Use of Spent Irrigation Water for Microbiological Analysis of Alfalfa Sprouts

Use of Spent Irrigation Water forMicrobiological Analysis of Alfalfa Sprouts
Journal of Food Protection: June 2001, Vol. 64, No. 6, pp.802-806.
T. Fu, D. Stewart, J Schlesser, and M. Tortorello
U.S. Food and DrugAdministration
K. Reikeke and J. Ulaszek
Illinois Instituteof Technology, National Center for Food Safety and Technology

Abstract-Numerousoutbreaks of foodborne illness have been linked to the consumption of rawsprouts. Sprout producers have been advised by the Food and Drug Administrationto include microbiological testing of spent irrigation water during productionas part of an overall strategy to enhance the safety of sprouts. Alfalfa sproutsand irrigation water were analyzed to show the feasibility of using irrigationwater for monitoring the microbiological safety of sprouts. Sprouts and waterwere produced and harvested from both commercial-scale (rotary drum) andconsumer-scale (glass jars) equipment. Rapid increases of aerobic mesophilesoccurred during the first 24 h of sprouting, with maximum levels achieved after48 to 72 h. The counts in irrigation water were on average within approximately1 log of their respective counts in the sprouts. Similar results were obtainedfor analysis of Escherichia coli O157:H7 in irrigation water and sprouts grownfrom artificially inoculated seeds. Testing of spent irrigation water indicatedthe contamination status of alfalfa sprouts grown from seeds associated withoutbreaks of Salmonella infection.