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United States Department of Agriculture

Agricultural Research Service

Title: Gamma-Radiation Decontamination of Alfalfa Seeds Naturally Contaminated with Salmonella

Authors
item Thayer, Donald
item Boyd, Glenn
item Fett, William

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2003
Publication Date: February 26, 2003
Citation: THAYER, D.W., BOYD, G., FETT, W.F. GAMMA-RADIATION DECONTAMINATION OF ALFALFA SEEDS NATURALLY CONTAMINATED WITH SALMONELLA. JOURNAL OF FOOD SCIENCE. 2003. V. 68 (5). P. 1777-1781.

Interpretive Summary: Several outbreaks of salmonellosis have been traced to the consumption of alfalfa sprouts that were grown from contaminated seeds. In this study we evaluated the ability of gamma irradiation to sanitize alfalfa seed naturally contaminated with Salmonella Mbandaka. The radiation resistance of Salmonella Mbandaka on alfalfa seed was determined to be similar to that of other salmonellae associated with outbreaks of salmonellosis due to the consumption of alfalfa sprouts. We found that the dose required to eliminate the pathogen was dependent upon the maximum concentration of the pathogen per seed not the average contamination level of the lot of seed. The results suggest that the seeds should be irradiated to a dose that will not substantially decrease the commercial yield of sprouts and be combined with other sanitation methods used by the sprouter to achieve the desired 99.999% pathogen inactivation.

Technical Abstract: The radiation resistance of Salmonella Mbandaka isolated from a naturally-contaminated lot of alfalfa seed intended for the production of food sprouts was determined to be 0.81±0.02 kGy on sterile alfalfa seed. An absorbed dose of 4 kGy, but not 3 kGy, eliminated viable Salmonella Mbandaka from samples of this lot of seed and indicated that the contamination was sporadic. Presumably uniformly inoculated seed was diluted with sterile seed and irradiated to various doses. The results indicated that the dose required to inactivate a contaminating pathogen on alfalfa seeds is dependent upon the maximum contamination per seed not the mean contamination of the lot.

Last Modified: 9/23/2014
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