Reduction of Escherichia coli O157:H7 and Salmonella Typhimurium in Artificially Contaminated Alfalfa Seeds and Mung Beans by Fumigation with Ammonia

Sprouts eaten raw are increasingly perceived as hazardous foods because they have been vehicles in outbreaks of food-borne disease, often involving Escherichia coli O157:H7 and Salmonella Typhimurium. Although the source of these pathogens has not been established, it is known that the seeds usually are already contaminated at the time sprouting begins. Earlier studies had shown that ammonia was lethal to these same pathogens in manure, so it seemed reasonable to determine whether ammonia was effective against them when associated with seeds to be used for sprouting. Experimentally contaminated (108 to 109 CFU/g) and dried seeds, intended for sprouting, were sealed in glass jars in which 180 or 300 mg of ammonia/liter of air space was generated by action of ammonium sulfate and sodium hydroxide. Samples were taken after intervals up to 22 h at 20°C. Destruction of approximately 2 to 3 logs was observed with both bacteria associated with alfalfa seeds, versus 5 to 6 logs with mung beans. Greater kills are ...