Ammonia As a Decontaminant for Sprouted Seed

ResearchNote: Reduction of Escherichia coli O157:H7 and Salmonella Typhimurium inArtificially Contaminated Alfalfa Seeds and Mung Beans by Fumigation withAmmonia

Journalof Food Protection: Vol. 64, No. 11, pp. 1817-1819.


CaliforniaDepartment of Health Services, 601 North 7th Street, Sacramento, California94234-7320

SuphachaiNuanualsuwan, Hans Riemann, and Dean O. Cliver

Departmentof Population Health and Reproduction, School of Veterinary Medicine, Universityof California, Davis, California 95616, USA

Abstract-Sproutseaten raw are increasingly perceived as hazardous foods because they have beenvehicles in outbreaks of foodborne disease, often involving Escherichia coliO157:H7 and Salmonella Typhimurium. Although the source of these pathogens hasnot been established, it is known that the seeds usually are alreadycontaminated at the time sprouting begins. Earlier studies had shown thatammonia was lethal to these same pathogens in manure, so it seemed reasonable todetermine whether ammonia was effective against them when associated with seedsto be used for sprouting. Experimentally contaminated (108 to 109CFU/g) and dried seeds, intended for sprouting, were sealed in glass jars inwhich 180 or 300 mg of ammonia/liter of air space was generated by action ofammonium sulfate and sodium hydroxide. Samples were taken after intervals up to22 h at 20°C. Destruction of approximately 2 to 3 logs was observed with bothbacteria associated with alfalfa seeds, versus 5 to 6 logs with mung beans.Greater kills are apparently associated with lower initial bacterial loads.Germination of these seeds was unaffected by the treatment. It appears that thissimple treatment could contribute significantly to the safety of sproutproduction from alfalfa seeds and mung beans.