Reduction of Ecoli Salmonella On Mung Bean Seed by Chlorine Treatment

Research Note: Reduction of EscherichiaColi O157:H7 and Salmonella spp. on Laboratory-Inoculated Mung Bean Seed byChlorine Treatment

Journal of Food Protection: Vol. 65, No. 5, pp. 848­852.
William F. Fett
Eastern Regional Research Center, Agricultural Research Service, U.S.D.A

Abstract contaminated raw mung bean sprouts occurred in the past 2 years andwere caused by Salmonella Enteritidis. The original source of the pathogens isthought to have been the seed. The aim of this study was to determine whethertreatment with aqueous chlorine would eliminate the pathogens from mung beanseed inoculated in the laboratory with four-strain cocktails of Escherichia coliO157:H7 and Salmonella spp. Treatments (for 5, 10, or 15 min) with buffered (500mM potassium phosphate, pH 6.8) or unbuffered solutions containing 0.3 or 3.0%(wt/vol) Ca(OCl)2 were tested. In order to mimic common commercial practice,seed was rinsed before and after treatment with sterile tap water. Treatment for15 min with buffer (500 mM potassium phosphate, pH 6.8) or sterile water incombination with the seed rinses resulted in maximum reductions of approximately3 log10 CFU/g. The largest reductions (4 to 5 log10 CFU/g) for the chlorinetreatments in combination with the rinses were obtained after treatment withbuffered 3.0% (wt/vol) Ca(OCl)2 for 15 min. Treatment of mung bean seed for 15min with unbuffered or buffered 3.0% (wt/vol) Ca(OCl)2 did not adversely affectgermination. Even though treatments with 3% (wt/vol) Ca(OCl)2 in combinationwith the water rinses were effective in greatly reducing the populations of bothbacterial pathogens, these treatments did not result in the elimination of thepathogens from laboratory-inoculated seed.