktails made with either meat or vegetable isolates. Theradiation D values for the Salmonella spp. cocktails on sprouts were 0.54 and0.46 kGy, respectively, for the meat and vegetable isolates. The radiation Dvalues for the E. coli O157:H7 cocktails on sprouts were 0.34 and 0.30 kGy,respectively, for the meat and vegetable isolates. Salmonella was not detectedby enrichment culture on sprouts grown from alfalfa seeds naturally contaminatedwith Salmonella after the sprouts were irradiated to a dose of 0.5 kGy orgreater. Ionizing radiation is a process that can be used to reduce thepopulation of pathogens on sprouts.