ARS | Publication request: CHEMICAL, PHYSICAL AND BIOLOGICAL METHODS FOR CONTROLLING HUMAN PATHOGENS ON SPROUTS

Submitted to: United States Japan Natural Resources Protein Panel
Publication Type: Proceedings
Publication Acceptance Date: November 1, 1999
Publication Date: November 7, 1999
Citation: Fett, W.F., Rajkowski, K.T., Thayer, D.W. 1999. Chemical, physical and biological methods for controlling human pathogens on sprouts. United States Japan Natural Resources Protein Panel. Proceedings, 28th Annual Meeting in Tsukuba, Ibaraki, November 7-12, p.84-89.

Technical Abstract: Sprout-related outbreaks of salmonellosis and infection with enterohemorrhagic Escherichia coli 0157:H7 are occurring with increasing frequency worldwide. In our laboratory, we are investigating new intervention strategies for sanitizing seed and for decreasing the growth of human pathogens during the sprouting process. A 10 min treatment of laboratory-inoculated alfalfa seed with buffered calcium hypochlorite (3%, w/v) resulted in four log reductions of both Salmonella and E. coli 0157:H7. In addition, Salmonella mbandaka was eliminated from naturally contaminated seed by the chlorine treatment. D-values for gamma irradiation(cesium 137 source) were 0.60 for E. coli 0157:H7 and 0.98 for Salmonella, values higher than those previously reported for these pathogens on meat. Combination treatments of irradiation followed by chlorination gave 5 log reductions of Salmonella. Addition of several different antibacterial chemicals to irrigation water did not reduce final microbial loads on alfalfa sprouts. Studies with the scanning electron microscope indicate that the ineffectiveness is most likely due to the presence of biofilms. Preliminary experiments indicate that competitive exclusion with benign plant-associated bacteria may be highly effective in controlling bacterial pathogen growth on sprouts during germination and subsequent growth.